Intermittent fasting calculator
Choose a schedule from 12:12 to 20:4 and your last-meal time. This fasting calculator shows when your fast ends and your eating window, in your time zone.
Your 12:12 day
12 hfasting
- Fasting
- Eating
- Now
- Fast ends
- —
- Eating window
- —
Intermittent fasting schedule chart
Every common schedule for the same last meal (—). The eating window opens when the fast ends.
| Schedule | Eating window | Your 24 hours |
|---|---|---|
| 12:12 | — | |
| 14:10 | — | |
| 16:8 | — | |
| 18:6 | — | |
| 20:4 | — |
Questions about this tool
Is this a personal health recommendation?
No. These tools count time and share general education. They can’t tell whether fasting suits you, and longer is not better.
Which time zone does the calculator use?
Your device’s time zone. If the time you pick is later than now, it counts as yesterday. Hours are counted as elapsed time, so on a night when the clocks change the end time shifts by an hour.
Are my answers saved?
No. Everything runs in this browser; nothing is sent or stored. The countdown keeps its start time in the page address, so you can bookmark it. It doesn’t send notifications.