The burrs are the cutting surfaces that grind your beans, and their geometry is the defining feature of a grinder. The two main types are conical and flat, and the debate between them is one of the oldest in coffee gear.
Both can make superb espresso. The differences are real but subtle, and they interact with alignment, burr quality and how you dial in.
Conical burrs
Conical burrs have a cone that spins inside a matching ring. They are mechanically efficient, tend to run cooler and need less motor power, which makes them common from entry level right up to high end.
Many tasters describe conical grinders as giving a rounder, heavier, more textured cup, often with a bit more body.
Flat burrs
Flat burrs grind between two parallel rings. They tend to produce a more uniform particle size, which many people associate with clarity, higher extraction and clearer separation of individual flavours.
They can demand more from the motor and are sometimes more sensitive to alignment, but a well-aligned flat-burr grinder is a favourite for lighter, more aromatic coffees.
What it means when you're buying
Choose by the cup you want and the grinder you can actually buy in your budget — burr quality and alignment often matter more than geometry alone. As a rough guide: conical for body and value, flat for clarity and high extraction. If you mostly drink milk drinks, the difference matters less than for black espresso.
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Frequently asked questions
Are flat burrs better than conical?
Neither is universally better. Flat is often linked to clarity, conical to body. Burr quality, alignment and your coffee matter at least as much as geometry.
Does burr type matter for milk drinks?
Less so — milk masks the subtle differences. For black espresso and lighter roasts the distinction is easier to taste.
Do bigger burrs grind better?
Bigger burrs grind faster and run cooler, which can help, but size alone does not guarantee a better cup. Alignment and quality are decisive.