How does the APM test work?
Each prompt asks for one action: press the key shown (Q, W, E, R, A, S, D, F) or click the target that appears in the field. Do it and the next prompt comes at once. Any other key or click is a miss. Choose 30 or 60 seconds. On a phone, tap the key caps under the field instead of a keyboard.
How is APM calculated?
APM, actions per minute, is your right actions multiplied by 60 and divided by the seconds played. Misses aren't subtracted, but they don't add anything either, and your accuracy (right actions out of all actions) is shown beside it, with how many were keys and how many were clicks.
Where does APM come from?
From real-time strategy games, where players issue commands with the keyboard and mouse at the same time. StarCraft 2 counts APM automatically. A 2013 study of game replays from 3,360 StarCraft 2 players at seven levels, from novices to professionals (Thompson, Blair, Chen and Henrey, PLoS ONE), calls it a measure of cognitive-motor speed, and found that what separates players changes as they get better.
How is this different from the CPS test?
The CPS Test counts every click, so it measures raw clicking speed. Here only the action you were asked for counts, so it measures how fast you can read a prompt and do the right thing with both hands. Mashing raises a CPS score; here it only adds misses.
For aiming alone, try the Aim Trainer; for keys alone, the Typing Speed Test.
What can affect your APM?
Where your hands are, mostly. On a computer, keeping your left hand resting on Q W E R and A S D F and your right on the mouse saves the time of looking down. On a phone the key caps and the field share one screen, so every action is a tap with the same thumb or finger, which is slower than two hands. A held key counts once, so there is no gain in leaning on a key.
Is a higher APM always better?
On this test, yes, because every action counted was one you were asked for. In games it's less simple: the APM a game shows counts every command, including repeated clicks that do nothing, so a high number can hide a lot of spam. The 2013 StarCraft 2 study by Thompson and colleagues found that which skills separate players changes as they improve, so APM is one part of skill, not the whole of it.