How to dial in an espresso grinder?

Dialling in an espresso grinder means finding the exact grind setting that produces a balanced espresso within the target extraction time — typically 25 to 35 seconds for 18 g of coffee yielding 36–40 g of liquid. If the shot runs too fast (< 20 s): grind is too coarse, go finer. If too slow (> 40 s): grind is too fine, go coarser. Each adjustment should be made in small increments, and the grinder must be purged after each change to avoid mixing two different grind sizes.

Dialling in is the daily or weekly procedure that allows any barista to maintain consistent espresso quality. It is made necessary by two factors: coffee ageing (a bag opened 3 weeks ago extracts faster than freshly opened beans, since CO2 degassing is complete) and variations in ambient temperature and humidity (which slightly change the coffee's absorption properties).

The first step is to establish reference parameters. For a standard espresso, the baseline recipe is: 18 g of coffee in (dose), 36–40 g of coffee out (extracted liquid weight), in 28–32 seconds, at 9 bar, at approximately 93 °C. This 1:2 ratio (dose:liquid) is a starting point, not an absolute rule. Some modern recipes use ratios of 1:2.5 or even 1:3 for light roasts.

The concrete procedure starts with a calibration pull. Without changing the grind, pull a first shot and observe: flow time, stream colour, crema texture. If the shot runs in 20 seconds with a pale, watery stream = too coarse. If it trickles for 45 seconds with very little liquid = too fine. Adjust by one or two steps in the appropriate direction, purge the transition (about 2–3 g of coffee to flush old grind from the path), and pull again.

Tasting is essential at each step. The time may be in window but the coffee can still be sour (under-extracted) or bitter (over-extracted). Learning to read both pieces of information together — time + taste — is the core skill. Correct time with sour taste often indicates consistent grind but temperature too low, or a light roast that needs a finer grind than the time window alone would suggest.

Stepped-adjustment grinders require discrete moves — one step corresponds to a variation of a few to a few dozen microns depending on the grinder. Stepless grinders allow infinitely fine adjustments, more precise but harder to memorise. Keeping a log of grind settings (on paper or in an app) is essential for any barista working several different coffees or returning after a break.

Dial-in diagnostic: reading an espresso shot

A Step-by-Step Protocol for Dialling In Any Espresso Grinder

Dialling in an espresso grinder is the process of finding the grind size that produces a shot within your target parameters - typically 25-30 seconds extraction time for a 1:2 ratio (18 g in, 36 g out) at 9 bars. The challenge is that the correct setting changes with every new bag of coffee, because roast level, bean density, processing method, and freshness all affect how quickly water passes through the coffee bed. A light roast needs a finer grind than a dark roast of the same dose, because the cell walls are denser and resist water flow. A coffee three days off roast needs a different setting than the same coffee three weeks off roast, as degassing CO2 affects puck density.

The standard protocol: start with a medium grind setting, pull a shot, and time the yield. If 36 g of liquid takes less than 22 seconds, grind finer. If it takes more than 32 seconds, grind coarser. Adjust in small increments - one click or one minor step on a stepless grinder - and purge 2-3 grams of grounds after each adjustment to clear the burr chamber of old-setting grounds before pulling your test shot. Taste each shot rather than just measuring it: a shot that hits 27 seconds but tastes hollow and acidic is under-extracted (grind finer), while one that takes 29 seconds but tastes bitter and drying is over-extracted (grind coarser). Time and taste together give a complete picture.

Practical Recommendations

Keep a logbook: date, coffee name and roast date, dose, yield, time, grind setting, and a one-sentence tasting note. After three or four bags from the same roaster, you will notice patterns - their light roasts always start two clicks finer than their mediums, or their naturals always need a coarser grind than their washed coffees. This institutional knowledge makes dialling in faster each time. For a new bag, start at the setting you used for the most similar previous coffee rather than from scratch - you will typically be within two adjustments of your target rather than ten.