Espresso Grind Size: Why There Is No Universal Number, and What a Coarser Grind Can Do

Search for espresso grind settings and you'll find numbers: “12 clicks,” “setting 8.” They're someone's answer on someone's grinder with someone's coffee. What you can take from them is less than it looks, and the useful version of this topic is what the setting does and how to read it.

How fine, really?

Breville's starting point is grounds with a texture similar to fine table salt. A pinch between your fingers is good enough to get into the right area on a new grinder. Coffee for espresso needs to be that fine because the water is in contact with it for less than a minute, as Breville's extraction guide notes.

After that, feel stops being much use. The shot takes over: same dose, same yield, and the time and taste tell you where you are. Breville aims for 25 to 30 seconds and says a good cup can take anywhere from 20 to 40. How to dial in espresso is the routine for that.

Why no number travels

Look at how differently grinders count:

Even two espresso grinders from the same maker don't share a scale. So “setting 10” is only a description of where one dial sits on one machine. The burr-gap figure from 1Zpresso is the kind of number that could travel, but few makers publish one, and a gap isn't a particle size.

The number moves with the bag

Breville says the darker the roast, the finer the setting should be, and asks you to consider a coffee's origin, roast and age. A Cell Press release on a 2023 study in Matter adds that dark roasts came out much finer than light roasts at the same setting. Those two points don't cancel out so much as show how little a setting number tells you. Write your setting down per coffee, and expect to move it.

See how to dial in a new bag

Where finer stops working

“Finer means more extraction” is the standard logic, and Cameron and colleagues (Matter, 2020) tested it. Their model assumed water flows evenly and predicted extraction would keep rising as the grind got finer. Their measurements showed a peak instead: extraction fell at very coarse settings and also at very fine ones. They attributed the fall at fine settings to uneven flow, and linked it to poor repeatability from shot to shot.

The University of Portsmouth's release gives the mechanism in simple terms. Very fine particles can clog parts of the bed, water can't reach them, and that coffee goes to waste. We read the abstract and the press releases, not the full paper, so we stay with what those say.

In the cup, the practical rule stays simple. Sour means finer as a first step. First step, yes. If you are already very fine and it stays sour, go coarser. Sour espresso goes through this in order.

What a coarser grind can do

Here is the part that surprises people. The Portsmouth release says that fewer beans, ground more coarsely, gave a drink that was just as strong and more consistent from cup to cup, and cheaper to make. The authors were looking at the reasons shots vary, and using less coffee turned out to be a side benefit. They don't claim to have found the best-tasting recipe, and flavor preference stays yours.

Note what comes with it: a coarser grind at a lower dose runs faster, often outside the 25 to 30 seconds printed in most guides, Breville's included. So this is a different recipe and not a repair for a bad shot. Worth a try if you want to experiment:

1. Start from a recipe you like

   Keep a note of its dose, yield, time and setting, so you can go back.

2. Take a gram or two off the dose

   Keep the yield the same, so the ratio gets longer on purpose.

3. Go a few steps coarser

   Pull the shot and let it run to the same yield, even if it finishes sooner than you are used to.

4. Taste them side by side

   Then pull the same recipe a few times. The claim to check is consistency, as much as flavor.

Static, clumps and the fine end

Fine grinding also comes with static. Méndez Harper and Hendon (Matter, 2023) found that grinding builds up charge that makes particles clump and cling, that darker roasts charged more than lighter ones, and that coarser settings produced less. A small amount of water added just before grinding reduced clumping and made espresso shots more consistent, according to the Cell Press release. Check your grinder's manual before you add water to anything that goes through it, since the release gives no guidance on that.

Clumps you can see are a job for preparation, and a WDT tool or better puck prep comes before any grinder change.

Does the burr shape change the answer?

Less than the marketing suggests. Baratza, which sells both, describes conical burrs as round and sweet, slightly more forgiving, and lower in retention, and flat burrs as clean and articulate. On steel against ceramic, it says no burr is better and each just emphasizes different qualities. That's a maker's framing, and we found no neutral study we could read. Our grinder comparison sets burrs, steps and retention side by side.

When the grinder is the limit

What you need from a grinder is steps small enough to land between too fast and too slow. If one click jumps across that gap, the setting you want doesn't exist on your grinder. No amount of tamping fixes that, so a new grinder is the honest answer, and our espresso grinder guide is the place to choose one. It's part of the same decision as your semi-automatic machine. For the bag itself, read espresso beans vs coffee beans.