How to Dial In a Coffee Grinder: A Beginner’s Guide for Coffee Shops

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July 20, 2026

On July 20, 2026

Last updated: July 2026

Dialling in a coffee grinder means adjusting it until every espresso shot tastes right. This beginner’s guide walks coffee shop owners through the whole routine in seven simple steps.

The widely accepted starting recipe is 18g of ground coffee in, 36g of espresso out, in 25-30 seconds. Dialling in against that recipe is the standard morning routine in almost every commercial coffee shop, on any grinder from £449 upwards.

In 30 seconds:

Weigh 18g of coffee in. Aim for 36g of espresso out, in 25-30 seconds.
Shot fast and sour? Grind finer. Shot slow and bitter? Grind coarser.
Change one thing at a time — the grind, never the dose.
Purge a few grams after every adjustment.
Re-check every morning and with every new bag of beans.

The biggest beginner mistake? Changing the dose and the grind at the same time. When the next shot improves, you won’t know which change fixed it. Fix the dose at 18g and let the grind setting do all the work.

Why bother? An undialled grinder serves sour or bitter coffee all day. Customers rarely complain — they just don’t come back. Five minutes each morning protects every drink you sell.

What you’ll need

Your espresso machine, switched on and fully warmed up (allow 15-20 minutes).
A commercial burr grinder with beans in the hopper.
Small scales that read to 0.1g — from £15.
A shot timer, or the timer on your phone.
Fresh beans, ideally roasted 7-28 days ago.
A cloth and a tray for spent test shots.

Jargon buster

Dialling in — adjusting the grinder until shots hit your recipe.
Dose — the weight of ground coffee in the basket. We use 18g.
Yield — the weight of espresso in the cup. We aim for 36g.
Extraction — how much flavour the water pulls from the coffee. Too little tastes sour; too much tastes bitter.
Burrs — the two cutting discs inside the grinder that crush the beans. Bigger burrs grind faster and cooler.
On-demand — a grinder that grinds fresh for each shot at the press of a button.
Doser — a grinder that grinds into a chamber, then dispenses with a pull lever.
Purge — grinding a few grams into the bin so old grounds clear the burrs after an adjustment.

Step 1: Start clean and fresh

Clean the burrs and hopper, then fill with fresh beans roasted 7-28 days ago. Old grounds stuck in the burrs turn rancid and make every shot taste bitter.

Keep the hopper at least a third full while you work. A near-empty hopper feeds beans unevenly, so the grind wanders. If you haven’t cleaned the machine side recently, our guide on how to clean and descale a commercial coffee machine covers the full routine.

Step 2: Set your dose

Weigh 18g of ground coffee into the double basket and keep that dose fixed. Put the empty portafilter on the scales, zero them, grind, then weigh.

On an on-demand grinder, adjust the grind-time button until it delivers 18g. A Fracino F4 Series On Demand grinder (from £699) grinds a single 7g dose in about 3.5 seconds. A double dose lands in around 9 seconds. Once set, the button gives you the same dose all day.

Step 3: Pick a starting grind setting

Set the grinder to the middle of its espresso range and grind a small purge. Most commercial grinders use a micrometric collar — a threaded ring that moves the burrs closer or further apart in tiny steps. Tiny is the key word: one small step changes shot time by several seconds.

Turning towards “fine” slows the shot down. Turning towards “coarse” speeds it up. That’s the only rule you need to remember.

Step 4: Pull a timed test shot

Pull a shot aiming for 36g of espresso in 25-30 seconds. Put a cup on the scales under the spouts, zero them, and start the timer as you start the shot.

Stop the shot at 36g and note the time. Under 25 seconds means too coarse. Over 30 seconds means too fine. Between the two? Taste it before you touch anything.

Step 5: Taste and adjust the grind

If the shot ran fast and tastes sour, go one step finer; slow and bitter, one step coarser. Sourness means the water rushed through and took too little flavour. Bitterness means it dripped through and took too much.

Make one small adjustment, purge a few grams, and pull another timed shot. Expect two to four test shots before it lands. That’s normal, not failure.

Step 6: Lock in the setting

Note the final grind setting, purge a few grams, and brief the team. Write the day’s numbers where every barista can see them: dose, yield, and time.

Every barista on shift should pull to the same recipe. If two people “prefer” different settings, your customers get two different coffees.

Step 7: Re-check through the day

Pull a timed check shot mid-shift and adjust one step if the time has drifted. Beans dry out as the day goes on, and warm or humid weather shifts the grind too.

A 30-second check at 11am saves a whole afternoon of drifting shots. New bag of beans? Treat it as a fresh dial-in from Step 4.

Common mistakes to avoid

Changing dose and grind together. You’ll never know which one fixed the shot. Fix the dose; move the grind.
Adjusting by taste alone. Taste tells you what’s wrong; the timer tells you how far out you are. Use both.
Skipping the purge. After an adjustment, the burrs still hold grounds at the old setting. Purge or your next test lies to you.
Big adjustments. One small step at a time. Two steps often jumps straight past the sweet spot.
Blaming the beans for dirty burrs. Coffee oils go stale inside the grinder. Clean burrs weekly before you change anything else.
Running the hopper empty. Light hopper, uneven feed, wandering grind. Keep it topped up.

When dialling in won’t fix it

Worn burrs. Burrs are consumable. Dull burrs crush instead of cut, producing fluffy, uneven grounds that never dial in cleanly. If shot times jump around at the same setting, worn burrs are the usual suspect.

Machine problems. Low pressure, scale in the boiler, or a blocked shower screen all mimic a bad grind. If the grinder checks out, look at the machine side next.

The wrong grinder for your volume. A small-burr grinder overheats in a busy queue, and hot burrs shift the grind. Our commercial coffee grinder buying guide for coffee shops explains which burr size and format suits your counter.

Choosing a grinder that’s easy to dial in

On-demand grinders are the easiest for beginners: fresh grounds per shot, so every adjustment shows up straight away. For a small café, the Fracino F2 Specialty on-demand grinder (from £449) pairs a 50mm burr set with simple micrometric adjustment. Busier counters suit larger 58-65mm burr models that grind faster and cooler.

You can compare hopper sizes, burr sizes, and dosing formats across the full coffee grinders range.

Frequently asked questions

What does “dialling in” a coffee grinder mean?

Dialling in means adjusting your grinder until espresso shots hit a set recipe — typically 18g of coffee in, 36g out, in 25-30 seconds. You pull test shots, taste them, and nudge the grind finer or coarser. Most coffee shops dial in every morning. It usually takes two to four test shots and five minutes.

How often should I dial in my coffee grinder?

Check the grind at the start of every day, and again whenever you open a new bag of beans. Beans age and weather changes, so yesterday’s setting drifts. A quick timed test shot mid-morning catches most drift. Full dial-ins are usually only needed for new beans or after cleaning the burrs.

Why does my espresso taste sour?

Sour espresso is usually under-extracted — the water ran through the coffee too fast. If your 36g shot finishes quicker than 25 seconds, the grind is too coarse. Move the grinder one small step finer, purge a few grams, and pull another test shot. Repeat until the shot lands in the 25-30 second window.

Why does my espresso taste bitter?

Bitter espresso is usually over-extracted — the water dripped through too slowly. If your shot takes longer than 30 seconds, the grind is too fine. Move the grinder one small step coarser, purge, and test again. Dirty burrs also cause bitterness, so clean the grinder before blaming the beans.

What is a good espresso recipe for a coffee shop?

The standard commercial recipe is a 1:2 ratio — 18g of ground coffee in the double basket, 36g of espresso in the cup, in 25-30 seconds. It is widely used because it suits most medium roasts and milk drinks. Once dialled in, every barista on shift should follow the same numbers.

Should I change the dose or the grind setting?

Keep the dose fixed and adjust the grind. Changing both at once makes it impossible to know which change fixed the shot. Weigh 18g into the basket every time, then use the grind adjustment alone to control shot time. Only revisit the dose if you switch baskets or change your menu.

How much coffee is wasted dialling in?

Expect two to four test shots per dial-in — roughly 40-80g of beans, or £1-£2 a day at typical wholesale prices. That is the cheapest quality control a coffee shop can buy. One badly dialled morning wastes far more in undrinkable shots, remakes, and lost repeat custom.

Do on-demand and doser grinders dial in differently?

The method is the same: fixed dose, timed shot, small grind adjustments. On-demand grinders grind fresh for each shot, so changes show up almost immediately after a small purge. Doser grinders hold ground coffee in a chamber, so empty it after each adjustment or your next test shot uses the old grind.