Intermittent Fasting Calculator
Fasting and eating window schedule.
Enter your values
ⓘ Live results
Results
- Eating window
- 12:00 – 20:00
- Fast begins
- 20:00
- Fast ends
- 12:00
- Hours fasting
- 16
- Hours eating
- 8
- Fasting hours per week
- 112
Quick answer
Intermittent fasting sets a daily eating window; 16:8 means 16 hours fasting and an 8 hour window.
How to use the Intermittent Fasting Calculator
- 1Choose the hour of your first meal.
- 2Pick a fasting plan.
- 3Read your daily eating window.
Worked example
Using the values the calculator loads with:
Inputs
- First meal hour (24h)12
- Plan16:8
Results
- Eating window12:00 – 20:00
- Fast begins20:00
- Fast ends12:00
- Hours fasting16
- Hours eating8
- Fasting hours per week112
Frequently asked questions
Does black coffee break a fast?
No — plain coffee, tea and water are fine.
Is 16:8 best?
It is the easiest to sustain; longer fasts offer diminishing returns for most people.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.