Tamping compresses the coffee bed so water meets uniform resistance. Two things about it are widely misunderstood.
Pressure barely matters above a point
Coffee compacts up to a limit. Beyond roughly fifteen kilograms of force the puck is about as dense as it will get, and pushing harder achieves almost nothing measurable.
The old advice to tamp at “thirty pounds” produced a generation of sore wrists and no better coffee.
Level matters a great deal
A tilted tamp leaves one side of the puck thinner and less dense. Water finds it immediately, and you get channelling.
Watch the tamper from the side rather than pressing by feel, or use a self-levelling tamper with a collar that rests on the basket rim.
Consistency matters most
Whatever pressure you use, use it every time. Espresso improves by changing one variable at a time, and a tamp that varies is a variable you cannot see.
That is the honest case for a calibrated spring tamper: not that 25 lb is correct, but that it is the same 25 lb when you are half awake.
What to fix instead
If shots are inconsistent, distribution before tamping is a far bigger lever. Stir the bed with a WDT tool. Tamping cannot fix clumps — it compresses them.
Do not knock the basket
Tapping to settle the puck after tamping cracks it, and a crack is a channel.
Last reviewed 8 August 2026