Set timer for 13 min. Start this online visual, fullscreen timer set for 13 minutes. Sound alarm notification is optional.
How to use 13 minutes timer
The timer will tell you when your 13 minutes has run out. It will keep counting upwards when time is up.
Sound notification (alarm) is optional. You can keep the timer running in the background if you for example open a new tab. If you have sound notification the timer will tell you when time is up.