Guide · Tampers and stations
How hard should you tamp espresso?
Shots tamped at 5 to 20 kg showed no extraction difference. What matters instead: a level, complete tamp, the right tamper size and grind.
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The short answer
Tamp until the coffee stops compressing, keep the tamper level, and then stop worrying about the exact force. In the best-known controlled comparison, shots tamped at 5, 10, 15 and 20 kg showed no difference in extraction.
What the measurements show
| Source | What was compared | Result |
|---|---|---|
| Socratic Coffee (2015), independent | 5, 10, 15 and 20 kg tamps (about 12–42 lb), 10 shots each, TDS read on two refractometers | No difference in TDS across the range (p = 0.40). Brew weight, not tamp force, drove the differences |
| Decent Espresso, tamper maker | Its own compression checks | Says coffee is fully compressed at about 15 lb and more pressure is not needed. This is a vendor statement, not an independent study |
These are small studies on specific setups, and they measured strength and extraction rather than taste. They do not show that tamping force never matters. They do show that, once the coffee is compressed, adding force is not a lever worth chasing.
So why do calibrated tampers exist?
A calibrated or spring tamper clicks or bottoms out at a set force. The value is repeatability: every shot gets the same tamp, which makes it easier to change one thing at a time when you dial in. The number itself is not special. Normcore, for example, ships its spring tamper with 15, 25 and 30 lb springs and lets you choose.
If you buy one, choose it for size and levelness first. Our 30 lb calibrated tamper notes treat the "30 lb" as the seller's figure, because nobody has checked it.
What does change the shot
- A level tamp. A tilted tamp leaves one side of the puck thinner than the other, and water takes the easier path.
- A tamper that fills the basket. A loose tamper leaves an untamped ring at the edge. See the basket and tamper size guide for the size that fits your machine.
- Even distribution before tamping. Clumps and empty pockets survive the tamp. A WDT tool breaks them up.
- Grind size. Finer is not always better: a peer-reviewed study (Cameron et al., 2020) found extraction peaks and then falls at very fine settings, because water starts flowing unevenly through the puck.
A simple routine
- Distribute the grounds evenly.
- Set the tamper flat on the coffee.
- Press straight down until the coffee stops giving.
- Lift straight up without twisting the puck loose.
Then judge the shot by taste and by your scale, and adjust the grind, not the tamp.