The number of keystrokes will be the amount of times you’ve touched a key on the keyboard. We calculate the efficiency as follows:
efficiency = (total entered characters – keys pressed) / total entered characters * 100 (%)
For example, if I managed to enter a total of 100 characters with 60 key strokes, it will report that SwiftKey made my typing 40% more efficient.
To improve your efficiency score, always use the predictions to choose words.