How the fasting timer works
Understand elapsed time, saved sessions, and what happens when you close the browser.
This guide does not provide medical advice. Speak with a healthcare professional before changing your routine if you have a health condition, take medication, are pregnant or breastfeeding, are under 18, or have a history of disordered eating.
The timer records a start timestamp in this browser. While the page is open, the display updates every second. If you close the page and return later on the same device and browser, it calculates elapsed time from that saved timestamp. Clearing site data removes the record.
Start, finish, or discard
Choose a duration from 1 to 24 hours and press Start. The ring shows progress toward that chosen time. The timer keeps counting after it reaches the target until you finish or discard it. Finish saves the actual start and end times in History; Discard removes the active timer without adding a session.
Why might the clock look different?
The display counts actual elapsed hours. A daylight saving clock change can make the wall-clock end time appear one hour earlier or later than expected. The timer does not prescribe a duration or judge a session.
Your data
Sessions stay in local browser storage. They do not follow you to another device or a different browser. You can edit or delete a saved session in the History calendar.
Further reading
National Institute on Aging: fasting diets overview
NIDDK: intermittent fasting and diabetes