Eating windows
Intermittent Fasting Calculator
Pick a fasting protocol, we recalculate calorie targets across your eating window.
Intermittent fasting compresses your eating into a shorter window. Calorie targets do not change, only meal timing. Common protocols: 16:8 (16-hour fast / 8-hour eating window), 18:6, 20:4, OMAD (one meal a day), 5:2 (two non-consecutive 500–600 kcal days per week), ADF (alternate-day fasting).
Your daily target
· cal/day
Enter your details and click Calculate
- BMR · cal/day at rest
- BMI ·
- Lean body mass · kg
Pick your goal
Macros at maintenance
30% protein · 40% carbs · 30% fat
Numbers are estimates. Eat at your target for 2 to 3 weeks, track weight, and adjust by ±100 cal/day if it does not match your real maintenance. See how accurate is TDEE?
Show advanced metrics 12 metrics · 7 formulas · 2D macro selector · life-stage
All metrics
Calculate above to populate the full metric table.
All 7 BMR formulas (side-by-side)
Mifflin–St Jeor · Harris–Benedict (revised) · Katch–McArdle · Cunningham · Average · Simple multiplier · Custom
TDEE across activity levels
See how much your TDEE changes between sedentary and athlete. Highlighted bar is your current selection.
Macros: 2D selector
Goal × carb-split matrix: Cut / Maintain / Bulk × Low / Moderate / High carb.
Life-stage adjustments
Luteal phase · Pregnancy (T1/T2/T3) · Breastfeeding · Perimenopause · PCOS
Common protocols
- 16:8, eat 12pm–8pm, fast 8pm–12pm. Easiest entry. Most evidence base.
- 18:6, eat 1pm–7pm. Slightly tighter. Good for fat-loss phases.
- 20:4 (Warrior), eat 4pm–8pm. Two meals, harder adherence.
- OMAD, one large meal per day. Effective for some, hard to hit protein.
- 5:2, eat normally 5 days, restrict to 500–600 kcal on 2 non-consecutive days.
- ADF, alternate full eating days with fast days (~25% TDEE).
Does fasting boost fat loss?
Per multiple meta-analyses, intermittent fasting works for fat loss because it reduces total calorie intake, not via a magic metabolic effect. Calorie deficit is the active mechanism. Fasting is a delivery vehicle that some people find easier to adhere to.