How to Clean a Coffee Grinder (Blade and Burr)

Short answer: Unplug the grinder. For a blade grinder, grind a tablespoon of uncooked white rice to powder, dump it, and wipe the chamber with a dry cloth. For a burr grinder, take off the hopper, remove the top burr, brush the grounds out of the burrs and chamber with a stiff brush, and wipe the rest with a dry cloth; or run grinder cleaning tablets through it. Never put water on the burrs or blade chamber. Do this monthly, and more often if you grind dark, oily beans.

Why it matters

Coffee beans are oily. Every time you grind, a film of oil and fine coffee dust is left on the blades or burrs and the walls of the chamber. Within a couple of weeks that oil goes rancid, and from then on every fresh bean you grind picks up a stale, bitter edge on its way through. People often blame the coffee or the brewer when the grinder is the problem.

Built-up grounds also clog burr grinders, which makes the grind uneven and the motor work harder.

What you need

• A stiff brush. A clean, dry paintbrush or a toothbrush works; grinder brushes are cheap.
• A dry cloth or paper towels.
• For blade grinders: a tablespoon of uncooked white rice.
• For burr grinders: grinder cleaning tablets (optional but easy).
• A wooden skewer or toothpick for stuck grounds.

Cleaning a blade grinder

1. Unplug it.
2. Tip out loose grounds and wipe the chamber with a dry cloth.
3. Grind a tablespoon of uncooked white rice for 20 to 30 seconds until it is a fine powder. The rice scrubs oil off the blade and walls and absorbs it.
4. Dump the rice powder and wipe the chamber again. It will come out looking much cleaner than the first wipe.
5. Grind a teaspoon of coffee and throw it away, to clear any rice dust.

Some makers advise against rice because very hard grains can dull the blade; brown rice is harder than white, so stick to white. If you would rather not, grinder tablets do the same job.

Cleaning a burr grinder

Burr grinders need more care, because the burrs are precision parts and the motor sits right under them.

1. Unplug it and grind any beans out of the hopper, or tip them back into their bag.
2. Remove the hopper and the grounds bin. If the manual says these are washable, wash them in warm soapy water and dry fully. Many hoppers are plastic that clouds in the dishwasher; hand wash.
3. Remove the top burr. On most home grinders it lifts or twists out once the hopper is off; the manual shows how. Note the grind setting first so you can put it back.
4. Brush the burrs, both the one in your hand and the one still in the machine, working the brush along the grooves. A skewer gets stuck grounds out of the corners.
5. Brush the chamber and the chute where the grounds come out. This chute is where most old coffee hides.
6. Vacuum the chamber if you have a hose attachment; it pulls out dust the brush misses.
7. Wipe with a dry cloth, reassemble, and set the grind back to where it was.
8. Grind and discard a small handful of beans to clear anything left.

Grinder cleaning tablets

These are the shortcut. Run a dose of tablets through the grinder like beans, then grind and discard a handful of coffee. They absorb oil and push out old grounds without opening anything. Use them monthly between brush-outs, or whenever the grinder smells stale. They are the only “run it through” method the burr grinder makers generally approve of.

What not to do

• No water on the burrs or in the blade chamber. Burrs rust; motors die. The only washable parts are the ones the manual names.
• No rice in a burr grinder unless the maker says it is fine. Most say it is not.
• No pressing the burrs back together with force. If the top burr does not seat, something is in the way; brush it out.
• No running the grinder empty for long. Burrs spinning against each other with nothing between them wear.

Hand grinders

Hand burr grinders come apart fully: unscrew the handle and adjustment nut, lift the burr out, brush everything, and reassemble. Count the clicks on the adjustment nut before you take it apart so you can return to your setting. Same rules: brush, no water on the burrs.

How often

A clean grinder is also an even grinder. If your coffee has drifted bitter or sour without you changing anything, clean the grinder before you change the beans; our grind size chart covers what to do if the grind itself is the problem.

FAQ

How often should I clean my coffee grinder?

A quick brush-out weekly, a proper clean monthly for daily use. If you switch between dark oily beans and light ones, or you notice a stale or rancid smell when you open it, clean it now.

Can I wash a coffee grinder with water?

Only the removable parts that the manual says are washable, usually the hopper and grounds bin. Never the burrs or blade chamber: water causes rust on the burrs and gets into the motor. Dry-clean those with a brush.

Does grinding rice clean a grinder?

For a blade grinder, yes: a tablespoon of uncooked white rice ground to powder scrubs oil off the blade and chamber. Most burr grinder makers advise against rice, because hard grains can strain the motor and burrs. Use grinder cleaning tablets or a brush for burrs.

What are grinder cleaning tablets?

Small pellets of food-safe, starch-based material that you run through the grinder like beans. They absorb oils and push out old grounds. They work in any grinder and are the easiest deep clean for a burr grinder you do not want to take apart.

My grinder smells rancid. Is it ruined?

No. Rancid coffee oil is the usual cause and it cleans off. Brush out the burrs and chamber, run cleaning tablets or (blade grinder only) rice, wipe with a dry cloth, and grind a small batch of beans you do not mind wasting to clear the last of it.