Is there a standard measure for coffee grind size?

Question

There is a lot of measurement involved in brewing coffee: the weight of the grinds, temperature of the water, etc. But as far as I can tell, there is no standardization on the size of the grinds. Recipes usually call for hand wavvy sizes like "set the grinder midway between drip and espresso grind" (for an Aeropress). Even an approximate standard would be more useful.

I'm curious if there is a standard unit of measure for grind size? If there is, do grinder manufacturers use or publish this information?

Answer 1

Take a look at this link from Coffee Chemistry, it's not a standard, per se, but it provides useful information.

Table from article:

Answer 2

A quick search (surprisingly) revealed no standards for describing the grind. Neither the "International Coffee Organization" nor the "National Coffee Association USA" offer much more than: (from NCAUSA)

The Grind

If you purchase whole bean coffee, always grind your beans as close to the brew time as possible. A burr or mill grinder is preferable because all of the coffee is ground to a consistent size. A blade grinder is less preferable because some coffee will be ground more finely than the rest. If you normally grind your coffee at home with a blade grinder, try having it ground at the store with a burr grinder. You may be surprised at the difference!

An author at "About.com" does offer an rather functional definition, though it lacks the authority to be called a standard:

Coarse - Very distinct particles of coffee. Like heavy-grained kosher salt. Downright chunky.
Medium - Gritty, like coarse sand.
Fine - Smoother to the touch, a little finer than granular sugar or table salt.
Extra fine - Finer than sugar, but not quite powdered. Grains should still be discernable to the touch.
Turkish - Powdered, like flour. Most inexpensive (blade) grinders will be unable to grind this finely.

Answer 3

Microns! While there are variations in the application of descriptors like "Drip" and "Fine," the micron is definitely the universal unit of measurement, used by coffee grinder manufactures, for instance. For example, Ditting grinders have settings that correlate to 100's of microns, so that setting 5 creates grinds averaging 500 microns, etc. There is also a fairly new consumer product, the Kruve Sieve, that allows one to sift grinds using various micron-sized sieves, to determine the actually output of your grinder. (You may be surprised to see how much particle sizes vary with even the best grinders.) As for those descriptors, check out the following from coffeelabequipment.com: