Intermittent Fasting Timer

Intermittent fasting covers a handful of different eating schedules — 16:8, 18:6, 20:4, OMAD's 23:1, and the weekly 5:2 — and this timer supports all five without picking a favorite or making any promise about what following one will do for you. Choose a protocol, tell it when your current window started, and the countdown does the rest: it is a scheduling tool, the same category as a stopwatch or a kitchen timer, not a diet plan and not health advice.

For the four hourly protocols, the timer runs plain date math against the fasting-hours/eating-hours split you picked: it works out which phase you are in right now and how much time is left in it, updates that every second, and mirrors the remaining time into the browser tab title so you can see it without switching back to the page. The moment the phase actually flips from fasting to eating or back, a short two-tone beep generated live by your browser's audio engine marks the change — no audio files, no notification subscription. Your protocol choice and window-start time are saved to this browser's local storage, so refreshing the page or coming back later picks up exactly where the countdown left off.

5:2 works on a completely different axis: instead of an hourly split within a day, you eat normally five days a week and sharply cut calories on two non-consecutive days. A countdown clock doesn't mean anything for a schedule like that, so this mode replaces it with plain explanatory text and a simple day-of-week picker for the two days you've chosen — no invented hourly number pretending to be precise about something that isn't.

This is, deliberately, the least dramatic fasting tool you'll find: it tracks a schedule and nothing else. It does not claim intermittent fasting will help you lose weight, improve your metabolism, or produce any other health outcome, because a countdown timer has no way of knowing that and neither do we. It is not an appropriate approach for anyone with a history of disordered eating, for people managing diabetes or other conditions that depend on regular food or medication timing, or for anyone who is pregnant or breastfeeding — if any of that describes you, this is not the tool to build a fast around. Like every tool on this site, everything runs locally in your browser: no account, no upload, and nothing about your eating schedule ever leaves your device.