Grinding Before Brewing: How to Measure Coffee
A good chance that we've all been there. What does "Medium Fine" or "Coarse" mean? These meanings can change depending on who speaks them and what their definition is. How can we use such an imprecise form of grind measurement when working with tenths of a gram in ratios?
Well, it's a bit of a story of accessibility to technology. The Fine through Coarse grind reference is one of the last holdovers of imprecise coffee terms. It harkens back to a time when blade grinders were the mainstay, and we weren't all that concerned with how coffee was ground, merely that it was.
But wait, you say. Surely there's a better way to measure the size of coffee grounds that can be globally recognized?
Meet the micrometre. Micron, as it's commonly referred to, is a standard measurement of the metric system. It denotes one-millionth of a meter. The symbol to express microns is 'μm .' Since understanding the scale of new measurement is always challenging, here are some examples:
- A human red blood cell is ~5-10μm.
- The diameter of a human hair is between 20-180μm.
- A grain of sand is ~400μm.
Now that we have some context, how can we use this for coffee? Coffee grinds generally span 200-1400μm.
So, where does my brew method fit, and how can I calibrate to that setting? Right now, there are only a couple of grinders on the market that will grind in microns specifically. The Ditting company makes grinders that have their adjustment rooted in microns, and Eureka has just released a whole line of grinders that are supposed to adjust in microns should you choose. As for checking your grind size, this can be achieved using a scientific sieve set or, more affordably, a Kruve Sifter.
Now, as for where your brew method sits on the scale, here are some popular ones below. For a more in-depth look, check out the brew guide on Kruve's website!
- Espresso: 200-450μm
- Aeropress: 400-700μm
- Pour over or filter coffee: 600-1000μm
- French Press: 800-1200μm
Remember that these are ranges. If you fall outside a given range for your brew method, don't sweat it. As long as it tastes good, that's the aim of the game. At least, now, you can communicate with your local baristas or friends more concisely.
Soon, gone are the days of "Medium-fine ."