Espresso Grind Size: How to Dial In Your Grinder

Grind size is the first variable we tell people to master, and it sits at the centre of our espresso guide. Get it right and most other problems shrink. Get it wrong and nothing else you do will save the shot.

Why espresso needs a fine grind

Espresso brews in roughly 25 to 35 seconds under high pressure. That is very little time to pull flavour out of coffee, so the grounds need lots of surface area. Fine particles give the water more to work with and also slow the flow, which buys extra contact time.

Too coarse, and water rushes through. The shot is pale, thin and sour. Too fine, and the puck chokes. You get a slow drip, a dark, harsh shot and sometimes channels where water forces its way through cracks.

What “fine” actually looks like

Espresso grounds should feel a little finer than table salt and clump slightly when you pinch them. That description only gets you in the neighbourhood, though. Every grinder labels its settings differently, and the right setting changes from one bag of beans to the next.

How to dial in

Pick a fixed dose, say 18 grams, and a target yield, such as 36 grams. Keep those steady. Then:

1. Pull a shot and note how long it takes to reach your yield.
2. If it runs fast and tastes sour, grind finer.
3. If it runs slow and tastes harsh, grind coarser.
4. Move in small steps. On a stepless grinder, a tiny turn is often enough.

Holding the dose fixed matters because it lets you read the result. If you change dose and grind together, you will not know which one helped. Our piece on espresso tamping covers the other half of puck prep, since an uneven tamp can look a lot like a grind problem.

Your grinder matters more than you think

A good espresso grind needs consistency as well as fineness. Blade grinders produce a mix of dust and chunks, and the dust clogs the puck while the chunks under-extract. A decent burr grinder gives you even particles and fine enough adjustment to make the small changes espresso demands.

When to re-adjust

Beans change as they age. Freshly roasted coffee holds a lot of gas and often needs a slightly coarser grind. A few weeks later, the same beans may need you to go finer. Humidity and room temperature play a part too.

Expect to tweak your setting every few days. That is normal, not a sign you are doing it wrong. Once the grind is close, use the espresso brew ratio to fine-tune strength and body rather than chasing the grinder forever.

A quick checklist

• Fix dose and yield before touching the grind.
• Change grind in small steps.
• Purge a little coffee after big adjustments so old grounds do not skew the next shot.
• Taste every shot, even the bad ones.

Keep reading

• Espresso shot timing: what the clock can and cannot tell you
• Bitter vs sour espresso: diagnosing a shot by taste