Espresso grind size: getting it right
Espresso lives and dies by grind size. Too coarse and the shot gushes and tastes sour; too fine and it chokes the machine and turns bitter. Here is how to find the window in between.
Start with a target
Aim for a double shot of about 36 g out from 18 g in, in roughly 28 seconds. If you are faster than that, grind finer; slower, grind coarser. Adjust one variable at a time.
We covered the science of extraction in our extraction deep-dive (internal link), and there is a great calculator at this external tool.