Intermittent Fasting Calculator & Timer
Pick a fasting protocol and your eating-window start time to see your exact eating and fasting windows — plus a live countdown timer so you always know how long until your next meal or fast.
Intermittent Fasting Calculator & Timer
Pick a fasting protocol and your eating-window start time to see your exact eating and fasting windows — plus a live countdown timer so you always know how long until your next meal or fast.
Educational only, not medical advice — and intermittent fasting isn’t for everyone. It’s not recommended during pregnancy or breastfeeding, under 18, with a history of disordered eating, or with diabetes or other conditions affected by meal timing. Check with a professional first.
Fasting now; you can eat at 12:00 PM.
Fast 16 hours, eat within an 8-hour window — the most popular protocol. Black coffee, tea, and water are fine during your fast.
This isn’t medical advice, and fasting isn’t for everyone. It’s not recommended if you’re pregnant or breastfeeding, under 18, have a history of disordered eating, or have diabetes or another condition affected by meal timing — check with a healthcare professional first.
This is an educational estimate, not medical advice. Consult a qualified professional.
Save & share your result
What is intermittent fasting?
Intermittent fasting (IF) is about when you eat, not just what. You alternate periods of eating and fasting — most commonly a daily window, like eating within 8 hours and fasting for 16 (that’s 16:8). The idea is to give your body an extended daily break from food.
This tool turns your chosen protocol and start time into clear windows and a live timer, so the schedule is effortless to follow.
The popular protocols
- 14:10 — fast 14 hours, eat within 10. A gentle, beginner-friendly start.
- 16:8 — fast 16, eat within 8. The most popular daily window.
- 18:6 and 20:4 — longer fasts with tighter eating windows.
- OMAD — one meal a day (a ~1-hour window).
- 5:2 — eat normally 5 days; eat lightly (~500/600 kcal) on 2 non-consecutive days.
What breaks a fast?
During your fasting window, water, black coffee, and plain tea are generally fine and won’t meaningfully break a fast. Anything with calories — milk, sugar, snacks — starts the eating window. When you’re eating, focus on balanced, protein-rich whole foods rather than cramming in junk; IF is a timing tool, not a license to overeat.
Frequently asked questions
What is the 16:8 fasting schedule?
You fast for 16 hours and eat all your food within an 8-hour window — for example eating between noon and 8 p.m. and fasting overnight until noon the next day.
Does this have a live fasting timer?
Yes — set your eating-window start and the tool shows a live countdown to either the end of your eating window or the end of your fast, updating every second.
Does coffee break a fast?
Black coffee, plain tea, and water are generally considered fine during a fast. Adding milk, sugar, or anything with calories breaks it.
Is intermittent fasting safe?
For many healthy adults it’s well tolerated, but it isn’t for everyone — including during pregnancy, with diabetes, or with a history of disordered eating. Check with a healthcare professional before starting.
Sources & references
Not medical advice. This result is an educational estimate from HealthyLifeStyles (Trusted Wellness), based on population formulas — not a diagnosis or treatment. Always consult a qualified healthcare professional about your health.
https://www.healthylifestyles.com/tools/intermittent-fasting-calculator