Intermittent fasting calculator
Plan your intermittent fasting schedule with the 12:12, 14:10, 16:8, 18:6 or 20:4 protocols: see when your eating window opens and closes and track how long you've been fasting.
How to useIntermittent fasting schedule
The time is saved in this browser. Educational information: talk to a health professional before starting.
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Intermittent fasting calculator: what it is for
Choose the protocol (12:12, 14:10, 16:8, 18:6 or 20:4) and enter the time of your last meal: the tool shows when the eating window opens and closes, how long you've been fasting and a progress bar that updates itself. The time is saved in your own browser.
Everything is calculated in your browser: no health data is sent or stored on a server.
How to use
- Choose the fasting protocol.
- Enter your last meal or tap I just started.
- Track your fasting time and when your next meal is.
When to use it
- Planning 16:8 day to day.
- Knowing what time you can have lunch.
- Fitting your fasting schedule to your work routine.
Frequently asked questions
What do the numbers 16:8 mean?
The first number is the fasting time and the second is the window in which you eat, in hours. With 16:8, you go 16 hours without eating, for example from 8 pm to 12 pm, and have your meals in the following 8 hours.
What's allowed during the fast?
Generally water, and coffee and tea without sugar or milk. Drinks with calories break the fast. Always follow your dietitian's or doctor's advice.
Is intermittent fasting for everyone?
No. Pregnant or breastfeeding people, minors, people with diabetes on medication, with a history of eating disorders or with other health conditions should avoid it or only do it with professional supervision.
Is it really free?
Yes, 100% free. No sign-up, no subscription and no usage limits. All Tools123 tools are free and run right in your browser.