Press Space to start and stop the timer.
Use ↑↓ to add and subtract minutes from the timer.
Press R to reset the timer.
Tap to start and stop the timer.
Swipe up and down to add and subtract minutes from the timer.
Tap and hold to reset the timer.
Presentation Timer also works with touch-only devices. Just visit this webpage.
Presentation Timer also works with non-touch devices. Just visit this webpage.