Pressure Profiling Simulator (Espresso)
Pressure is the invisible lever in espresso. Play through how pre-infusion, peak pressure and a declining profile shape your shot — from the crema to the clarity. And see when too much pressure tears open channels.
The sliders: Pre-infusion is a switch, on or off. Peak pressure has a real unit: 4 to 12 bar in steps of 0.5 bar. Profile offers three shapes — declining, flat, rising. Worth knowing: in the calculation, this choice changes only two results, namely clarity / sweetness and bitterness. Flow, crema, extraction and channeling risk are not affected by it. Grind size is a relative scale from 0 to 100 with no unit: 0 is coarse, 100 is very fine. These are not microns and not the markings on your grinder — the number only describes how much resistance the coffee bed puts up against the water.
The results: Channeling risk, evenness, extraction, crema, clarity / sweetness and bitterness are scores from 0 to 100, not measurements and not lab results. They show you the direction your shot is moving in, not how it will taste. “Evenness” is not a value of its own, simply 100 minus the channeling risk — the same number seen from the other side. The needle on the pressure gauge and the “pressure over time” curve are calculated too: they show what your slider setting produces in the model — a calculated value, not a measurement on your machine.
The basis — and a contradiction we want to be upfront about: The 9 bar comes from the Italian definition of espresso (INEI); the idea that pre-infusion and an even puck reduce channeling is consistent with the espresso modelling by Cameron and Hendon (2020). The text further down explicitly puts the 9 bar into perspective as a tradition rather than an optimum — the calculation does not. It measures flow strictly against 9 bar (9 bar is the 100 per cent reference) and rates 8 to 10 bar as “in the window”. So if you set the slider to 6 or 7 bar, you get a stricter verdict than the evidence justifies — many people today deliberately work with 6 to 7 bar and are very happy with the results. So read this tool as a clean representation of the Italian school, not as proof that it is right. We would rather say this clearly than quietly let the number stand as the truth.
This is a simulator. It works with a simplified model and shows you how things relate — not measurements and not a promise. What ends up in your cup depends on your machine, your water, your beans and the way you work.
Our recommendations are based on experience from advice, courses and the showroom. They are non-binding and come with no guarantee. We accept no liability for any damage resulting from their use. If in doubt, follow what your manufacturer says in the user manual.
The Pressure Profiling Simulator is loading… If nothing appears, please reload the page — or view espresso machines.
Straight to the results: The six values shown as bars below the image are scores from 0 to 100 from our model — not measurements. The figures in bar shown in the image are also calculated by the model and are not a measurement on your machine: the needle and the curve draw what your slider produces in the model — not the pressure actually present in your group head.
Pre-infusion, peak pressure and profile
Pressure drives the water through the coffee puck. How fast depends on the resistance of the coffee bed (finer grind = more resistance). A pre-infusion — a short pre-brew at low pressure — wets the puck more evenly before full pressure arrives. This lowers the risk of channels (channeling), through which water shoots unevenly, over-extracting one part of the coffee and under-extracting another.
Peak pressure shapes crema and flow. The Italian espresso standard is 9 bar ± 1 — but that is a tradition from the spring-lever machine, not a physically proven optimum. Too little pressure extracts weakly; too much can compress the puck and encourage channels. A declining profile (start high, taper off gently) — the kind classic lever machines deliver by their very nature — often takes bitterness out towards the end.
The Italian association INEI describes certified espresso with five figures. We have checked them, and they are correct: dose 7 g ± 0.5, water temperature at the group head outlet 88 °C ± 2, pressure 9 bar ± 1, extraction time 25 s ± 5 and 25 ml ± 2.5 in the cup, crema included (plus a drinking temperature of 67 °C ± 3). This is a product definition, not a constant of nature: it sets out what may be called “espresso” in Italy — not what tastes best.
A contradiction we want to be upfront about: This section puts the 9 bar into perspective as a tradition. The simulator above does not — it normalises flow strictly to 9 bar and calls 8 to 10 bar “in the window”. So if you work with 6 or 7 bar, you get a stricter verdict than is justified. Both stand side by side here because we do not want to quietly gloss over the tool’s calculation logic.
Important from a CCC point of view: pressure is a tool, not an end in itself. We choose by taste, weight and ratio — not by the clock. There is no right or wrong; the cup decides.
Sources: Istituto Nazionale Espresso Italiano (certified Italian espresso: 7 g ± 0.5, 88 °C ± 2 at the group outlet, 9 bar ± 1, 25 s ± 5, 25 ml ± 2.5 including crema — checked by us); Cameron, Hendon et al. (2020), “Systematically Improving Espresso”, Matter 2, 631–648 (extraction evenness & channeling).
Controlling pressure
Pre-infusion, pressure profile or classic 9 bar — how much control you have depends on the machine. For maximum, direct pressure control, you build the profile by hand on a Flair lever machine; among electric machines, paddle and profiling models such as La Marzocco offer the finest control. You will find an overview of all espresso machines here. The Extraction Simulator shows how pressure interacts with grind size and ratio; and an even puck starts in the Puck Prep Workshop.
Frequently asked questions
What does pressure profiling mean in espresso?
Pressure profiling means deliberately changing the pressure over the course of the extraction instead of keeping it constant — for example with a pre-infusion at low pressure, a peak pressure and a declining finish. This lets you influence evenness, crema and flavour.
How many bar does an espresso need?
The Italian standard (INEI) is 9 bar ± 1. That is a tradition from the spring-lever machine, not a physically proven optimum. Many people deliberately experiment with 6 to 7 bar — what matters is the taste in the cup. Bear in mind: the simulator above uses 9 bar as its reference and only rates 8 to 10 bar as “in the window”. So it shows the Italian school, not the whole truth.
What does a pre-infusion do?
A pre-infusion wets the puck evenly at low pressure before full pressure arrives. This lowers the risk of channels and makes the extraction more even — especially with lighter roasts.
Does higher pressure mean more extraction?
Not automatically. Too much pressure can compress the puck and encourage channels that extract unevenly. More pressure means more crema, but not necessarily better flavour — weight, ratio and taste are what decide.
You will find all our interactive tools gathered together in our coffee tools.
