What are flat burrs? Flat vs conical burrs for home brewers

How do flat burrs grind coffee?

Flat burrs grind coffee as it travels from the center of the discs to the outside edge. Mahlkönig describes beans falling between the discs and being cut into particles as they work their way outward.

Unlike conical burrs, flat burrs cannot rely on gravity to move coffee through. Honest Coffee Guide says they use centrifugal force instead, which is why they spin faster.

Because the grind is set by two parallel faces, flat burrs are sensitive to how evenly those faces are held apart. That is where burr alignment comes in.

Do flat burrs really taste better?

Flat burrs are often said to give more clarity and less body, but whether that adds up to "better" is contested. Honest Coffee Guide says flat burrs generally produce fewer fines, which reduces body and increases clarity.

Mahlkönig, which makes flat burr grinders such as the EK43, says flat burrs give a unimodal grind and a cleaner, more defined cup. Counter Culture Coffee says flat burrs grind more uniformly and give lower astringency.

The counterpoint is in the data. Coffee ad Astra measured 24 espresso grinders and found flat burrs more uniform only on average, with "a large overlap." Honest Coffee Guide also says the unimodal rule "doesn't always fit." Some people simply prefer the body conical burrs give.

Are bigger flat burrs better?

Not necessarily, and the evidence here runs against the common assumption. Perfect Daily Grind quotes one expert saying that larger burrs generally perform better.

Coffee ad Astra did not find that in its measurements. It reports that larger flat burrs did not clearly produce more uniform or more unimodal grinds, and suggests burr geometry may matter more than burr size.

Perfect Daily Grind also notes that larger burrs need more precise alignment. A bigger burr is only an advantage if the grinder holds it accurately.

What are the downsides of flat burrs?

The usual downsides are more retention, more heat, more noise and a higher price. Honest Coffee Guide says flat burrs retain more coffee, heat up faster, cost more on average and are harder to clean.

Mahlkönig explains the retention point: grounds leave a flat burr sideways under motor force rather than falling through by gravity. Perfect Daily Grind also describes flat burr grinders as generally more expensive.

Can flat burr grinders do espresso?

Some can and some deliberately cannot, so check the specific model. Fellow says the Ode Gen 2, with 64 mm stainless steel flat burrs, is "not intended for espresso."

Other flat burr grinders are built for it. Coffee ad Astra's study of espresso grinders compared flat and conical models side by side, and single-dose grinders like the DF64 Gen 2 use flat burrs. If you want one grinder for everything, confirm the range before you buy.

Which grinders use flat burrs?

Flat burrs are common in brew-focused electric grinders and in single-dose espresso grinders. Some examples:

• Fellow Ode Gen 2. 64 mm flat burrs, 11 settings with 31 total steps, brewed coffee only. See the Ode Gen 2 settings chart.
• Mahlkönig EK43. Mahlkönig says its vertically mounted burrs retain less than traditional horizontal flat burr setups. See the EK43 settings chart.
• Wilfa Uniform and Baratza Vario+. Both are flat burr grinders in BrewMark's catalog.

To see a flat and a conical grinder from the same maker side by side, try Fellow Ode Gen 2 vs Fellow Opus. For two brew-only flat burr grinders, see Fellow Ode Gen 2 vs Wilfa Uniform. Whatever you choose, the grind converter will translate recipes written for other grinders onto your dial.