Intermittent Fasting Window Calculator
Following 16:8, 18:6 or another intermittent fasting plan? Choose your protocol and enter when your fast starts — usually when your last meal ends — and this tool gives you the exact clock times your eating window opens and closes.
How to use
- Choose your fasting protocol.
- Enter the time your fast begins, usually when your last meal ends.
- Read when you can eat again and when the eating window closes.
- Plan your meals inside the window shown, so fasting and eating hours stay consistent each day.
Note
This is clock arithmetic only: eating window opens after the fasting hours and closes after the eating hours. Fasting is not suitable for everyone — including during pregnancy, for people with diabetes on medication, or with a history of eating disorders — without medical guidance. Estimate only — not medical advice.
Frequently Asked Questions (FAQ)
What does the intermittent fasting calculator do?
It takes your chosen protocol and the time your fast starts and shows the exact clock times for your eating window.
Which fasting protocols are supported?
12:12, 14:10, 16:8, 18:6, 20:4 and OMAD 23:1.
When does my fast start?
Your fast starts when your last meal ends. Enter that time and the tool counts your fasting hours from there.
Does it remind me when my eating window opens?
No. It only shows the clock times for your window, so set your own alarm if you need a reminder.