Calculated on this device from the sun's position (about a minute of accuracy). Communities use different conventions and safety margins, so follow your mosque's, synagogue's or community's timetable where you have one.
Your fasts are kept only in this browser (local storage).
Fasting isn't right for everyone. If you're pregnant or breastfeeding, under 18, have diabetes or another medical condition, take medication, or have a history of eating disorders, talk to a doctor first. Stop if you feel unwell.
Pick a plan and press Start fast. The timer counts from the moment you started, so it stays right if you close the tab, lock your phone or come back tomorrow. If you forgot to press start, use Started earlier or Edit start. When you end a fast it goes into your history, marked as reaching its goal or ending early, and the eating window for your plan starts.
The first number is hours of fasting, the second the hours you eat in, out of 24. 16:8 is the most common starting point. OMAD (one meal a day) is roughly 23:1. 5:2 is weekly rather than daily: you eat normally five days and much less on two non-consecutive days, so here you tick off those days instead of running a timer. Custom takes any length from 1 to 168 hours.
Your streak is the number of days in a row on which you finished a fast that reached its goal. Ending early still counts in your history and averages, just not toward the streak. For 5:2 the streak is weeks in a row with at least two low-calorie days.
In this browser's local storage on this device, and nowhere else. There's no account and nothing is sent to a server. It doesn't sync between devices; export a JSON backup to move it or keep it safe. Clearing site data deletes it.
From your chosen place's coordinates with the standard NOAA solar equations, entirely on your device. Dawn depends on which angle of the sun below the horizon your tradition uses, and far north or south in summer the sun may never get that low, in which case no time is shown.