Health

Intermittent Fasting Calculator

Plan your intermittent fasting schedule. Choose a protocol like 16:8 or OMAD, set your eating window start time, and see your exact fasting and eating windows.

Intermittent Fasting Calculator

Fasting Protocol

Eating Window Starts At

Method

How this calculator works

Eating window = start time to (start time + eating hours). Fasting window = eating end time to next day's eating start. All times are computed using modular 24-hour arithmetic.

Select your preferred fasting protocol from the dropdown (for example, 16:8).
Enter the time your eating window begins using the time picker.
The calculator adds the eating-window length to your start time to find when eating ends.
Your fasting window runs from the end of eating until your eating window starts again the next day.

Disclaimer: This calculator provides estimates for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for decisions affecting your health. Results depend on the accuracy of inputs provided.

FAQ

Frequently asked questions

What does 16:8 intermittent fasting mean?

16:8 means you fast for 16 hours each day and restrict all your eating to an 8-hour window. For example, eating between 12:00 PM and 8:00 PM, then fasting until noon the next day.

Which fasting protocol is best for beginners?

Beginners often start with 12:12 or 14:10, which are gentler and easier to sustain. As your body adapts, you can gradually extend the fasting window to 16:8 or beyond.

What is OMAD?

OMAD stands for One Meal A Day, a 23:1 protocol where you fast for 23 hours and consume all your daily calories within a single one-hour eating window.

Can I drink water during the fasting window?

Yes. Water, black coffee, and plain tea are generally considered acceptable during the fasting window because they contain negligible calories and do not significantly break the fast.

Does the eating window start time matter?

The best start time is the one you can maintain consistently. Some people prefer an earlier window that aligns with circadian rhythms, while others center it around dinner. Consistency matters more than the exact clock time.