The formulas
Gross WPM = (characters typed ÷ 5) ÷ minutes. Net WPM = gross WPM − (uncorrected errors ÷ minutes). Accuracy = correct characters ÷ characters typed. A “word” is 5 characters, including spaces.
Worked example
1,250 characters in 5 minutes is 250 “words”, so gross is 50 WPM. With 4 uncorrected errors, net is 50 − 4/5 = 49.2, about 49 WPM. On a 1-minute test the same 4 errors would cost 4 WPM, so short tests punish errors harder.
Net vs gross on a job test
Employers usually care about net, because errors have to be fixed later. Some tests count an error per wrong word, others per wrong keystroke. Ask which, then practice on the job typing test, which scores net WPM automatically.