Conical vs flat burr grinders

How conical and flat burrs work

A conical burr set has a cone-shaped inner burr that turns inside a ring-shaped outer burr. Beans fall into the top, are cracked by the coarse teeth and then ground finer as they move down the narrowing gap. Gravity helps feed coffee through, so conical grinders can run at lower speeds and are often quieter.

A flat burr set has two flat rings facing each other. Beans enter the centre and are thrown outwards by the spinning burr, passing between the cutting faces to the edge. The particles exit through a chute. Flat burrs need accurate alignment to grind evenly, and they can hold a little more coffee inside unless the design reduces retention.

Burr sizes in common grinders

Larger burrs grind faster and usually more evenly at the same speed, though design matters too. The table below uses burr facts from the makers' listings where they are stated.

What each means in the cup

Conical grinders are often described as giving espresso more body and a rounder, chocolatey character, because they produce a few more very fine particles alongside the main grind. This suits medium and darker roasts and classic milk drinks.

Flat burr grinders are often described as giving more clarity and separation of flavours, especially with light roasts and filter coffee. Grind distribution is narrower, so shots can taste brighter and cleaner. These are tendencies rather than rules: a well-made conical grinder will outperform a poorly aligned flat one.

Retention, noise and workflow

Retention is the coffee left inside the grinder after each dose. Low retention matters if you weigh single doses or switch beans often. Single-dose flat burr grinders such as the DF64 II are designed for very low retention, with a bellows or blow-out funnel to clear the chute. Many conical grinders, including the Sette 30, use a direct path that also keeps retention low.

Conical grinders often run at lower speeds and can be a little quieter. Flat burr grinders with large burrs grind quickly but can be louder. Static and clumping vary by design; some grinders, like the DF64 II, include an ionizer to reduce static.

• Hopper-fed daily espresso with one bean: a conical grinder is simple and forgiving.
• Single dosing and switching beans: a low-retention single-dose grinder of either type.
• Light roasts and filter: flat burrs are a popular choice.

Choosing a grinder

Start with your brew method. Espresso needs fine, precise adjustment; filter needs consistency at medium to coarse settings. Then look at adjustment steps, retention and size. Our espresso grinder guide and filter grinder guide shortlist options of both burr types. Our grind size chart shows the settings each method needs.

Price and size usually rise with burr diameter, and large flat burr grinders can be heavy: the DF64 II listing gives 6.8 kg, against 2.35 kg for the Sette 30. Think about where the grinder will live and whether you will single dose or keep beans in a hopper. A hopper-fed conical grinder with timed dosing, such as the Smart Grinder Pro, is quick to use every morning. A single-dose grinder asks you to weigh beans each time but rewards you with freshness and easy bean changes.

Note:Always unplug a grinder before removing the hopper or burrs. Burr edges are sharp, so handle them carefully and use a brush, not fingers, to clear the grinding chamber.

Best grinders for espresso →

Frequently asked questions

Are flat burrs better than conical burrs? Neither is better overall. Flat burrs tend to favour clarity, conical burrs body, and build quality matters as much as shape.

Why is a good coffee grinder important? Even particles extract evenly. An uneven grind mixes over and under extracted coffee, which tastes both bitter and sour.

Do built-in grinders on espresso machines use conical burrs? Most do, including Sage's Barista range, which lists conical burr grinders.

How often should burrs be replaced? It depends on use and the burr material. Check the maker's guidance; our grinder cleaning guide covers signs of wear.