Tapping instead of clicking
On a phone or tablet the CPS test works the same way it does on a computer, with taps in place of clicks. Press Start test, then tap inside the box. Your first tap starts a five second timer, and every tap after that is counted. The live display shows time left, taps so far and a running CPS figure, and at the end you get your score, a rating, the total and your best.
Hold the device steady. Resting it on a table works better than holding it in the air, because your other hand is not fighting to keep it still.
One finger or two
How many fingers you use changes the result more than almost anything else.
One finger. Usually the index finger, tapping straight down. It is the closest match to normal mouse clicking, and the easiest method to repeat the same way each time.
Two fingers. Index fingers from both hands, or index and middle from one, taking turns. Each finger only has to tap half as often, so the total often rises. It also takes some practice to keep the rhythm even.
Thumbs. Holding the phone in both hands and alternating thumbs is comfortable, and many people find it natural from texting.
Whatever you choose, use the same method every time.
Touch latency
Every touchscreen takes a little time to detect a tap and pass it to the browser. That delay varies between devices, so the same hand can score differently on two phones. A screen protector, a case that presses on the edges or a dirty screen can also make taps less reliable. If your score seems stuck, clean the screen and lift your finger fully between taps, so each tap starts and ends clearly.
Keep phone scores separate
Scores are saved in the browser you are using, so your phone history is already kept apart from your computer history. A tablet has its own history too. Keep it that way when you compare: phone against phone, one finger against one finger. Matching a two finger phone score against a one finger mouse score tells you nothing.
For the full guide to clicking techniques, see the CPS test. To measure pure tap speed in a single burst, try the CPS test 1 second.