The range of grind levels typically runs from extra-fine to extra-coarse. Which one you choose depends on your brewing method because their different approaches to brewing all require a different grind size.
French Press: This method involves immersion. All of the coffee will be saturated throughout the brew time, between three to five minutes. That means you want a larger grind so it isn’t over extracted.
AeroPress: A variety of grinds will work well, its unique design allows for versatility in brewing. Startwith a medium grind, somewhere between sea salt and table salt. This will allow you to brew for a couple minutes, and the plunging won’t be too difficult. If you use a fine grind, go for a short brew (less than a minute) With a medium-coarse to coarse grind, you can brew between three to five minutes.
Pour Over Coffee (Hario V60, Kalita Wave, Bee House): Medium-fine is the best to start with. If your coffee is too sour, you’re under extracted, which means you’ll want a finer grind. If it is too bitter, on the other hand, you should try a coarser grind.
Chemex: A medium-coarse grind allows the Chemex to keep your flow rate steady, which should give you a brew time of around three and a half to four and a half minutes. If it is faster than that, you should try a slightly finer grind. If it is slower, you might need to go just a bit more coarse.
Automatic Drip: A medium grind is best, for machines with cone-shaped filters, this usually means starting with a medium-fine grind. With a flat-bottomed filters, you might want to start with medium.
Cold Brew: As the brew method with the longest extraction time, an extra-coarse grind is best
Espresso: Since the brew time is relatively short, you want a fine grind to properly extract all those wonderful flavors from your coffee. If you find that it is on the bitter side, try a little more coarse the next brew.