What grind size for moka pot?

For a moka pot, aim at a medium-fine grind around 350-450 µm — coarser than espresso, finer than V60. The texture sits close to fine table salt or powdered sugar. Too fine and the water stalls, scorching the coffee; too coarse and water races through, leaving extraction underdeveloped.

The moka pot, invented in 1933 by Alfonso Bialetti, works at an intermediate pressure of 1.5 to 2 bars built by steam. That modest pressure, compared with the 9 bars of espresso, calls for a different grind — too fine and water cannot clear the basket before pressure climbs dangerously (the safety valve may open). The target sits around 400 µm, between espresso (250 µm) and V60 (600 µm). Visually, the grind crushes slightly between fingers without feeling powdery, close to fine table salt or powdered sugar that lost its icy edge.

Dose matters as much as grind. Fill the basket so the coffee mounds just a bit above the rim, but never tamp — unlike espresso where tamping is essential, moka coffee is never tamped. Tamping would add so much resistance that steam would channel around the bed along the walls, producing a thin or failed brew. Fill with cold water up to (never above) the safety valve, drop the basket in without pressing, screw the two halves together gently, put on medium heat.

Roast choice matters as much as grind. Italian tradition calls for a darker roast, often an Arabica-Robusta blend (70/30 or 80/20), that holds up to the 100 °C end-of-brew temperature. A light-roast specialty single origin, though usable, tends to over-extract in a moka and under-delivers compared with V60 or espresso; a few Belgian specialty roasters offer 'moka-friendly' medium-roast blends for those who still favour the format. Ratio lands around 1:10 to 1:12 water-to-coffee — roughly 15-18 g for a 3-cup moka (around 150 ml of water).

One classic pitfall: grinding as fine as espresso. A 250 µm grind in a moka typically triggers three issues — stalled extraction for 2-3 minutes, water temperature climbing past 100 °C and scorching aromatics, dry bitterness in the cup. Conversely, a French-press-coarse 800 µm grind gives a thin, watery brew because water runs through too fast to extract. Watching the flow is a good cue: a steady dark-brown stream turning pale ('pale blonding') over 30-45 seconds signals a correct grind. In Belgium, where the moka is everywhere in kitchens — Italian-heritage or simply an heirloom Bialetti — most households use pre-ground 'for moka' coffee from supermarkets, which is acceptable but gains a lot from fresh grinding.

Moka grind — technical reference