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Free intermittent fasting calorie calculator: enter your daily calorie target (from TDEE or a deficit), your eating window, and meal count. Get kcal per meal and kcal per eating hour for 16:8, 18:6, 20:4, 14:10, or OMAD-style plans—with real numbers, not vague “eat less” advice.
Last updated: May 25, 2026
Need fast vs eat hours only? IF window calculator
Use TDEE, or a deficit/surplus plan from your calorie or TDEE calculator.
Fast:eat labels show fasting hours : eating hours (24 h day).
Plan
≈ 1000 kcal per meal (2 meals) and ≈ 250 kcal per eating hour across 8 h (16:8 fast:eat), from 2000 kcal/day total.
Fasting window
16 h
Ratio (fast:eat)
16:8
kcal / meal
1000
kcal / eating hour
250
1000
Even split across 2 meals
250
16:8 · 16 h fast
2000
kcal/day unchanged by IF timing
Default — 16:8, 2,000 kcal, 2 meals
1000 kcal/meal · 250 kcal/h · 16:8
Fat loss — 1,800 kcal, 18:6, 2 meals
900 kcal/meal · 300 kcal/h · 18:6
Higher intake — 2,400 kcal, 16:8, 2 meals
1200 kcal/meal · 300 kcal/h · 16:8
OMAD-style — 2,000 kcal, 4 h, 1 meal
2000 kcal/meal · 500 kcal/h · 20:4
Aggressive cut — 1,500 kcal, 16:8, 2 meals
750 kcal/meal · 187.5 kcal/h · 16:8
14:10 — 2,200 kcal, 10 h, 3 meals
733 kcal/meal · 220 kcal/h · 14:10
| Schedule | Eat (h) | kcal / meal | kcal / eating h |
|---|---|---|---|
| 20:4 | 4 | 1000 | 500 |
| 18:6 | 6 | 1000 | 333.3 |
| 16:8 | 8 | 1000 | 250 |
| 14:10 | 10 | 1000 | 200 |
At 1,800 kcal/day, 16:8 → 900 kcal/meal; 18:6 → 900 kcal/meal (same per meal when meals = 2).
TDEE ≈ 2500 kcal · deficit 500 kcal → target 2000 kcal/day
16:8, 2 meals → 1000 kcal/meal (2000 ÷ 2 = 1000 kcal per meal)
2000 ÷ 8 h = 250 kcal per eating hour
Intermittent fasting changes when you eat, not the physics of calories. A 500 kcal/day deficit works the same in 16:8 or three meals across the day if protein and adherence match.
This tool answers: “Given my daily target, how big should each meal be in my window?” It does not add an automatic “IF metabolism bonus.”
Typical flow: TDEE calculator → subtract deficit (e.g. 500 kcal) → enter result here → macro calculator for protein grams.
kcal_per_meal = daily_kcal ÷ meals_in_window
kcal_per_eating_hour = daily_kcal ÷ eating_window_hours
fasting_hours ≈ 24 − eating_window_hours
Default: 2000 ÷ 2 = 1000 kcal per meal; 2000 ÷ 8 h = 250 kcal per eating hour.
Suggested hashtags: #IntermittentFasting #Nutrition #Calories #MealPlanning #Calculator