This intermittent fasting calculator builds a daily fasting schedule. Choose a plan such as 16:8 or 18:6, enter the time of your last meal, and it shows when your fast ends, your eating window and suggested meal times.
Popular fasting schedules
| Plan | Fasting | Eating window | Example |
|---|---|---|---|
| 12:12 | 12 hours | 12 hours | Eat 8 AM – 8 PM |
| 14:10 | 14 hours | 10 hours | Eat 10 AM – 8 PM |
| 16:8 | 16 hours | 8 hours | Eat 12 PM – 8 PM |
| 18:6 | 18 hours | 6 hours | Eat 2 PM – 8 PM |
| 20:4 | 20 hours | 4 hours | Eat 4 PM – 8 PM |
| 23:1 (OMAD) | 23 hours | 1 hour | One meal at 7 PM |
Worked example
On a 16:8 plan with a last meal at 8 PM, the fast ends at 12 PM the next day and the eating window runs from 12 PM to 8 PM.
Tips for getting started
- Start with 12:12 or 14:10 and lengthen the fast gradually.
- Drink water, and plain tea or black coffee, during the fast.
- Eat balanced meals with protein, vegetables and whole grains in your window; fasting does not cancel out overeating.
- Choose a window that fits your work and family meals so you can keep it up.
Frequently asked questions
Does intermittent fasting help with weight loss?
It can, mainly by helping some people eat fewer calories. Studies generally find results similar to other calorie-reduced diets.
Can I drink coffee while fasting?
Black coffee, plain tea and water have almost no calories and are usually allowed. Milk, sugar and creamers break a strict fast.
Is 16:8 fasting safe?
For most healthy adults, yes. It is not advised during pregnancy or breastfeeding, for people with a history of eating disorders, under 18s, or people with diabetes on glucose-lowering medicines without medical advice.
Does sleep count as fasting?
Yes. Sleep hours count toward your fasting time, which is why most people put the fast overnight.
Related calculators
Sources
Last reviewed: October 2026. For information only; not medical advice. Talk to a doctor about any health concerns.