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Grinder retention: how much old coffee stays inside (2026)

Updated 2026-10-21

Retention is the ground coffee that stays inside a grinder after you grind. Published figures for 42 grinders run from under 0.1 g to about 8 g. In all four source tests that tried a bellows, the figure fell.

What retention is

Retention is the ground coffee that stays inside a grinder after you finish. It is counted in grams.

Some sits between the burrs. Some clings to the chute, the exit and the catch cup. Chart 3 shows where.

The next time you grind, some of that old coffee can come out with your new beans.

Sources use several words for parts of the same idea: total, absolute, permanent and temporary retention. Chart 1 keeps each source's own word. The glossary has a short entry: What is retention?

Why it matters

Old grounds can mix into your next dose. That matters most when you switch beans often, because yesterday's coffee ends up in today's cup.

You also lose a little of the beans you weighed. That matters most when you weigh every dose.

Chart 2 puts a number on it for a 15 g dose.

The honest limit: it matters most when you switch beans often or weigh every dose. If you drink one coffee all week, it matters much less. The figures also come from different testers with different methods, so read gaps of a few tenths of a gram with care.

How it is measured

Testers weigh the beans they put in. They grind, then weigh the grounds that come out. What is missing stayed inside.

retention = beans in minus grounds out

Some testers also take the grinder apart to find what is stuck inside. Methods differ, and the sources show how:

Dose size differs. For the Baratza Encore ESP, CoffeeGeek used a 10 g espresso sample. For the DF64 Gen 2, Homegrounds used a 20 g dose, with bellows.
Some testers split the total. For the Mahlkönig X64 SD, Kaffeemacher reports 0.9 g in total, 0.3 g permanent and 0.6 g temporary.
Sources can disagree. For the Varia VS4 Precision, Whole Latte Love reports 0.71 g (without bellows or spray) and Kaffeemacher reports about 2 g.
This page prints each source's own number, in grams, beside its condition. Nothing is converted or averaged.

Retention, grinder by grinder

Chart 1

Retention per grinder, in grams

All 8 hand grinders stay at 0.2 g or less. 18 of 34 electric grinders keep 1 g or more.

Hand grinder
Electric grinder
Figure
With an aid
Range
Other figure

Sorted from the lowest to the highest headline figure. Each figure is the source's own and links to it. The Mahlkönig E64 WS Home is off the scale at 4.1 g, marked with a break. The Mahlkönig X54 Allround Home is off the scale at 4.1 g, marked with a break. The Graef CM 800 is off the scale at about 8 g, marked with a break.

Data table: every figure, its condition and its source

Grinder	Type	Figure	Role	Condition	Source	What the source says
Timemore Sculptor 078S	Electric	under 0.1 g	Headline, with an aid	with the rotary knocker	Barista Magazine 2025-06-13; FLTR Magazine 2025-09-17	Tests show retention usually below 0.1 g with the rotary knocker, and a reviewer says what goes in comes out.
Turin DF83V	Electric	0 to 0.1 g	Headline, with an aid	with bellows	The Coffee Chronicler 2024-05-03; Tom's Grinder Lab; Coffeeble 2026-02-26	Reviewers report very low retention, and tests show 0.0 to 0.1 g with the bellows.
1Zpresso J-Ultra	Hand	about 0.1 g	Headline		RoastAroma	RoastAroma lists retention at about 0.1 g.
1Zpresso ZP6 Special	Hand	about 0.1 g	Headline		RoastAroma	RoastAroma lists retention at about 0.1 g, a 90-click range at 22 microns, and a finest setting near 240 microns.
Kingrinder K6	Hand	0.1 g	Headline, with an aid	at 40 clicks, after a water mist and three taps	9 Bar Benchmark 2026-03-30	9 Bar Benchmark found 0.1 g retained at 40 clicks after a mist and three taps.
Timemore C3 ESP Pro	Hand	0.1 g	Headline, with an aid	at setting 0.8.0, using a water mist and three taps	9 Bar Benchmark 2026-03-31	9 Bar Benchmark found 0.1 g retained at setting 0.8.0 using a water mist and three taps.
Timemore Whirly 01S	Electric	about 0.1 g	Headline		Quaffee 2025-06-25; CoffeeGeek 2026-01-25	Tests put retention at about 0.1 g.
Timemore Bricks 01S	Electric	0.05 to 0.2 g	Headline	about 0.05 g retention in one test and 0.1 to 0.2 g in another	Quaffee 2025-07-01; La Milan Cafe 2025-07-30	Tests show about 0.05 g retention in one test and 0.1 to 0.2 g in another.
Timemore Chestnut C5 ESP Pro	Hand	0.1 to 0.2 g	Headline		Espresso Rabbit Hole 2026-09-22	Espresso Rabbit Hole reports retention usually 0.1 to 0.2 g and about a minute for 18 g.
Timemore Sculptor 064S	Electric	0.1 to 0.2 g	Headline		Nucleus Coffee 2024-05-21	Nucleus reports 150 W motor and retention around 0.1 to 0.2 g.
1Zpresso K-Ultra	Hand	about 0.2 g	Headline		RoastAroma	RoastAroma lists retention at about 0.2 g.
1Zpresso Q2	Hand	about 0.2 g	Headline	while the burrs were new	Home Coffee Expert 2026-06-11	Home Coffee Expert says it lost around 0.2 g of grounds each time while the burrs were new.
Fellow Opus 2	Electric	about 0.2 g	Headline		The Coffee Chronicler 2026-09-29	Tests show retention around 0.2 g, falling to about 0.1 g when the lid is pumped like a bellows.
Fellow Opus 2	Electric	about 0.1 g	With an aid	lid pumped like a bellows	The Coffee Chronicler 2026-09-29	Tests show retention around 0.2 g, falling to about 0.1 g when the lid is pumped like a bellows.
Kingrinder K4	Hand	about 0.2 g	Headline		RoastAroma	RoastAroma lists retention at about 0.2 g.
Baratza Encore ESP Pro	Electric	0.1 to 0.3 g	Headline		Espresso Rabbit Hole 2026-02-04	Retention is usually 0.1 to 0.3 g in tests, against up to 1 g on the Encore ESP.
DF54	Electric	0.2 to 0.3 g	Headline	without bellows	The Coffee Chronicler 2024-04-08	Coffee Chronicler measured 0.2 to 0.3 g retention without the bellows and 0.0 to 0.1 g with them, and 14 g of espresso grounds in 24 s.
DF54	Electric	0 to 0.1 g	With an aid	with bellows	The Coffee Chronicler 2024-04-08	Coffee Chronicler measured 0.2 to 0.3 g retention without the bellows and 0.0 to 0.1 g with them, and 14 g of espresso grounds in 24 s.
DF54	Electric	0.1 to 0.3 g	Other figure		The Coffee Chronicler 2024-04-08; Nucleus Coffee 2024-05-03	Tests show very low retention, usually 0.1 to 0.3 g.
DF64 Gen 2	Electric	about 0.3 g	Headline, with an aid	20 g dose, with bellows	Homegrounds 2025-02-28	Homegrounds measured over 90 dB and about 0.3 g retention on a 20 g dose with bellows.
Rommelsbacher EKM 600	Electric	about 0.5 g	Headline	at the finest setting, without bellows, maker's figure	Rommelsbacher	Rommelsbacher cites 0.355 mm for the fine particle range and about 0.5 g retention at the finest setting without the bellows. TestMagazine gives the same figures without naming a method, and neither magazine reports a pulled shot.
Baratza Sette 270	Electric	under 1 g	Headline		The Coffee Folk 2026-02-05	Consistent, fluffy fine grounds, with under 1 g retention and 3.5 to 5.5 g per second in tests.
Niche Zero	Electric	0.4 to 0.7 g	Headline	total retention	Coffee Blog UK 2026-01-05	Coffee Blog UK cites Dave Corbey testing 0.4 to 0.7 g total retention and 0.3 g maximum exchanged retention.
Niche Zero	Electric	0.3 g	Other figure	exchanged retention	Coffee Blog UK 2026-01-05	Coffee Blog UK cites Dave Corbey testing 0.4 to 0.7 g total retention and 0.3 g maximum exchanged retention.
Fellow Opus	Electric	0.5 to 0.8 g	Headline		LifeStyle Lab 2023-09-06	LifeStyle Lab puts retention at about 0.5 to 0.8 g.
Eureka Oro Mignon Single Dose Pro	Electric	about 0.7 g	Headline	temporary retention	Kaffeemacher 2025-05-10; The Coffee Chronicler 2025-04-04	Tests show about 0.7 g temporary retention, with espresso doses coming up 0.7 to 1.2 g short.
Eureka Oro Mignon Single Dose Pro	Electric	0.2 g	Other figure	permanent retention	Kaffeemacher 2025-05-10	Kaffeemacher timed 18 g in about 11 seconds and measured 0.2 g permanent retention, down from 0.3 to 0.4 g on the old model.
Varia VS4 Precision	Electric	0.71 g	Headline	without bellows or spray	Whole Latte Love 2026-01-13	Whole Latte Love measured retention under 0.1 g with a water spray and 0.71 g without bellows or spray, and quotes Varia's own figure of at most 0.06 g with a spray.
Varia VS4 Precision	Electric	under 0.1 g	With an aid	with a water spray	Whole Latte Love 2026-01-13	Whole Latte Love measured retention under 0.1 g with a water spray and 0.71 g without bellows or spray, and quotes Varia's own figure of at most 0.06 g with a spray.
Varia VS4 Precision	Electric	about 2 g	Other figure	total retention	Kaffeemacher 2026-06-20	Tests show about 2 g of retention in total, which a reviewer calls poor for a single-doser.
Mahlkönig X64 SD	Electric	0.9 g	Headline	total retention	Kaffeemacher 2025-06-13	Tests show 0.9 g total retention, 0.3 g permanent and 0.6 g temporary, rather high for a single doser.
Mahlkönig X64 SD	Electric	0.6 g	Other figure	temporary retention	Kaffeemacher 2025-06-13	Tests show 0.9 g total retention, 0.3 g permanent and 0.6 g temporary, rather high for a single doser.
Mahlkönig X64 SD	Electric	0.3 g	Other figure	permanent retention	Kaffeemacher 2025-06-13	Tests show 0.9 g total retention, 0.3 g permanent and 0.6 g temporary, rather high for a single doser.
Varia VS3 Gen 2	Electric	1.1 g	Headline	without bellows	Kaffeemacher 2024-01-27	Tests show 1.1 g retention without the bellows and 0.05 g with them.
Varia VS3 Gen 2	Electric	0.05 g	With an aid	with bellows	Kaffeemacher 2024-01-27	Tests show 1.1 g retention without the bellows and 0.05 g with them.
De'Longhi Dedica KG521	Electric	1.4 g	Headline		Kaffeemacher 2022-01-16	Kaffeemacher measured 86.2 dB, 1.4 g of retention and 17.1 g per 10 seconds.
Baratza Virtuoso+	Electric	about 1.5 g	Headline		Coffee Review 2020-06-13	Coffee Review lists a 40 mm conical burr at 550 RPM and about 1.5 g retention.
Baratza Encore	Electric	1 to 2 g	Headline		Brewww	Brewww puts retention at about 1 to 2 g.
Wilfa Svart Uniform	Electric	1 to 2 g	Headline	North American model	CoffeeGeek 2023-02-08	CoffeeGeek measured 78.5 dB with the lid on, about 0.8 g per second, and 1 to 2 g of retention that a lid flap clears. Its test unit was the North American model.
Niche Duo	Electric	1.6 g	Headline	absolute retention	Kaffeemacher 2023-12-09	Kaffeemacher measured 77.6 dB, 1.6 g absolute retention, 0.16 g single-dose retention and 0.16 g dose standard deviation.
Niche Duo	Electric	0.16 g	Other figure	single-dose retention	Kaffeemacher 2023-12-09	Kaffeemacher measured 77.6 dB, 1.6 g absolute retention, 0.16 g single-dose retention and 0.16 g dose standard deviation.
Eureka Mignon Zero 65	Electric	1.8 g	Headline	absolute retention	Kaffeemacher 2025-08-09	Kaffeemacher measured 79.2 dB, 17 s for 18 g, 1.8 g absolute retention and 34.5 C grounds temperature for the 65 AP.
Eureka Mignon Zero 65	Electric	about 0.55 g	Other figure	total retention, maker's figure	Eureka	Eureka claims about 0.55 g total retention for the All Purpose version.
Baratza Encore ESP	Electric	about 2 g	Headline	10 g espresso sample	CoffeeGeek 2023-10-20	CoffeeGeek measured retention of typically about 2 g on a 10 g espresso sample. With the single-dose hopper it got 20 g out for 20 g in.
Baratza Encore ESP	Electric	1.1 g	Other figure		Coffee Chronicler 2024-07-26	Coffee Chronicler measured retention of 1.1 g.
Varia VS6	Electric	2.3 g	Headline	absolute retention	Kaffeemacher 2025-10-11	Kaffeemacher measured 2.3 g absolute retention, of which 0.35 g is temporary and 2.0 g permanent, without using the blower.
Varia VS6	Electric	up to 0.1 g	With an aid	with a water spray	CoffeeSnobs forum 2024-12-13; CoffeeSnobs forum 2025-06-09	One early owner puts retention at 0.5 to 0.7 g shot to shot without the bellows. A later owner says retention is at most 0.1 g with a water spray.
Varia VS6	Electric	0.5 to 0.7 g	Other figure	without bellows	CoffeeSnobs forum 2024-12-13; CoffeeSnobs forum 2025-06-09	One early owner puts retention at 0.5 to 0.7 g shot to shot without the bellows. A later owner says retention is at most 0.1 g with a water spray.
Varia VS6	Electric	0.35 g	Other figure	temporary retention	Kaffeemacher 2025-10-11	Kaffeemacher measured 2.3 g absolute retention, of which 0.35 g is temporary and 2.0 g permanent, without using the blower.
Varia VS6	Electric	2 g	Other figure	permanent retention	Kaffeemacher 2025-10-11	Kaffeemacher measured 2.3 g absolute retention, of which 0.35 g is temporary and 2.0 g permanent, without using the blower.
Eureka Mignon Libra	Electric	2.4 g	Headline	total retention	Kaffeemacher 2022-12-17	Kaffeemacher measured 79.8 dB, 20.2 g in 10 seconds, 2.4 g total retention and 36.1 °C average grinding temperature, in an older test.
Sage Dose Control Pro	Electric	2 to 3 g	Headline	about 2 g in current tests and up to 3 g in earlier ones	CoffeeGeek 2023-08-04	CoffeeGeek measured retention of about 2 g in current tests and up to 3 g in earlier ones.
Eureka Mignon Specialità	Electric	2.7 g	Headline	absolute retention	Kaffeemacher 2022-03-12	Kaffeemacher measured 78.9 dB, 2.7 g absolute retention, 21.3 g in 10 s and a 0.11 g dose standard deviation.
Eureka Mignon Specialità	Electric	about 1 g	Other figure	exchanged retention	Kaffeemacher 2022-03-12; The Coffee Chronicler 2021-10-02	Reviewers describe low retention, with about 1 g exchanged in one reviewer's use.
Eureka Mignon Zero 55S	Electric	2.7 g	Headline	absolute retention	Kaffeemacher 2025-08-09	Kaffeemacher measured 83.1 dB, 10.5 s for 18 g, 2.7 g absolute retention and a grinding temperature of 28.9 °C.
Eureka Mignon Zero 55S	Electric	1.6 g	Other figure	permanent retention	Kaffeemacher 2025-08-09	Tests show 2.7 g absolute retention, of which 1.6 g is permanent, so it is not a zero-retention grinder.
Sage Smart Grinder Pro	Electric	about 2.7 g	Headline	found by taking the grinder apart	Kaffeemacher 2020-04-14	Kaffeemacher measured 16 seconds for 18 g and about 2.7 g of retention, found by taking the grinder apart.
Eureka Mignon Manuale 15BL	Electric	about 3.2 g	Headline	total retention	Kaffeemacher 2026-01-05	Stock retention is about 3.2 g in total in tests, falling to 0.1 to 0.2 g only with a bellows hopper.
Eureka Mignon Manuale 15BL	Electric	0.1 to 0.2 g	With an aid	with a bellows hopper	Kaffeemacher 2026-01-05	Stock retention is about 3.2 g in total in tests, falling to 0.1 to 0.2 g only with a bellows hopper.
Mahlkönig E64 WS Home	Electric	4.1 g	Headline	total retention	Kaffeemacher 2026-03-21	Tests show 4.1 g total retention, 3.8 g temporary and 0.3 g permanent, noticeable for home use.
Mahlkönig E64 WS Home	Electric	3.8 g	Other figure	temporary retention	Kaffeemacher 2026-03-21	Tests show 4.1 g total retention, 3.8 g temporary and 0.3 g permanent, noticeable for home use.
Mahlkönig E64 WS Home	Electric	0.3 g	Other figure	permanent retention	Kaffeemacher 2026-03-21	Tests show 4.1 g total retention, 3.8 g temporary and 0.3 g permanent, noticeable for home use.
Mahlkönig X54 Allround Home	Electric	4.1 g	Headline		Kaffeemacher 2022-03-02	Kaffeemacher measured 4.1 g retention at an espresso setting after the revised flapper, against 7.6 g on an early unit.
Graef CM 800	Electric	about 8 g	Headline		Kaffeemacher 2022-10-06	Kaffeemacher measured about 8 g retention and reported dissolved solids of about 17.9 percent, against up to 21.5 percent for the other grinders in its test.

What it means for a 15 g dose

Chart 2 Computed

Share of a 15 g dose that equals the retained coffee

For 23 of 42 grinders the figure is under 5% of a 15 g dose. For 16 it is 10% or more.

Hand grinder
Electric grinder
No aid
With an aid
Range

Computed here from Chart 1: the headline figure divided by 15 g. The sources did not report these shares. A bar shows the share if all of the retained coffee came out with the next dose. A lighter bar is a range.

Data table: the computed shares

Grinder	Headline figure (grams)	Share of a 15 g dose (computed)
Timemore Sculptor 078S	under 0.1 g	under 0.7%
Turin DF83V	0 to 0.1 g	0% to 0.7%
1Zpresso J-Ultra	about 0.1 g	0.7%
1Zpresso ZP6 Special	about 0.1 g	0.7%
Kingrinder K6	0.1 g	0.7%
Timemore C3 ESP Pro	0.1 g	0.7%
Timemore Whirly 01S	about 0.1 g	0.7%
Timemore Bricks 01S	0.05 to 0.2 g	0.3% to 1.3%
Timemore Chestnut C5 ESP Pro	0.1 to 0.2 g	0.7% to 1.3%
Timemore Sculptor 064S	0.1 to 0.2 g	0.7% to 1.3%
1Zpresso K-Ultra	about 0.2 g	1.3%
1Zpresso Q2	about 0.2 g	1.3%
Fellow Opus 2	about 0.2 g	1.3%
Kingrinder K4	about 0.2 g	1.3%
Baratza Encore ESP Pro	0.1 to 0.3 g	0.7% to 2%
DF54	0.2 to 0.3 g	1.3% to 2%
DF64 Gen 2	about 0.3 g	2%
Rommelsbacher EKM 600	about 0.5 g	3.3%
Baratza Sette 270	under 1 g	under 6.7%
Niche Zero	0.4 to 0.7 g	2.7% to 4.7%
Fellow Opus	0.5 to 0.8 g	3.3% to 5.3%
Eureka Oro Mignon Single Dose Pro	about 0.7 g	4.7%
Varia VS4 Precision	0.71 g	4.7%
Mahlkönig X64 SD	0.9 g	6%
Varia VS3 Gen 2	1.1 g	7.3%
De'Longhi Dedica KG521	1.4 g	9.3%
Baratza Virtuoso+	about 1.5 g	10%
Baratza Encore	1 to 2 g	6.7% to 13%
Wilfa Svart Uniform	1 to 2 g	6.7% to 13%
Niche Duo	1.6 g	11%
Eureka Mignon Zero 65	1.8 g	12%
Baratza Encore ESP	about 2 g	13%
Varia VS6	2.3 g	15%
Eureka Mignon Libra	2.4 g	16%
Sage Dose Control Pro	2 to 3 g	13% to 20%
Eureka Mignon Specialità	2.7 g	18%
Eureka Mignon Zero 55S	2.7 g	18%
Sage Smart Grinder Pro	about 2.7 g	18%
Eureka Mignon Manuale 15BL	about 3.2 g	21%
Mahlkönig E64 WS Home	4.1 g	27%
Mahlkönig X54 Allround Home	4.1 g	27%
Graef CM 800	about 8 g	53%

Where the coffee hides

Chart 3 Diagram, not data

Four places ground coffee stays

Ground coffee can stay in four places: around the burrs, in the chute, at the exit and catch cup, and in the hopper.

Between and around the burrs
Ground coffee can stay in the burr chamber. A bellows blows it out.

Rommelsbacher EKM 600: A reviewer says the bellows blows leftover powder out of the burrs reliably, even with beans in the hopper. lite magazin
In the chute
Grounds get stuck on the way from the burrs to the exit.

De'Longhi Dedica KG521: A reviewer says grounds get stuck in the chute. Coffee Gear Zone

Melitta Calibra: Grounds cling to the bin, chute and housing, so part of the weighed dose stays inside. Coffeeness, Sonntagmorgen
At the exit and in the catch cup
Static makes grounds cling to the bin and the cup.

De'Longhi KG89: Reviewers say static makes grounds cling to the plastic catch bin. mein-test.org, Testberichte.de

Hario Mini Slim Plus: Coffeeness says the plastic catch cup builds up static, so emptying it may need a brush. Coffeeness
In the hopper
A reviewer reports static and retention in the hopper too.

Fellow Opus: A reviewer finds it rather messy, with static and retention in the hopper and chute. Coffeeness

A schematic cross-section of an electric grinder, not to scale. The shapes show where, never how much.

Text version of the diagram

From the top: a hopper that holds the beans, a burr chamber with two burrs, an angled chute, and a spout above a catch cup.

Between and around the burrs. Ground coffee can stay in the burr chamber. A bellows blows it out.
In the chute. Grounds get stuck on the way from the burrs to the exit.
At the exit and in the catch cup. Static makes grounds cling to the bin and the cup.
In the hopper. A reviewer reports static and retention in the hopper too.

How to reduce it

Four things come up in the sources. Each card below says only what the cited reviews say.

A bellows

A bellows is a hand pump for air. It pushes air through the grinder to blow leftover grounds out.

What the sources measured

DF54: 0.2 to 0.3 g without, 0 to 0.1 g with. with bellows; The Coffee Chronicler
Eureka Mignon Manuale 15BL: about 3.2 g without, 0.1 to 0.2 g with. with a bellows hopper; Kaffeemacher
Fellow Opus 2: about 0.2 g without, about 0.1 g with. lid pumped like a bellows; The Coffee Chronicler
Varia VS3 Gen 2: 1.1 g without, 0.05 g with. with bellows; Kaffeemacher
DF64 Gen 2: about 0.3 g with the aid, no plain figure reported. 20 g dose, with bellows; Homegrounds
Turin DF83V: 0 to 0.1 g with the aid, no plain figure reported. with bellows; The Coffee Chronicler

What reviewers say

Rommelsbacher EKM 600: A reviewer says the bellows blows leftover powder out of the burrs reliably, even with beans in the hopper. lite magazin

A few drops of water (RDT)

RDT, the Ross droplet technique, is a light mist of water on the beans before you grind. Reviewers use it against static, so fewer grounds cling.

What the sources measured

Varia VS4 Precision: 0.71 g without, under 0.1 g with. with a water spray; Whole Latte Love
Varia VS6: 2.3 g without, up to 0.1 g with. with a water spray; CoffeeSnobs forum
Kingrinder K6: 0.1 g with the aid, no plain figure reported. at 40 clicks, after a water mist and three taps; 9 Bar Benchmark
Timemore C3 ESP Pro: 0.1 g with the aid, no plain figure reported. at setting 0.8.0, using a water mist and three taps; 9 Bar Benchmark

What reviewers say

Varia VS3 Gen 2: Static remains despite the anti-static treatment, and reviewers call a water spray almost essential. Kaffeemacher, The Coffee Folk
Turin DF83V: A built-in plasma generator cuts static, and reviewers say it removes the need for a water spray. Tom's Grinder Lab, Coffeeble
Timemore Sculptor 078S: FLTR says beans sprayed with water sometimes stick to the smooth coating in the hopper, and a tap clears them. FLTR Magazine
Baratza Encore ESP Pro: CoffeeGeek reports minimal static from the built-in plasma coil, and warns that spritzing beans with water can gum it up. CoffeeGeek

Purging

A purge means grinding a few beans and throwing them away, so the old coffee goes out first.

What reviewers say

Sage Smart Grinder Pro: Coffee Kev suggests a short purge each morning. Kaffeemacher advises grinding out a few grams after 15 minutes idle. Kaffeemacher, Coffee Blog
Sage Smart Grinder Pro: Coffeeness did not see chute retention problems and still suggests a 1 to 2 second purge. CoffeeGeek says never to single dose it. CoffeeGeek, Coffeeness
Rommelsbacher EKM 600: Beans left in the chute must be ground out before a new coffee goes in. TestMagazine

Tapping and knocking

A few taps on the body shake loose grounds. Some grinders have a knocker built in.

What the sources measured

Fellow Opus 2: about 0.2 g without, about 0.1 g with. lid pumped like a bellows; The Coffee Chronicler
Kingrinder K6: 0.1 g with the aid, no plain figure reported. at 40 clicks, after a water mist and three taps; 9 Bar Benchmark
Timemore C3 ESP Pro: 0.1 g with the aid, no plain figure reported. at setting 0.8.0, using a water mist and three taps; 9 Bar Benchmark
Timemore Sculptor 078S: under 0.1 g with the aid, no plain figure reported. with the rotary knocker; Barista Magazine

What reviewers say

Fellow Opus 2: Portafilter Co says some Reddit owners report 1 to 2.5 g, recovered only by tapping the body and using the lid as a bellows. Portafilter Co
Timemore Sculptor 064S: Tests show low retention, about 0.1 to 0.2 g, helped by the rotary knocker. Nucleus Coffee, The Coffee Chronicler
Timemore Sculptor 078S: Tests show retention usually below 0.1 g with the rotary knocker, and a reviewer says what goes in comes out. Barista Magazine, FLTR Magazine

Table: every figure taken with an aid

Grinder	Without the aid	With the aid	Aid	Source
DF54	0.2 to 0.3 g	0 to 0.1 g	with bellows	The Coffee Chronicler
Eureka Mignon Manuale 15BL	about 3.2 g	0.1 to 0.2 g	with a bellows hopper	Kaffeemacher
Fellow Opus 2	about 0.2 g	about 0.1 g	lid pumped like a bellows	The Coffee Chronicler
Varia VS3 Gen 2	1.1 g	0.05 g	with bellows	Kaffeemacher
Varia VS4 Precision	0.71 g	under 0.1 g	with a water spray	Whole Latte Love
Varia VS6	2.3 g	up to 0.1 g	with a water spray	CoffeeSnobs forum
DF64 Gen 2	not reported	about 0.3 g	20 g dose, with bellows	Homegrounds
Kingrinder K6	not reported	0.1 g	at 40 clicks, after a water mist and three taps	9 Bar Benchmark
Timemore C3 ESP Pro	not reported	0.1 g	at setting 0.8.0, using a water mist and three taps	9 Bar Benchmark
Timemore Sculptor 078S	not reported	under 0.1 g	with the rotary knocker	Barista Magazine
Turin DF83V	not reported	0 to 0.1 g	with bellows	The Coffee Chronicler

Lowest-retention picks

One pick per group: the lowest published figure taken without an aid, among the grinders with an in-stock price delivered to Lithuania. Without an aid means no bellows, water mist or knocker was used for that figure.

Hand grinder

1Zpresso J-Ultra

about 0.1 g

Lowest figure taken without an aid among in-stock hand grinders: about 0.1 g, RoastAroma.

€203.99 at Crema →

In stock, delivered to Lithuania

Electric, under €400

Timemore Whirly 01S

about 0.1 g

Lowest figure taken without an aid among in-stock electric grinders under €400 delivered: about 0.1 g, Quaffee and CoffeeGeek.

€99 at Kavos draugas / Coffee Friend →

In stock, delivered to Lithuania

Electric, any price

Timemore Bricks 01S

0.05 to 0.2 g

Next lowest figure taken without an aid among in-stock electric grinders, after the pick above: 0.05 to 0.2 g, Quaffee and La Milan Cafe.

€284.89 at Crema →

In stock, delivered to Lithuania

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Questions

What is grinder retention?

Retention is the ground coffee that stays inside the grinder after you finish, usually measured in grams. It matters because old grounds can mix into your next dose, and because you lose some of the beans you weighed. It matters most if you switch beans often or weigh every dose.

How much retention is normal?

Published figures for 42 grinders run from under 0.1 g to about 8 g, and the middle figure is 0.68 g. 17 of the 42 are at 0.3 g or less.

Do hand grinders have less retention than electric ones?

On this page, yes. All 8 hand grinders with a published figure stay at 0.2 g or less. 18 of 34 electric grinders keep 1 g or more.

Does retention matter if I single dose?

Single dosing means you weigh just the beans for one brew, grind them, and keep the rest sealed. It keeps old beans out of the grinder and makes it easy to switch coffees. It works best on grinders with low retention, because leftover grounds matter more when you grind small amounts. It matters most when you switch beans often or weigh every dose.

How can I reduce grinder retention?

Four things appear in the sources: a bellows, a few drops of water on the beans (RDT), a purge before the real dose, and a few taps. In six source tests the same grinder held less with a bellows or a water spray, for example the Fellow Opus 2, the DF54 and the Varia VS4 Precision.

How is retention measured?

Testers weigh the beans they put in and the grounds that come out. What is missing stayed inside. Methods differ in dose size and settings, so compare figures from one source with care.

Sources (54)

Every figure on this page comes from one of these. The numbers are the sources' own, digested here.

Timemore C3 ESP Pro Grinder Review, 9 Bar Benchmark, 2026-03-31 (used for Timemore C3 ESP Pro)
Kingrinder K6 Grinder Review, 9 Bar Benchmark, 2026-03-30 (used for Kingrinder K6)
Test Drive: Timemore Sculptor 078S Grinder, Barista Magazine, 2025-06-13 (used for Timemore Sculptor 078S)
Baratza Encore & Sette: Elektrische Muehlen fuer Einsteiger und Fortgeschrittene, Brewww (used for Baratza Encore)
Niche Zero Coffee Grinder Review, Coffee Blog UK, 2026-01-05 (used for Niche Zero)
Baratza Encore ESP: The Classic is Reborn, Coffee Chronicler, 2024-07-26 (used for Baratza Encore ESP)
Baratza Virtuoso+ Coffee Grinder Review, Coffee Review, 2020-06-13 (used for Baratza Virtuoso+)
Turin DF83 Review, Coffeeble, 2026-02-26 (used for Turin DF83V)
Timemore Whirly 01S vs Millab E01, CoffeeGeek, 2026-01-25 (used for Timemore Whirly 01S)
Wilfa Uniform Grinder First Look, CoffeeGeek, 2023-02-08 (used for Wilfa Svart Uniform)
Baratza Encore ESP Grinder, CoffeeGeek, 2023-10-20 (used for Baratza Encore ESP)
Breville Dose Control Pro Grinder, CoffeeGeek, 2023-08-04 (used for Sage Dose Control Pro)
New Varia VS6 (page 2), CoffeeSnobs forum, 2024-12-13 (used for Varia VS6)
New Varia VS6 (page 5), CoffeeSnobs forum, 2025-06-09 (used for Varia VS6)
Baratza Encore ESP Pro Review, Espresso Rabbit Hole, 2026-02-04 (used for Baratza Encore ESP Pro)
Timemore Chestnut C5 ESP Pro Review, Espresso Rabbit Hole, 2026-09-22 (used for Timemore Chestnut C5 ESP Pro)
Eureka Mignon Zero 65 All Purpose, Eureka (used for Eureka Mignon Zero 65)
Timemore Sculptor 078S Review, FLTR Magazine, 2025-09-17 (used for Timemore Sculptor 078S)
1Zpresso Q2 Review, Home Coffee Expert, 2026-06-11 (used for 1Zpresso Q2)
DF64 Gen 2 Grinder Review, Homegrounds, 2025-02-28 (used for DF64 Gen 2)
Test: De'Longhi KG521, A good espresso grinder to get started?, Kaffeemacher, 2022-01-16 (used for De'Longhi Dedica KG521)
Eureka Mignon Libra with integrated scale reviewed, Kaffeemacher, 2022-12-17 (used for Eureka Mignon Libra)
Eureka Mignon Manuale test, Kaffeemacher, 2026-01-05 (used for Eureka Mignon Manuale 15BL)
Eureka Mignon Specialita espresso grinder reviewed, Kaffeemacher, 2022-03-12 (used for Eureka Mignon Specialità)
Eureka Mignon Single Dose Pro reviewed, Kaffeemacher, 2025-05-10 (used for Eureka Oro Mignon Single Dose Pro)
Eureka Mignon Zero Tested: 55 S, 65 All Purpose & Classic, Kaffeemacher, 2025-08-09 (used for Eureka Mignon Zero 65, Eureka Mignon Zero 55S)
Graef CM800 Espressomuehle fuer Einsteiger im Test, Kaffeemacher, 2022-10-06 (used for Graef CM 800)
Mahlkönig E64 WS reviewed: Grind by weight with electronic grind size adjustment, Kaffeemacher, 2026-03-21 (used for Mahlkönig E64 WS Home)
Mahlkönig X54 - Home Espresso Grinder, Kaffeemacher, 2022-03-02 (used for Mahlkönig X54 Allround Home)
Mahlkönig X64 SD, Kaffeemacher, 2025-06-13 (used for Mahlkönig X64 SD)
Niche DUO espresso grinder reviewed, Kaffeemacher, 2023-12-09 (used for Niche Duo)
Sage Smart Grinder Pro, Kaffeemacher, 2020-04-14 (used for Sage Smart Grinder Pro)
The Best Single Dosing Grinder Between 500 and 1,000 Euros: The Big Comparison Test, Kaffeemacher, 2025-10-11 (used for Varia VS6)
Varia VS3 espresso grinder review, Kaffeemacher, 2024-01-27 (used for Varia VS3 Gen 2)
Varia VS4 reviewed, Kaffeemacher, 2026-06-20 (used for Varia VS4 Precision)
Timemore Bricks 01S in depth, La Milan Cafe, 2025-07-30 (used for Timemore Bricks 01S)
Fellow OPUS Review, LifeStyle Lab, 2023-09-06 (used for Fellow Opus)
DF54 Grinder Review, Nucleus Coffee, 2024-05-03 (used for DF54)
Timemore Sculptor 064S Review, Nucleus Coffee, 2024-05-21 (used for Timemore Sculptor 064S)
Portable but Capable: The Timemore Whirly 01S, Quaffee, 2025-06-25 (used for Timemore Whirly 01S)
Timemore Bricks 01s EG Review, Quaffee, 2025-07-01 (used for Timemore Bricks 01S)
1Zpresso J-Ultra Review (2026), RoastAroma (used for 1Zpresso J-Ultra)
1Zpresso K-Ultra Review (2026), RoastAroma (used for 1Zpresso K-Ultra)
1Zpresso ZP6 Special Review (2026), RoastAroma (used for 1Zpresso ZP6 Special)
Kingrinder K4 Review (2026), RoastAroma (used for Kingrinder K4)
Premium Kaffeemühle EKM 600, Rommelsbacher (used for Rommelsbacher EKM 600)
DF54 Grinder Review: When Less Is More, The Coffee Chronicler, 2024-04-08 (used for DF54)
DF83V Review, The Coffee Chronicler, 2024-05-03 (used for Turin DF83V)
Eureka Mignon Specialita Review, The Coffee Chronicler, 2021-10-02 (used for Eureka Mignon Specialità)
Eureka Single Dose Pro Review, The Coffee Chronicler, 2025-04-04 (used for Eureka Oro Mignon Single Dose Pro)
Fellow Opus 2 Review, The Coffee Chronicler, 2026-09-29 (used for Fellow Opus 2)
Baratza Sette 270 Review, The Coffee Folk, 2026-02-05 (used for Baratza Sette 270)
Turin DF83V Review, Tom's Grinder Lab (used for Turin DF83V)
Varia VS4 Review, Whole Latte Love, 2026-01-13 (used for Varia VS4 Precision)

Grinder retention: how much old coffee stays inside (2026)

What retention is

Why it matters

How it is measured

Retention, grinder by grinder

Retention per grinder, in grams

What it means for a 15 g dose

Share of a 15 g dose that equals the retained coffee

Where the coffee hides

Four places ground coffee stays

Between and around the burrs

In the chute

At the exit and in the catch cup

In the hopper

How to reduce it

A bellows

A few drops of water (RDT)

Purging

Tapping and knocking

Lowest-retention picks

1Zpresso J-Ultra

Timemore Whirly 01S

Timemore Bricks 01S

Questions