Intermittent Fasting Calculator

Plan your IF schedule for 16:8, 18:6, 20:4, or OMAD. See eating windows and meal timing.

By Konstantin Iakovlev · Updated April 2026 · Source: CDC

Fasting Protocol
cal

Eating Window

12:00 PM – 8:00 PM

8 hours

Fasting Window

8:00 PM – 12:00 PM

16 hours

Break Fast At

12:00 PM

Last Meal By

7:00 PM

Meals

3

Calories / Meal

667

Recommended Meal Times

Meal 112:00 PM
Meal 24:00 PM
Meal 38:00 PM

Hydration Reminder

During fasting hours, stay hydrated with water, black coffee, or unsweetened tea. Aim for at least 8 glasses of water throughout the day.

Intermittent fasting may not be suitable for everyone, including pregnant or breastfeeding women, people with eating disorders, or those with certain medical conditions. Consult your doctor before starting.

Use the Intermittent Fasting Calculator above to calculate your results. Enter your values and see instant results — all calculations run in your browser.

Disclaimer: This calculator is for informational purposes only and does not constitute tax, financial, or legal advice. Results are estimates based on the information you provide and current rates. Always consult a qualified tax professional or financial advisor for advice specific to your situation.

How It Works

Mapping out exact fasting and eating windows takes the guesswork out of protocols like 16:8, 18:6, 20:4, and OMAD (One Meal A Day). As metabolic health draws more attention in 2026, dialing in a fasting schedule that fits your day can shape your energy, weight management, and broader sense of well-being. Pick a style and you get clear start and end times for both your fasting and eating periods.

The logic is direct. Feed it your chosen protocol, say 16:8, which means 16 hours of fasting paired with 8 hours of eating, along with the time you'd like to begin eating, and it returns the exact close of your eating window plus the precise start and end of your fast. OMAD works a little differently, carving out a concentrated one-hour eating period inside a 24-hour cycle and leaving the other 23 hours for fasting.

Regularity does most of the work here; the occasional off day won't derail you, but steady repetition is what delivers the benefits. Hydration tends to be the first thing people neglect during a fast, and skimping on fluids invites fatigue and headaches. Make the meals in your eating window nutrient-dense as well, since poorly managed calorie restriction can leave gaps in your nutrition.

Example: Planning a 16:8 Fasting Schedule

  1. 1 Input: You decide to follow a 16:8 intermittent fasting protocol and want your eating window to start at 12:00 PM (noon).
  2. 2 Calculation: The calculator determines that an 8-hour eating window starting at 12:00 PM will end at 8:00 PM. This means your fasting window will begin at 8:00 PM and conclude at 12:00 PM the following day (a 16-hour fast).
  3. 3 Result: Your personalized IF schedule is: Eating Window: 12:00 PM - 8:00 PM. Fasting Window: 8:00 PM - 12:00 PM (the next day).
  4. 4 Context: This schedule allows for two main meals and perhaps a snack within your 8-hour eating window, giving your body a prolonged period for metabolic repair and fat burning during the 16-hour fast. This is a popular choice for beginners due to its manageable fasting duration.

Source: CDC · Last updated: April 2026

Frequently Asked Questions

What is the best intermittent fasting schedule for beginners?
The 16:8 method (16 hours fasting, 8 hours eating) is the most popular and sustainable for beginners. Typically, you skip breakfast and eat from noon to 8 PM. You can drink water, black coffee, and plain tea during the fasting window.
Does intermittent fasting help with weight loss?
IF can be effective for weight loss primarily because it naturally reduces calorie intake by limiting eating hours. Studies show similar weight loss results compared to traditional calorie restriction. The best approach is whichever method you can sustain long-term.
Can I exercise while intermittent fasting?
Yes. Light to moderate exercise (walking, yoga, light weights) is fine while fasted. For intense workouts, consider scheduling them near the end of your fasting window or during your eating window. Stay hydrated and listen to your body.

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