Intermittent Fasting Calculator
Create custom fasting schedules (16/8, 18/6, 20/4) and estimate daily fasting and eating window times.
Input Parameters
Enter details for calculation.
Eating Window End
Expert Tip
Intermittent fasting does not change what you eat, but when you eat. Ensure you still hit your nutrient and calorie targets during your eating window.
Calculation Methodology & Details
Formula
Calculates the timeframe for both metabolic rest (fasting) and feeding phases based on a 24-hour cycle.
Important Disclaimer
The calculations provided are for educational and general informational purposes only. They do not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider.
How Intermittent Fasting Windows are Mapped
Follow these steps to use this calculator:
Select Protocol
Choose a ratio. 16/8 is the most popular starting point.
Set Start Time
Enter the hour (0-23) you wish to break your fast.
Related Calculators
View All Health Tools →Detailed Insights & Expert Guide
ℹ️ About this Calculation
This dietary and nutrition calculator helps optimize energy intake, macronutrient distribution, and dietary planning based on clinical metabolic guidelines and evidence-based nutrition science.
Variable Glossary
Dietary & Body Metrics
Calorie targets, macro ratios, body weight, activity level, or nutrient quantities consumed.
Metabolic Factors
Basal energy expenditure formulas (Mifflin-St Jeor, Harris-Benedict) and recommended daily allowances (RDA).
How to Calculate Step-by-Step
Step 1
Enter your personal stats, body weight, and physical activity multiplier.
Step 2
Select your health objective (maintenance, weight loss deficit, or muscle gain surplus).
Step 3
Get your tailored daily energy targets, macronutrient split, and nutrition guidelines.