What Grind Size Should I Use?
For the best brewing experience: Use a medium-fine grind size, shake to level the bed of coffee grounds before pouring in the water, and pour the water slowly.
The best grind size to use with an AeroPress coffee maker is between drip grind and espresso grind. We call this a medium-fine grind size (#4 on the chart below). A medium-fine grind size prevents most dripthrough while not being too difficult to press through. If you use a grind size that is coarser than medium-fine, you may see a dripthrough rate that is up to 2x faster than you see with a medium-fine grind. If you use a fine grind size (#5 on the chart), you may find it more difficult to press.
Note: Even when using the optimal medium-fine grind, it is normal for a minor amount of liquid (about 2-3%) to drip through prior to stirring and pressing. If a lot of liquid runs through prematurely, remember to shake to level the grounds and pour the water slowly. If an excess amount still runs through prematurely, you need to use a finer grind of coffee.
GRIND SIZE on a scale of 1-5
1 - French press (coarse)
3 - Drip (medium)
4 - AeroPress (medium-fine)
5 - Espresso (fine)
The average bag of preground store-bought coffee is a medium grind size (#3 on the chart) that is optimized for drip coffee makers.
We recommend using a burr grinder instead of a blade grinder with AeroPress coffee makers. If you do use a blade grinder, we have found that it takes around 30 seconds of continuous grinding to achieve a medium-fine grind size with a blade grinder.
A good grinder will grind coffee into particles of uniform size. Very fine particles block the flow of water and make it difficult to press. The same blocking occurs if your grinder is dull because it produces particles of varying size and the fine particles will block the spaces between the larger particles.