Intermittent Fasting Schedule Calculator
Pick a fasting protocol and a first-meal time to get your exact eating window and fasting window as clock times.
How it works
Eating hours = 24 − fasting hours · Window = first meal → first meal + eating hours · Fast = window close → next first meal
Intermittent fasting alternates a daily fasting window with an eating window; the protocol name (16:8, 18:6, OMAD 23:1) gives the two lengths. Once you choose when your first meal lands, the eating window and the fasting window are fully determined. This tool turns the protocol and your first-meal time into exact clock times so you know precisely when to start and stop eating.
Worked example
On 16:8 with a first meal at 12:00 noon, the eating window is 24 − 16 = 8 hours long, so you eat from 12:00 PM to 8:00 PM and then fast from 8:00 PM until noon the next day.
Frequently asked questions
Which fasting schedule is best for beginners?
12:12 or 14:10 are gentle starting points — you fast overnight and slightly delay breakfast. Many people progress to 16:8 once that feels comfortable. The best schedule is the one you can keep consistently.
Can I drink anything during the fasting window?
Water, plain black coffee and unsweetened tea are generally considered fine as they contain essentially no calories. Anything with calories — milk, sugar, juice — breaks the fast.
Does the meal timing matter?
Total daily intake matters most for weight. Some evidence suggests an earlier eating window may help blood-sugar control, but adherence and overall diet quality matter more than the exact clock times.
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Educational estimate only — not medical, dietary or fitness advice. Individual needs vary; consult a qualified clinician or registered dietitian before making health decisions.