Pour-over coffee has increasingly become one of the most popular choices among home baristas. This brewing method is incredibly satisfying to do, is capable of producing coffee that highlights very distinct flavor notes, and gives you unparalleled hands-on control over extraction parameters.
However, as many beginning coffee enthusiasts quickly find, brewing a well-extracted pour-over is far harder than is often assumed. And one of the most pivotal and challenging parameters to get right is grind size.
Grind Size and Pour Over
Grind size is a crucial parameter for all pour-over coffee, whether V60, Kalita Wave, Chemex, or the Origami dripper. Pour-over coffee is typically brewed in a cone-shaped dripper that either has a single large or multiple small holes in the bottom of the cone. As such, the two factors which dictate the speed of extraction are grind size and pouring technique.
However, it is extremely hard, and in fact fallacious, to assign a single correct grind size for pour-over. Quite simply, it depends on the recipe you are using. Having made pour over for years and having gone to a wide range of specialty coffee cafes, I have experienced delicious pour-over brewed quickly (2-3 minutes) with a very coarse grind and brewed slowly (5-6 minutes) with a very fine grind. Both can taste superb if brewed correctly and alter the mouthfeel of the final drink.
However, in general, a medium grind size is the most common particle size used for pour-over. Most pour-over recipes use between a 1:15 and 1:17 coffee to water ratio and have a total brew time of 3-4 minutes. Consequently, these recipes usually require a medium-ish grind size.
There are two ways to measure if you have the correct grind size.
First Way to Evaluate Grind Size: Total Brew Time
The first is total brew time or how long the drawdown takes. Most pour-over recipes require a 3-3.5 minute drawdown. As such, you should time every brew. If you find your brew is finishing closer to the 4-5 minute mark, there is a good chance you are using a grind size that is too fine and needs to be coarser. Similarly, if total brew time is too quick, your grind size is likely too coarse and needs to be finer.
This really is a matter of experimentation and tweaking. It depends not only on the specific pour-over recipe but also on the given beans you happen to be using, what roast level, at what altitude they were grown, and what region they come from. For example, Ethiopian coffee typically produces a large number of fines which will play into total brew time.
Second Way to Evaluate Grind Size: Taste
The other fundamental way to measure correct grind size is through taste. The taste will give you an indication if your pour-over is under or over-extracted. So, in general, if your pour-over tastes overly acidic, sour, and lacking sweetness, then it is under-extracted, and you need a finer grind size. Similarly, if your brew tastes bitter, harsh, dry, or hollow, it is over-extracted and requires a coarser grind size. A well-extracted pour-over should typically taste ripe, sweet, complex and leave a pleasant aftertaste.
So for each bean you use, you need to tweak your grind size based on these two factors; drawdown time and taste. Each bean is slightly different and so will require some tweaking. In general, I tend to grind lighter roasts slightly finer and darker roasts more coarsely.
The other pivotal factor to realize in all of this is grind consistency. Especially with a large hole pour-over like the V60, your drawdown time and extraction reflect not only grind size but grind consistency. Typically, the worse the grinder, the more uneven the grind consistency it will produce. So cheaper grinders will tend to make far more fines and boulders (small and large coffee particles) than something like the Mahlkonig EK43 which many cafes will use.
This poor grind consistency results in some of the coffee particles being over-extracted and others being under-extracted, producing an unpleasant taste. So if your pour-over tastes less than desirable, it may be grind consistency rather than grind size that is the issue.
In general, our recommendation for pour-over would be, at least to start with, to stick with a single simple brewing recipe (like the one below) and play with it. Try different grind sizes and see how it affects time and taste. Try doing a fast pour vs. a slow pour. Do your best to perfect a single brewing recipe rather than constantly switching between the hundreds of recipes out there. And keep in mind that your best shot of making a better pour-over may not be changing grind size but changing grinder.