A moka pot sits between espresso and filter, and so does its grind: roughly table salt, finer than a drip machine wants and clearly coarser than espresso.
Why not espresso-fine
A moka pot generates around one to two bars of pressure, not nine. An espresso-fine bed resists far more than that, so steam builds up behind it and forces through in violent bursts — the sputtering everyone recognises. Those bursts are steam rather than water, and steam extracts nothing but bitterness.
If your pot spits and jumps, go coarser. It is almost always this.
Why not filter-coarse
Too coarse and water passes through with little resistance, giving a weak, thin brew that wastes good coffee.
The other things that matter more than you expect
Fill the basket level and do not tamp. A moka basket is filled to the top and swept flat. Tamping restricts flow at a pressure that cannot overcome it, which produces exactly the sputtering described above.
Fill the pot to its rating. The basket needs a full bed for water to pass through evenly. A 6-cup pot brewing 3 cups over-extracts badly.
Use pre-boiled water and low heat. This matters more than grind size. Cold water leaves the pot on the flame for minutes while the metal and the coffee cook before brewing even starts, and that is where most moka bitterness comes from.
If you buy pre-ground
Look for coffee sold specifically for moka pots, which is ground for this range. Coffee sold as “espresso ground” is usually too fine, and supermarket filter grind is usually too coarse.
Questions people actually ask
Should the coffee be heaped or level?
Level. Fill the funnel to the top and sweep it flat with a finger. A heaped basket presses against the upper chamber when you screw it together and restricts flow.
Why does my moka pot spit?
Too fine, tamped, or too much heat — in that order of likelihood. All three restrict flow so that steam rather than water forces through.
Last reviewed 8 August 2026