16:8 fasting calculator
Enter when you finished eating. The calculator shows when your 16-hour fast ends and your 8-hour eating window.
Loading the calculator…
How a 16:8 schedule works
16:8 divides each day into 16 hours of fasting and an 8-hour eating window. Because part of the fast is spent asleep, the eating window usually sits in the middle of the day.
Finish dinner at 8:00 PM and the fast ends at noon; the eating window then runs from noon to 8:00 PM. Finish at 6:00 PM and the window is 10:00 AM to 6:00 PM. The window can be placed anywhere, as long as the fast before it is 16 hours.
Questions
What time can I eat on 16:8 if I stop eating at 8:00 PM?
A 16-hour fast from 8:00 PM ends at noon the next day, and the 8-hour eating window runs from noon to 8:00 PM. Enter your own time above to see your window.
What if I start later than planned?
In the tracker, each fast is timed from when you actually start it. Start a 16-hour fast an hour late and its end moves an hour later, while the rest of your schedule stays where it was.
What happens when the clocks change?
A fast is measured in real hours. On the night the clocks go back, a 16-hour fast that starts at 8:00 PM ends at 11:00 AM by the clock, not at noon. The calculator and the tracker both count real hours, and the calculator marks any fast that has a clock change inside it.
Is this medical advice?
No. The calculator does arithmetic on times. It knows nothing about your health and cannot tell you whether fasting, or a fast of this length, is suitable for you. Talk to a healthcare professional before you start, and read the safety information.