Fasting Window Timer
A free intermittent fasting countdown timer. Pick a plan, press start, and watch a live countdown ring with your current fasting stage, elapsed progress and exact end time — no signup needed.
Choose your plan
Plan: —
Started: —
Ends at: —
Eating window: —
Current stage: Not fasting
Press Start Fast to begin your countdown.
How to use
- Pick a fasting plan (16:8, 18:6, 20:4, 22:2 or OMAD 23:1).
- Set your start time — or leave it as now — then press Start Fast.
- Watch the countdown ring, the elapsed bar and the stage guide until your eating window opens.
- Your fast is saved in this browser, so refreshing the page keeps it running.
Fasting stages guide
- 0 to 4 hours — Fed state: your body is using energy from your last meal.
- 4 to 8 hours — Early fasting: blood sugar falls and the body starts switching fuel sources.
- 8 to 12 hours — Fat burn begins: stored fat starts being used as fuel.
- 12 to 16 hours — Ketosis: the body increasingly burns fat and ketones for energy.
- 16 to 24 hours — Autophagy: longer fasts trigger deeper cellular cleanup processes.
- 24 hours and more — Deep fast: only for experienced fasters; drink water and listen to your body.
This tool is for education only and is not medical advice. If you have a health condition, are pregnant, or take medication, talk to a doctor before fasting.
Frequently Asked Questions (FAQ)
What is the fasting window timer?
It is a free browser timer for intermittent fasting. Pick a plan such as 16:8 or 18:6, press start, and it counts down your fasting window with a live ring, progress bar and stage guide.
Does the timer keep running if I refresh the page?
Yes. Your start time is saved in your browser, so a refresh or reopened tab continues the same fast from where it was.
Which fasting plans are supported?
The timer supports 16:8, 18:6, 20:4, 22:2 and OMAD 23:1 plans, plus a custom start time of your choice.
What do the fasting stages mean?
The tool shows general stages of fasting: fed state in the first hours, early fasting, fat burn beginning, ketosis around 12 to 16 hours, and autophagy in longer fasts. It is for education only, not medical advice.