Free tool

Intermittent Fasting Calculator

Plan your eating window and fasting hours for the protocol that fits your lifestyle. Covers the most popular time-restricted eating schedules: 16/8, 18/6, 20/4 and OMAD.

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What is intermittent fasting

Intermittent fasting (IF) isn't a diet in the traditional sense, it's an eating patternthat alternates periods of fasting with a defined eating window. It doesn't prescribe what to eat, just when to eat it.

During the fasting window the body taps into stored glycogen and shifts toward using fat for fuel. Many people also find that a condensed eating window makes it easier to keep calorie intake under control without obsessing over macros at every meal.

Keep expectations realistic: intermittent fasting only produces fat loss when your total intake lands in a calorie deficit. The real benefit is behavioral, it gives the day a predictable structure that's easier to stick to than calorie counting alone.

Popular intermittent fasting schedules

12/12 - Beginner

12 hours fasting, 12 hours eating. The easiest on-ramp. Example: last bite at 8:00 PM, first meal at 8:00 AM the next day.

16/8 - Most popular

16 hours fasting, 8 hours eating. The most studied time-restricted eating protocol. Example: break your fast at 12:00 PM, last meal at 8:00 PM.

18/6 - Intermediate

18 hours fasting, 6 hours eating. Fits 2-3 meals. Example: first meal at 1:00 PM, last meal at 7:00 PM.

20/4 (Warrior) / OMAD

20-23 hours fasting with 1-2 meals per day. Advanced schedules best saved for experienced fasters. Tough to pair with heavy training volume.

Frequently asked questions