What grind size for espresso?

For espresso, the target grind sits around 200-300 µm — a fine powder that looks like table salt but denser and slightly clumpy. You dial it in precisely to pull a 25-30 s shot under 9 bars of pressure, with a typical yield of 18 g in for 36 g out (1:2 ratio), adjusting finer or coarser by a notch at a time.

Espresso asks for the finest grind of any common brewing method. The median target sits around 250 µm (0.25 mm), with a working range of 200 to 300 µm depending on grinder, machine and coffee. That fineness is what lets 9 bars of pressure extract the necessary solubles (around 18-22 % extraction yield) in 25-30 seconds while keeping enough puck resistance to build crema. Too fine and the water stalls (choked shot, 40+ seconds, dry bitterness); too coarse and it races (gushy shot in 15 s, watery and sour under-extraction).

Precision calls for the right grinder. An espresso-capable conic or flat burr grinder (Niche Zero, Eureka Mignon, Baratza Sette 270Wi, Mazzer Mini for home; Mazzer Robur, Mythos One for commercial) offers 40 to 300 steps between very fine and slightly coarser espresso territory. A blade grinder or a filter-only burr (Baratza Encore, Wilfa Svart) won't reach the consistent fineness needed — those are built for pourover. A grinder without micro-adjustment can't handle the daily dialling required when you change origin or ambient conditions shift.

Dialling is the adjustment process. Start from an estimated setting, weigh 18 g of beans (standard double basket), grind, tamp into the portafilter, pull the shot. If it comes out in 22 s with 36 g in the cup, you're there. If it runs in 18 s, tighten by one step. If it runs 40 s, open one step. Change one variable at a time, pull again, adjust. Three to five shots usually lock a coffee in. Less obvious: espresso grind drifts with ambient humidity — the same setting can pour in 25 s on a humid August day and 32 s in dry January, with aromatic loss if you don't retune.

Granulometrically, the spread matters as much as the median. A good espresso grinder delivers a relatively tight distribution around the target, with few 'fines' (<50 µm) and few 'boulders' (>500 µm). Excessive fines create channelling — preferential paths where water rushes through, over-extracting one zone and under-extracting the rest. That is why competition baristas use a WDT tool (Weiss Distribution Technique, fine needles that stir the bed) before tamping. In specialty shops in Brussels, Ghent or Antwerp, investment in a quality espresso grinder (€2,000-6,000) is viewed as more critical than the machine itself.

Espresso grind — reference