Why a Grind Setting on One Grinder Means Nothing on Another

A recipe that says "grind at 15" or "20 clicks" is only telling you about the grinder its author owns. On any other grinder the number means something different, and often nothing at all. That is why the same recipe can taste great for one person and sour for the next.

This post explains why grind numbers don't carry between grinders, and introduces an open fix: one shared scale that any recipe, app or grinder can use.

Every grinder counts differently

Grinder makers don't share a numbering system. A few examples, from the makers' own documents:

• Fellow Ode Gen 2: Fellow describes "11 settings with 31 total steps". Owners count the marks between numbers, so "6.2" means the second mark after 6.
• Baratza Encore: settings run from 1, very fine, to 40, very coarse, according to Baratza's manual.
• 1Zpresso hand grinders: settings are clicks, and the burrs move a different distance per click on each model. 1Zpresso lists 0.0088 mm a click on the J-Max S, 0.0125 mm on the JX-Pro S and 0.02 mm on the K-Ultra. Twenty clicks moves the burrs more than twice as far on a K-Ultra as on a J-Max S.

So "15" on an Encore, "15" on an Ode and "15 clicks" on a 1Zpresso are three unrelated grinds. Even two grinders with the same scale can disagree, because burr shape and size change what a given position produces.

What people do instead

Most grind advice falls back on words: "medium-fine", "like table salt", "a bit coarser than espresso". Words carry across grinders, but they are too vague to repeat. Your medium-fine and a roaster's medium-fine can be several settings apart.

The other fallback is a lookup table for one or two popular grinders. That works if you own one of them. Otherwise you are guessing.

One scale for every grinder

BrewMark has been converting settings between grinders with a single shared scale: the BrewMark Grind Index, 0 to 100. It has five fixed points:

Each grinder is described by its own setting at those five points, and its curve runs between them. Where a maker publishes a brew-method chart, the curve is fitted to it; otherwise it is estimated by comparison with grinders that have one, and each grinder page says which.

A recipe can then name its grind once, as a point on the index, and anyone can read it off their own grinder. Here is a pour-over grind of 38 on six grinders:

Each of these is a starting point. Burr wear, the coffee and your taste all move the right answer, so taste the first cup and adjust: finer if it's sour, coarser if it's bitter.

Using a recipe you already have

Most recipes won't use the index yet. Two ways to bring one onto your grinder today:

• The recipe names the author's grinder and setting. Put both into the grind converter with your own grinder; it goes through the index for you.
• The recipe only says "medium-fine" or names a method. Start from the method's point on the index, such as the pour-over guide's 38, and read it off your grinder's page.

Either way, the first cup tells you which direction to move.

Making it open

A scale only helps if other people can use it. So BrewMark has written it down as an open specification, the BrewMark Protocol, and published it under the MIT licence. It has three parts:

1. The scale: the Grind Index above, with the exact rules for drawing a grinder's curve.
2. A recipe format: the Open Brew Profile, a recipe as JSON whose grind is a point on the index rather than a setting on one grinder.
3. A lookup: a free API that takes a point on the index and a grinder and returns the setting, written the way that grinder's dial prints it. AI assistants can call the same lookup.

That means a roaster can print one recipe on a bag, an app can store one recipe for all its users, and an assistant can answer "what do I set my grinder to?" for whatever grinder you own.

What it doesn't do yet

The index orders grinds from fine to coarse. It is not yet a particle size: index 40 means "filter medium on this grinder's curve", not a number of microns. Tying each point to measured particle sizes is the next version, and every number will keep saying how it's known.

The spec is a draft for comment. If a setting looks wrong for your grinder, send a correction. If you build something with it, the spec's GitHub page takes issues and suggestions.