Pre-Infusion Calculator
Pre-infusion is the secret weapon for sweeter, more even shots. Tell us your machine type and roast level — we'll suggest a pre-infusion time, pressure approach, and what to watch for in the first drips.
Pressure approach
Watch the first drips
Roast adjustment
Why pre-infusion changes the shot
Dry coffee grounds resist water. Slamming full 9-bar pressure into a dry puck finds the weakest path and punches through it — that's channeling, and it under-extracts the rest of the puck while over-extracting the channel. A low-pressure soak first wets everything evenly, so when full pressure arrives, the water flows through the whole puck instead of one highway. The payoff is sweetness and consistency, and it's most dramatic with light roasts, which are the hardest to wet evenly.
Reading the first drips
The first drips are a free grind report. After a full pre-infusion soak, drips that appear around 8–10 seconds suggest you're in a reasonable zone. Nothing by 12 seconds usually means too fine or too much coffee; drips before 5 seconds mean too coarse. What you want to see: even, syrupy beading across the whole basket, not one side streaming while the other stays dry — that's a channeling flag and a sign your puck prep needs work.
How to use this calculator
Pick the machine type closest to yours and your roast level, then hit "Calculate pre-infusion." The result is a starting point — program it in if your machine allows, or use the manual bloom trick (pump 3 seconds, pause 10–15, resume) on basic machines. Then taste: if shots are sweet but a touch dull, shorten pre-infusion; if they're bright but uneven, lengthen it. Time your shots with our shot timer to keep everything consistent.
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What does pre-infusion do to an espresso shot?
Pre-infusion wets the coffee puck at low pressure before full 9-bar extraction begins. It soaks the grounds evenly, which reduces channeling — water punching weak paths through the puck — and makes extractions more even, especially with lighter roasts that resist water.
How long should pre-infusion last?
It depends on the machine and the roast. A typical range is 3–15 seconds: shorter for dark roasts and basic machines, longer for light roasts and E61 or lever machines. Use the calculator above for a starting point, then adjust by taste.
What should the first drips tell me?
First drips are a grind readout: if the puck is fully wetted and nothing drips by ~10–12 seconds, your grind is likely too fine or your dose too high. If drips appear before 5 seconds, you're probably too coarse. Even, syrupy drips across the basket signal good puck prep.
My machine has no pre-infusion setting. Can I still do it?
Yes. The manual "bloom" trick works on almost any machine: run the pump for 3 seconds, stop for 10–15 seconds while the puck soaks, then run the shot normally. It is not as precise as a programmable stage, but it gets you most of the benefit.