Flat or conical burrs — which is better?

Neither wins outright, and anyone claiming otherwise is describing a preference.

What actually differs

Flat burrs are two parallel rings that grind coffee between their faces. They tend to produce a narrower particle distribution — more particles close to the target size, fewer outliers.

Conical burrs are a cone inside a ring, with coffee falling through the gap. They typically produce a slightly wider distribution with a characteristic secondary population of fines.

What that does in the cup

Narrower distribution reads as clarity: individual flavours separate, so a washed Ethiopian tastes floral and citric rather than generically pleasant. That suits light roasts and single origins, and it suits filter brewing where there is nothing else in the cup to hide behind.

Wider distribution reads as body: a rounder, heavier, more blended cup with a more forgiving margin for error. That suits dark roasts, espresso in milk, and anyone who does not want to chase a dial.

Practical considerations that matter more

Burr size affects speed and heat more than geometry does — a 64 mm flat and a 48 mm conical grind at very different rates.

Alignment matters enormously on flat burrs and is more forgiving on conicals. A misaligned flat burr set performs worse than a well-made conical one.

Retention tends to be lower on conicals, because gravity helps clear them.

How to choose

If you drink light single origins as filter, flat. If you drink dark roast espresso with milk, conical, and you will not hear the difference anyway. At the price points most people shop at, the specific grinder matters far more than the geometry — a good conical beats a mediocre flat comfortably.