How your typing speed is calculated
Words per minute is calculated using the standard definition of a word as five characters, including spaces. Your net WPM counts only correctly typed characters, so accuracy is built into the score rather than reported separately from it. Raw WPM counts everything you typed, and the gap between the two numbers tells you how much speed you are losing to errors.
What counts as a good score
The average adult types between 35 and 45 words per minute. Around 60 WPM is a comfortable professional standard, and sustained speeds above 90 WPM put you in roughly the top few percent of typists. Accuracy matters more than raw speed: typing at 70 WPM with 99% accuracy is faster in practice than 90 WPM with 90% accuracy, because every error costs you the time to notice and fix it.
Practising deliberately
Repeating a test you already find easy builds very little. Improvement comes from working slightly above your comfortable speed, keeping accuracy above 97%, and targeting the specific keys and transitions that slow you down. Short daily sessions of ten to fifteen minutes outperform occasional long ones.