If your lunch break starts at noon and you finish dinner at 8 PM, the two meals fit an eight-hour eating window. From dinner to lunch the next day is 16 hours. That gives you a 16:8 schedule if lunch is your first meal and dinner is your last.
Start with the two times you want to keep
Write down when you can take your first bite at work and when you usually finish eating at home. A family dinner that starts at 7 PM and ends at 8 PM uses 8 PM as its endpoint. Count from lunch to that endpoint to get your eating window. Subtract that number from 24 to get the overnight gap.
- 10 AM break, 8 PM finish. The meals span 10 hours. From 8 PM to 10 AM the next day is 14 hours, giving you 14:10.
- Noon break, 8 PM finish. The meals span eight hours. Four hours to midnight plus 12 hours to noon gives you 16:8.
- 2 PM break, 8 PM finish. The meals span six hours. The overnight gap is 18 hours, giving you 18:6.
What if lunch starts at 12:30?
With a 12:30 PM lunch and an 8 PM finish, your eating window lasts seven hours and 30 minutes. The overnight gap is 16 hours and 30 minutes. You can record those times as they are. To keep an eight-hour eating window starting at 12:30 PM, it would close at 8:30 PM.
Check the schedule from either meal
In the free intermittent fasting calculator, choose 16:8. Select “My first meal” and enter noon to see an 8 PM finish. Now select “The end of my last meal” and enter 8 PM. The next eating window opens at noon the following day.
If your break moves but dinner stays fixed, keep the 8 PM input and try a different plan. If both times are fixed and you just want the exact gap, enter them in the hours-between-meals calculator.