Enter your fasting and nutrition details
Use the planner below to calculate your eating window, fasting window, daily calorie estimate, hydration, and macro targets.
Example data table
This example shows how one completed entry translates into a fasting schedule, calorie estimate, and daily macro targets.
| Age | Sex | Weight | Height | Goal | Eating Window | Calories | Protein | Water |
|---|---|---|---|---|---|---|---|---|
| 30 | Female | 70 kg | 170 cm | Fat loss | 12:00 PM to 08:00 PM | 1,813 kcal | 140 g | 3.20 L |
| 38 | Male | 82 kg | 178 cm | Maintain | 11:00 AM to 07:00 PM | 2,725 kcal | 131 g | 3.37 L |
Formula used
Fasting schedule formulas
Eating window end = eating window start + 8 hours
Fasting window start = eating window end
Fasting window end = next eating window start
Meal spacing = 8 ÷ (meals - 1)
Nutrition formulas
BMR uses the Mifflin-St Jeor equation.
TDEE = BMR × activity factor.
Calorie target = TDEE × goal factor.
Protein = weight × protein factor.
Fat = weight × fat factor.
Carbs = remaining calories ÷ 4.
Water target is estimated as 35 milliliters per kilogram, plus 0.5 liters for every 30 workout minutes.
How to use this calculator
- Enter your age, sex, weight, and height.
- Select your activity level and nutrition goal.
- Choose when your eating window should begin.
- Add wake time, sleep time, meals, and workout details.
- Press Calculate fasting plan to show results above the form.
- Review your fasting window, calorie target, macros, hydration, and meal schedule.
- Download the result as CSV or PDF for tracking.
Important note
This planner provides educational estimates. It does not replace individualized medical advice, especially for pregnancy, diabetes, eating disorders, underweight status, or medication-dependent conditions.
FAQs
1. What does 16/8 fasting mean?
It means fasting for 16 hours and eating within an 8-hour daily window. Many people use it to simplify meal timing and support calorie control.
2. Does this calculator estimate calories too?
Yes. It estimates BMR, TDEE, and a calorie target based on your selected goal, then creates macro targets from that calorie estimate.
3. Can I change my eating window start time?
Yes. Enter any start time, and the calculator automatically places the 8-hour eating window and the 16-hour fasting period around it.
4. Why does schedule fit matter?
A better fit usually means your eating window matches waking hours and finishes before sleep, which can make fasting more comfortable and easier to sustain.
5. Are macro targets exact requirements?
No. They are structured estimates meant for planning. Food preferences, training needs, health status, and professional guidance may justify different macro ranges.
6. Does workout timing affect the result?
Yes. The calculator checks whether your workout happens inside or near the eating window, which helps you evaluate recovery and meal timing convenience.
7. Is water target personalized?
It is estimated from body weight and workout duration. Climate, sweat rate, and medical needs can raise or lower your actual hydration requirement.
8. Can beginners use this fasting planner?
Yes, though beginners may want to shift gradually toward 16 hours. A later breakfast or earlier dinner can ease the transition.