TempoLife › Calculators › Intermittent Fasting Calculator
Intermittent Fasting Calculator
Intermittent fasting splits your day into an eating window and a fasting window. Pick a plan and your first meal time to see your exact schedule.
Free · no signup · updated August 2026
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How the fasting windows work
Intermittent fasting divides your 24 hours into an eating window and a fasting window. You pick the ratio; the clock time is up to you. Common plans:
| Plan | Fast | Eat | Best for |
|---|---|---|---|
| 14:10 | 14 h | 10 h | Beginners |
| 16:8 | 16 h | 8 h | The popular default |
| 18:6 | 18 h | 6 h | Steady fat loss |
| 20:4 | 20 h | 4 h | Experienced (Warrior) |
| OMAD | 23 h | 1 h | One meal a day |
Most people put the eating window over the middle of the day so the long fast covers the night. Fasting is a schedule, not a diet — what and how much you eat inside the window still decides your results, so pair it with the TDEE and macro calculators. Water, black coffee and plain tea are generally fine during the fast.
Frequently asked questions
What does 16:8 fasting mean?
16:8 means you fast for 16 hours and eat within an 8-hour window each day — for example eating between 12:00 and 20:00, then fasting until noon the next day. It is the most popular intermittent-fasting schedule because it fits around sleep.
When should I start my eating window?
Whenever suits your life — the window matters more than the clock time. Many people put the window over the middle of the day (a late breakfast to an early dinner) so the fast covers the night and finishes eating before bed.
Which fasting plan is best for beginners?
Start gentle: 14:10 or 16:8 are the easiest to sustain. Tighter windows like 20:4 or OMAD (one meal a day) fast longer and take practice — build up rather than jumping straight in.
Can I drink anything during the fast?
Water, black coffee and plain tea are generally fine and help with hunger. Anything with calories — milk, sugar, juice — breaks the fast. This tool schedules the window; what you drink is up to you.
More calculators
Estimates for general information only, not medical advice. BMR/TDEE use the Mifflin-St Jeor equation; individual needs vary.
