Espresso Dial-in Without a Stopwatch – The CCC Method

Most dial-in guides tell you your espresso should run for 25 to 30 seconds and that you should adjust the grind until it does. We don't run a stopwatch at all – and the grind size isn't our fine-tuning tool either. We take it to the extraction maximum once, leave it there, and then fine-tune with the dose.

That sounds like heresy at first. But it's exactly what one of the most-cited scientific papers on espresso recommends. In this article, we explain how we dial in at the Coffee Coaching Club, why we do it this way – and where the research draws a clear line for us, one we take seriously.

And as always with us: this is our method, not the law. If you're happy with a stopwatch, your cup isn't one bit worse for it.

What does dial-in mean for espresso?

Dialling in means adjusting a new coffee at the grinder and in the recipe until the espresso tastes good. At its core, you're changing three things: the amount of coffee you weigh in, the amount of espresso that comes out, and the grind size. Everything else – temperature, pressure, shot time – is either fixed or follows on its own.

The reason dial-in is needed at all: every coffee behaves differently. Roast level, age, density and processing change how quickly the water runs through and how easily the aromas dissolve. A setting that was perfect for your last bag can be completely off with the new one.

Our method works in two stages: first the grind size to the maximum, then the dose for fine-tuning. Both are described in detail below.

Why do we leave out the stopwatch when dialling in?

Because in espresso, time is a result, not something you adjust. It tells you afterwards how the coffee bed behaved – but you can't set it directly, only indirectly through the grind size. If you steer towards a number of seconds, you're optimising for a measurement instead of for taste.

We didn't come up with this approach ourselves. In 2020, a research team including Michael Cameron and Christopher Hendon published a mathematical model of espresso extraction in the journal Matter and tested it experimentally. The authors' recommendation is unambiguous.

In plain English: leave out the shot time and control how much dissolves from the grounds (extraction yield) using only the mass of coffee and the mass of water. That's exactly what we do – and for us, the mass of coffee is actually the more important of the two levers. The same paper also suggests that the common 20-to-30-second guideline is partly responsible for many baristas working with grind settings at which the coffee bed partially clogs and the water flows through it unevenly.

Which ratio do we use – and why only double shots?

We mostly stay between 1:1.5 and 1:2 – that is, 16 grams of coffee to 24 to 32 grams of espresso. That's shorter than the often-quoted standard of 1:2 and makes for a denser, more syrupy cup. We control it exclusively with the scale: coffee weighed in versus espresso out, both in grams.

The short ratio is directly linked to our fine grind. At the same grind size, less water extracts less – so if you pull short, you have to grind finer to reach the same extraction yield. That's why our two choices aren't two separate preferences, but two halves of the same decision.

For context: the standard recipe in the study by Cameron et al. was 20 grams of coffee to 40 grams of beverage, i.e. 1:2. On average, we're below that. What matters is that the output is measured by weight, not by eye: espresso foams, the crema is deceptive, and two cups that look equally full can differ by several grams. Without a scale under the cup, this method simply doesn't work.

We pull double shots only, and the reason is arithmetic. The same absolute inaccuracy when weighing in or when stopping at the output weight weighs twice as heavily on a small dose as on a large one. Because the dose is our fine-tuning tool, a single basket would be a particularly poor instrument: we'd be adjusting precisely the variable that's least accurate there. On top of that, a shallow coffee bed offers the water less resistance, and channels break through more quickly.

We don't know of any peer-reviewed study on the advantage of double shots over singles – the maths of the relative dosing error holds up; the argument about bed geometry is practical experience from everyday work behind the machine.

Why do we dose between 14 and 18 grams?

For us, 14 to 18 grams isn't a range we settled on for lack of a better idea – it's the working range of our fine-tuning tool. Because the grind size is at the maximum after stage one and stays there, the dose is the variable we adjust from then on – in small steps, within those four grams.

The limits come from physics: at the lower end, the relative dosing error limits the range; at the upper end, the space in the basket does. If the bed is too high, the water has too little room above it, and the puck gets pressed against the group head during the shot.

EstimateThe range of 14 to 18 grams and our ratio of 1:1.5 to 1:2 are empirical values from our courses and our day-to-day operation – estimated, not measured. With a different basket, a different coffee and a different machine, your range may lie elsewhere.

That the dose really is a lever and not just a quantity is shown by the same study by Cameron et al.: 15 instead of 20 grams only landed back at the same extraction yield once the grind size had been adjusted. So when you change the dose, you move within the extraction landscape – and that's exactly what we make use of. According to the authors, a café that reduced its dose by 25 per cent saved US$0.13 per drink along the way, extrapolated to US$3,620 a year – an extrapolation by the authors that we haven't recalculated ourselves.

To be honest: in the study, the smaller dose went hand in hand with a coarser grind, not a finer one. The finding supports the dose being an effective lever – not automatically our choice of grind size.

How fine do we grind – and where is the limit?

We grind fine – right up to the extraction maximum. Grinding finer means more surface area, more resistance and more dissolved substance – and because we don't have to steer towards a shot time, we can go finer than someone who wants their shot done in 25 seconds. Only together with our short ratio does the picture become complete: little water needs a lot of surface area.

But there's a point where it tips over, and we take it seriously. The same paper by Cameron et al. found a maximum: extraction yield rises as the grind gets finer – up to a peak. Beyond that, it falls again, because parts of the coffee bed clog and the water seeks out channels. The authors speak of “inhomogeneous flow […] resulting in poor reproducibility and wasted raw material”.

That's how we understand “grinding very fine”: not as “ever finer”, but as “as fine as possible without overshooting the maximum”. The maximum is the guardrail, not the enemy. If you work without a stopwatch, you get closer to that point – and so you need to know it all the better.

And once it's found, it stays put. That's the real difference from the usual approach: for us, grind size isn't a dial that gets turned constantly during the day, but a setting determined once per coffee. From then on, fine-tuning happens through the dose.

For context: in the study, the peak was at a specific scale number on a Mahlkönig EK 43. That number can't be transferred to any other grinder. You have to find out where your maximum lies on your own grinder – and it shifts when you change the ratio.

Besides fineness, uniformity matters. A paper by Uman and colleagues in Scientific Reports showed that colder beans produce not only smaller particles but also a narrower distribution – between room temperature and −196 °C, the most common particle diameter dropped by 31 per cent, with the biggest jump already happening between room temperature and −19 °C. The authors conclude that the greater uniformity mainly prevents bean material from ending up unextracted in the waste.

How do you find your own yield maximum?

That's stage one, and it's done with the grind size. You keep the dose and output fixed and change only the grind – finer, step by step. As long as the espresso gets sweeter, denser and rounder with each step, you're on the rising side of the curve. As soon as it turns hollow, harsh or varies from shot to shot, you've gone past the peak. Then you go back one step – and leave the grinder alone.

If you'd rather measure than taste, you need a refractometer. You calculate the extraction yield like this: yield in per cent equals TDS in per cent times beverage mass in grams, divided by coffee mass in grams. With 16 grams of coffee, 32 grams of espresso and 10 per cent TDS, that would be 20 per cent – a worked example with an assumed TDS value, not a measurement on your machine. You'll find measuring devices for this at Apax Lab.

The decisive signal, though, isn't the peak value but the spread. If three shots in a row taste noticeably different even though you haven't changed anything, the grind is too fine – no matter how good the best of those three shots was.

How do you then fine-tune with the dose?

That's stage two. The grind size is set, and from now on you change only the dose – in half-gram steps, within 14 to 18 grams. The advantage: you can always go back to exactly where it tasted good, because a number on the scale is unambiguous, while a position on the grinder dial often isn't.

Path A: the ratio stays, the output moves with it. 16 to 32 grams becomes 17 to 34 grams. The strength in the cup stays similar, but the bed gets deeper, resistance rises, and the water takes longer to pass through the same amount of ground coffee. This is the path to take if you like the character of the cup and just want a rounder extraction.

Path B: the output stays, the ratio moves. 16 to 32 grams becomes 17 to 32 grams, i.e. 1:1.9. This shifts concentration and yield directly: more coffee for the same amount of beverage gives a denser, more concentrated cup. This is the path to take if the cup seems too thin or not focused enough.

Which one we choose, we decide case by case – depending on what the cup is currently missing. The only important thing is to stick to one path per round; otherwise, you won't know in the end which of the two changes made the difference.

How do you dial in, step by step?

What should you do if your espresso channels?

Channeling means the water forces a path of low resistance through the puck instead of flowing evenly through the whole bed. Part of the coffee gets over-extracted while the rest stays under-extracted – and the cup tastes bitter and thin at the same time. You can spot it by spurting jets, holes in the puck, and two identically prepared shots tasting different.

Turning up the pressure hardly helps here. A paper by Waszkiewicz and colleagues, published in Physics of Fluids in June 2026, measured how much water runs through the puck at pressures of around 1 to 12 bar at the basket. The result: at low pressure, flow still rises almost proportionally; above that, it levels off. The reason is that the coffee bed compresses under pressure instead of staying rigid – the authors call this poroelastic. So beyond a certain point, more pressure brings hardly any more flow.

Two caveats we want to mention: the study's values are equilibrium values after 110 to 120 seconds of continuous brewing, not from a normal 30-second shot. And the paper doesn't say that channeling follows directly from this – that's our interpretation. What's established is the link between pressure and flow, not the one between pressure and channel formation.

What actually helps is puck preparation: break up clumps with a WDT tool, distribute evenly, compress level with a precision tamper and use a cleanly made basket – why that matters is explained in our article on IMS precision filter baskets. You'll find suitable tools from Normcore and in our Barista Equipment range.

What does a spritz of water before grinding do?

A fine spritz of water on the beans before grinding – known in the coffee scene as the Ross Droplet Technique – reduces static and with it the clumping in the grounds. It's not a kitchen trick, but the subject of a paper by Méndez Harper and colleagues, published in 2023, also in Matter.

The authors found that fewer clumps make for a more densely packed coffee bed, that the water therefore flows through more slowly, and that the concentration of the finished espresso rises by up to 15 per cent with the same dry coffee dose. Christopher Hendon sums it up like this: raising the concentration by 10 to 15 per cent at the same dose has major implications for cost and quality. Shot-to-shot repeatability also improved.

For us, it's the natural partner to fine grinding: the finer you grind, the more the grounds become charged and the more clumps form – so exactly where the effect helps most. And because we fine-tune with the dose, anything that reduces the spread between two identical doses helps.

The paper doesn't give a universally valid amount of water. In practice, a single fine spritz on the weighed beans is enough; any more water has no place in a grinder.

What does this mean for you at home?

You don't need elaborate equipment for this, just two things: a scale that responds quickly enough, and a grinder with fine adjustment steps. Everything else is practice. A single-dose grinder suits this method particularly well, because with every shot you grind exactly the amount you've weighed in – and for us, the dose is the variable that matters.

And then the rule we always go by applies: this is our method because it gives us the most reliable cups. If your espresso tastes better with a stopwatch, with a single basket or with a completely different ratio, then you're right, and we have a method. United by Coffee.

If you'd rather go through this together at the machine: that's exactly what we do in our showrooms in Bern and Zurich – in the barista course in Zurich, in the workshops or at a consultation appointment.

Frequently asked questions about espresso dial-in

Should I adjust the grind size or the dose when dialling in?

We do both – but one after the other. First, you take the grind size to the extraction maximum once and leave it there. After that, you fine-tune only with the dose, in half-gram steps. The advantage: a number on the scale is clearly repeatable, while a position on the grinder dial often isn't.

How long does an espresso have to run?

In our view, it doesn't “have to” at all. We steer by dose and output in grams and let the shot time be what it is – a measurement. In Matter (2020), Cameron et al. explicitly recommend ignoring brew time and steering only by the mass of coffee and water.

How much coffee goes into a double shot?

We work with 14 to 18 grams, and for us this range is the fine-tuning range: because the grind size stays put once it's set, the dose is the variable we adjust from then on. At the lower end, the relative dosing error limits the range; at the upper end, the space in the basket does.

What is the brew ratio for espresso?

The brew ratio is the amount of coffee weighed in relative to the amount of espresso out, both in grams. We mostly stay between 1:1.5 and 1:2; with a 16-gram dose, that's 24 to 32 grams of espresso. Shorter gets denser and more syrupy, longer gets clearer and lighter.

Why does my espresso taste sour?

Usually it's under-extracted: the grind is too coarse, the water runs through too quickly, or the output is too small. Grind one step finer and keep the ratio unchanged. Not all acidity is a flaw, though – light roasts naturally bring fruity acidity with them.

What is channeling and how do I recognise it?

With channeling, the water finds paths of low resistance through the puck instead of flowing evenly through the bed. You recognise it by spurting or uneven streams, craters in the knocked-out puck, and identically prepared shots tasting different. The cause is almost always puck preparation, not pressure.

Should I grind finer or coarser for espresso?

Finer increases extraction – but only up to a maximum. Cameron et al. found a peak beyond which yield and repeatability drop again, because the bed clogs in places. We deliberately grind up to this maximum, partly because our short ratio of 1:1.5 to 1:2 calls for it – but we go back one step as soon as the shots start to diverge.

How do I calculate extraction yield?

Extraction yield in per cent equals TDS in per cent times beverage mass in grams, divided by coffee mass in grams. You measure the TDS value with a refractometer. With 16 grams of coffee, 32 grams of espresso and 10 per cent TDS, that gives a yield of 20 per cent – calculated with an assumed TDS value, not measured.

Sources

• M. I. Cameron, D. Morisco, D. Hofstetter, E. Uman, J. Wilkinson, Z. C. Kennedy, S. A. Fontenot, W. T. Lee, C. H. Hendon, J. M. Foster: Systematically Improving Espresso: Insights from Mathematical Modeling and Experiment. Matter 2 (2020) 631–648.
• J. Méndez Harper et al.: Moisture-controlled triboelectrification during coffee grinding. Matter (2023), DOI 10.1016/j.matt.2023.11.005.
• R. Waszkiewicz, F. Myck, Ł. Białas, M. Puciata-Mroczynska, M. Dzikowski, P. Szymczak, M. Lisicki: Under pressure: Poroelastic regulation of flow in espresso brewing. Physics of Fluids 38 (2026), issue 6, article 063113, DOI 10.1063/5.0319611. Checked by us: the paper exists, is peer-reviewed and was published in June 2026.
• Istituto Nazionale Espresso Italiano: The Certified Italian Espresso and Cappuccino. 7 g ± 0.5 g ground coffee, 25 ml ± 2.5 ml in the cup including crema, 9 bar ± 1, 88 °C ± 2.
• CEME/ULKA, vibration pump type E datasheet: 650 ml/min at 0 bar, 300 ml/min at 8 bar, 210 ml/min at 10 bar, 60 ml/min at 14 bar, 0 ml/min at 15 bar.
• E. Uman, M. Colonna-Dashwood et al.: The effect of bean origin and temperature on grinding roasted coffee. Scientific Reports 6 (2016) 24483.

If you want to apply the same way of thinking to filter coffee, you'll find it in our V60 guide. And if you want to know what sets espresso, ristretto and lungo apart, we have separate articles on espresso and ristretto.