Health & Fitness
Intermittent Fasting Calculator
Plan intermittent fasting windows and meals.
Formulas and edge cases are reviewed against authoritative references before publication. For methodology, editorial standards, or corrections, use the links below.
Frequently asked questions
Which IF protocol is best?
16:8 is most popular and sustainable. Start there and adjust based on results.
Can I drink during fasting?
Water, black coffee, and plain tea are fine. Anything with calories breaks the fast.
Will IF help me lose weight?
IF is a tool for calorie control, not magic. You still need a calorie deficit.
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About this tool
Inputs
- Protocol
- First Meal Time
- Daily Calories
- Number of Meals
Results
- Eating Window
- Fasting Period
- Calories per Meal
- Meal Schedule
- Meal
- No schedule
Getting the right answer starts with the right formula. The Intermittent Fasting Calculator handles the computation so you can focus on the decision. Start by filling in protocol, first meal time, daily calories and number of meals. Based on these values, the tool computes eating window, fasting period, calories per meal and other key metrics. Health metrics give you a snapshot of where you stand, but they are not a diagnosis. Body fat percentage formulas rely on skinfold measurements or circumference-based estimates, each with its own margin of error.
People frequently need to plan intermittent fasting windows and meals but lack a quick way to do it — this tool fills that gap. Measure consistently — same time of day, same conditions — for the most reliable comparisons. IF is a tool for calorie control, not magic. You still need a calorie deficit. Tracking health indicators over time reveals trends that one-off measurements miss. Run the calculation with your best-case and worst- case assumptions to bracket the likely outcome.