By Scott Rao
Republished by ST. DION Coffee with permission.
⸻
ST. DION Introduction
Choosing the right grind setting is one of the most important — and most misunderstood — parts of brewing coffee well.
Many people want a fixed answer: What number should I use on this grinder for a V60? But as Scott Rao explains, grind setting is never universal. Dose, brewer shape, burr geometry, roast level, fines production, and even bean temperature can all change how coffee extracts and how quickly water flows through the bed.
At ST. DION, we believe great brewing comes from understanding principles, not memorizing numbers. This article is a clear guide to why grind recommendations are difficult, and how to think more intelligently about dialing in your coffee.
⸻
How to Choose a Grind Setting
I often get asked versions of:
“What grind setting would I use for a V60 and the XYZ grinder?”
There are a few problems with these questions:
I’ve usually not used that grinder.
Dose matters; the setting for a 15g V60 is much finer than that for a 30g V60.
Burr type, alignment, and sharpness may affect the optimal setting.
The amount of fines produced at a given grind setting varies for different coffees.
Given that I almost certainly haven’t used the exact combination of coffee, roast level, grinder, brewer, and dose in question, the best I can do is recommend finding the grind setting that produces the optimal total brew time for the dose and brewer in question.
Even a reply such as “set the grinder to 650 microns” is risky advice. The micron size of the particle-size-distribution peak does not take into account the percentage of fines produced, and fines have an outsized impact on flow rate through a coffee bed.
⸻
The Grinder
Twenty years ago, I had used the majority of pro-level grinders on the market. These days, there are too many grinders, and few people can name half of the pro-level grinders available, let alone say they have used them.
Many grinders now offer adjustable RPM, which complicates making settings recommendations. When you increase RPM, much of the change in the particle size distribution is equivalent to turning the dial to a finer setting.
For example, “setting #5” at 400 RPM may behave like “setting #6” at 1500 RPM.
⸻
The Dose
Deeper coffee beds offer more flow resistance and require coarser grind settings than shallower beds.
For example, on an EK with settings 1–11, I might grind on #6 for a 15g V60, but #8 for a 22g V60.
In a no-bypass brewer, increasing bed depth may require a slightly greater coarsening of the grind than it would in a V60 or classic pourover.
⸻
Burr Geometry, Alignment, and Sharpness
It’s no longer enough to ask, “What setting would you use on an EK43?” There are many different burr sets available for that grinder and others.
If a burr set is truly “low fines,” one may need to grind a little finer than with a “core,” “HU,” or “all-purpose” burr set. One may also prefer the flavor of the coffee with a slightly faster flow through the coffee bed when using low-fines burrs.
If a burr set is poorly aligned, which is more common than is often discussed, the grounds will include more fines and more boulders. Generally, that will result in a faster flow rate at a given nominal setting on the grinder dial.
This is easy to observe when making espresso. I recommend using espresso flow rate as a guide to assessing burr alignment when installing new burrs on an EK.
Slower flow usually indicates better alignment.
⸻
Fines Production
The percentage of fines in the grounds has a massive effect on the flow rate of liquid through the coffee bed.
Beyond burr geometry, fines production is influenced by:
Roast level: darker roasts produce more fines.
Coffee origin: Ethiopians in particular often produce more fines.
Decaffeination: decaf coffees produce significantly more fines.
Bean temperature: colder beans produce more fines.
Many people believe processing method affects fines production, and sometimes it does a little.
But its effect is often overstated.
For example, posts claiming naturals produce more fines than washed coffees often fail to compare coffees roasted to the exact same ground color. In many cases, the naturals were simply darker.
⸻
Dialing In
The rule of thumb when dialing in is simple:
Begin at a coarser setting than you expect is required.
If the grind setting is too fine, clogging and channeling may occur, causing the coffee to taste astringent and unpleasant.
If the grind setting is a little too coarse, the coffee may be weaker or more acidic than desired, but it is usually still drinkable.
A second advantage of beginning too coarse is that the shorter brew time gives you a better sense of how much finer you should grind on the next attempt.
When the grind is too fine and the brew clogs or stalls, it can be much harder to estimate how much coarser you need to grind to find the optimal setting.
⸻
ST. DION Takeaway
A grind setting is not a fixed recipe number. It is a response to the coffee, the brewer, the dose, the grinder, and the desired flavor.
Start a little coarse, observe the flow, taste the result, and adjust with intention.
That is the difference between simply following a recipe and truly learning how to brew.
⸻
Originally written by Scott Rao here. Republished by ST. DION Coffee with permission.
our most popular articles
our most popular products
