Electric coffee grinder: flat or conical burrs?

Conical burrs suit full-bodied, chocolatey espresso, and flat burrs suit clear, fruity cups. Fine adjustment and low retention matter just as much.Burr designs compared, measurements on fines and retention, and five grinders each for filter, espresso and by hand.

Every good electric coffee grinder breaks the beans down between two burrs. Their basic shape determines how even the grounds are, and you can taste that in the cup. But measurements also show big differences between grinders of the same design.

Flat or conical: how the two burr sets work

In a flat burr grinder, two ring-shaped discs sit parallel, one above the other. One turns, the other stays still. The beans drop into the centre, and centrifugal force drives them outwards through the gap between the discs. The narrower this gap, the finer the grounds.

In a conical burr grinder, a cone-shaped burr turns inside a fixed ring. The coffee slides downwards with gravity and gets finer and finer on the way.

The table describes tendencies from specialist articles by a Swiss roastery and a Hamburg grinder manufacturer. According to the roastery, neither design is better in principle, and the specific model matters more.

Fines and flavour: clarity versus body

Besides the set grind size, every grinder produces very fine particles under 0.1 mm, known as fines. According to the roastery, they give espresso body but raise the risk of bitterness. Grinders with few fines tend to brew clear, light espressos with floral notes.

In 2024, the Coffee Excellence Center at the Zurich university ZHAW showed how strongly fines work. When their share rose from 10 to 15 per cent, the espresso ran around 10 seconds longer. The average grind size, on the other hand, was not linked to the shot time. At espresso grind size, the talk gives typical values of 15 to 30 per cent fines for flat burrs. For conical burrs, it gives 25 to 35 per cent.

Individual grinders can differ. In 2025, the Swiss roastery measured ten single-dosing grinders between €500 and €1,000, together with the ZHAW. Of all things, the only conical grinder had the lowest share of fines. In return, its main peak, the spread of the coarser particles, was the widest.

So the share of fines alone does not explain the flavour, and the width of the distribution also counts. Even so, the test confirms the tendency. The conical grinder tasted the most full-bodied, and the flat grinder with the narrowest distribution the clearest.

Burr size, speed and heat

For home use, flat burrs range from about 54 mm to over 100 mm. According to the roastery, flat burrs grind especially evenly when the burrs are large and a strong motor keeps the torque constant. A grinder with 102 mm burrs cost around €3,000 in March 2026.

On this grinder, the speed can be adjusted from 200 to 1,700 revolutions per minute. With filter coffee, a low speed gave more clarity and less bitterness in the test, and a high speed more body.

That leaves heat. According to the Hamburg manufacturer, conical burrs run cooler. In the comparison test, the grounds were between 25.4 and 34.6°C after several shots. At 30.4°C, the conical grinder was mid-table, and a flat grinder stayed coolest. For a few servings a day, heat is therefore not a reason to buy.

Retention and single dosing: what stays in the grinder

Retention is ground coffee that stays in the grinder after grinding. The next dose pushes some of it, stale, into your cup, and the rest stays in corners. With single dosing, you weigh out each dose and grind it individually instead of storing beans in the hopper.

According to the roastery, good single-dosing grinders retain less than 0.5 g. Grinders with a bean hopper usually retain around 4 g, and in the test the range went from 1.5 to 12.2 g. The burr design does not decide this. In the comparison test, the conical grinder retained 0.2 g temporarily and 0.7 g permanently. One flat grinder showed exactly the reverse, 0.7 g temporarily and only 0.1 g permanently.

Single dosing suits you if you often change coffees or drink little. How to store the beans until then is covered in our guide How to store coffee and keep it fresh. If you grind a lot of one coffee every day, a hopper and a little retention will work fine.

Espresso or filter: adjustment and grind range

For espresso, you need very fine adjustment. According to the roastery, stepless or stepped matters less than the resolution. On weak grinders, the shot time jumps by more than 5 seconds per step. That is too coarse for a starting recipe of 25 to 30 seconds.

After every adjustment, grounds from the old setting are still in the burrs, so you grind the retained coffee out. How to set dose, yield and time is explained in How to dial in espresso: grind size and shot time.

For filter coffee, consistency matters more than fineness. According to the roastery, a grinder with a narrow main peak suits filter better. In return, filter grinders usually cannot reach espresso fineness. According to a retailer, the Fellow Ode Gen 2 with 64 mm flat burrs grinds from 250 to 1,160 µm. It is explicitly not meant for espresso.

Conversely, according to the roastery, a pure espresso grinder does not cleanly cover the coarse filter range. For both, you need a wide adjustment range. Which grind size suits the V60, Kalita and Chemex is shown in our comparison V60, Kalita Wave and Chemex compared.

The best electric grinders for filter coffee

Our ranking is based on published tests and measurements, and we have not tested the grinders ourselves. We rated grind quality, daily use and price. There is no direct comparison of all five grinders, so the places are our own assessment. There are no paid placements.

Filter coffee ranking

No. 1, Fellow Ode Gen 2. The coffee blog Coffee Chronicler, whose author is a Q Grader, calls the Ode the new king of filter grinders.

No. 2, G-Iota DF54. In the Coffee Chronicler’s blind test, it kept up with much more expensive grinders for filter, including the Ode Gen 2. The Swiss roastery, on the other hand, missed clarity and fruit with very light roasts, though in espresso.

No. 3, Option-O Lagom P64. With Mizen 64ES burrs, it impressed the roastery for espresso and filter, with only 0.2 g retention. Without a few drops of water on the beans, however, the grounds build up a lot of static.

The best electric grinders for espresso

Espresso ranking

No. 1, G-Iota DF64 Gen 2. For the Swiss roastery, it remains the first recommendation for ambitious home baristas who want lots of control with little retention.

No. 2, Niche Zero. The Niche is the only conical grinder on this list. In the roastery’s comparison test, its espresso tasted the most full-bodied, it forgave mistakes and ran the quietest. Clear, fruity shots from light roasts are easier with flat burrs.

No. 3, Eureka Mignon Specialità. In the roastery’s 2023 espresso grinder test, this hopper grinder with timer came just behind the best espresso. If you mostly drink one coffee and don’t want to weigh every dose, it suits you despite 2.7 g of retention.

The Sage Smart Grinder Pro is left out on purpose, as according to the roastery, inexpensive single-dosing grinders have now overtaken it.

You can also spend less. In 2019, Stiftung Warentest, Germany’s consumer testing organisation, found good burr grinders from around €45, with up to 3.9 g of residue. Blade grinders only chop the beans and, according to the roastery, are not an option if flavour matters to you. How light and dark roasts differ in the cup is explained in Light, medium or dark roast: flavour, acidity and caffeine compared.

The best hand grinders

A hand grinder needs no electricity and, according to the roastery, retains hardly any coffee. It suits filter coffee, travel and a small budget. For espresso, you need fine adjustment. Here too, the places are based on published tests, not our own.

Hand grinder ranking

No. 1, 1Zpresso K-Ultra. The Coffee Chronicler calls it the strongest all-round hand grinder on the market. Thanks to its external adjustment, you can switch between filter and espresso without taking it apart. We could not find his value tip, the Mavo Phantox Pro, at any German retailer.

No. 2, Comandante C40 MK4. For the roastery, it is the benchmark among hand grinders. The Coffee Chronicler praises it for filter and espresso but sees cheaper grinders as almost level. The Red Clix extra axle halves the steps to 15 µm.

No. 3, 1Zpresso J-Ultra. According to the Coffee Chronicler, its shots taste similar to those from much more expensive electric grinders. For filter, the K-Ultra or ZP6 Special are a better fit.

Full-bodied espresso from dark roasts points to conical burrs, while clear, light coffees and filter point to flat burrs. Within each design, measurements of fines and retention decide.

Last updated: 24 October 2026.