Body composition

BMI Calculator

BMI = weight (kg) ÷ height² (m). Returns your value and the WHO weight classification.

Body Mass Index is your weight in kilograms divided by the square of your height in meters. The WHO classifies BMI under 18.5 as underweight, 18.5–24.9 normal, 25–29.9 overweight, 30+ obese (with three sub-classes).

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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

Advanced metrics

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

WHO BMI classifications

  • Underweight: < 18.5
  • Normal weight: 18.5–24.9
  • Overweight: 25.0–29.9
  • Obese class I: 30.0–34.9
  • Obese class II: 35.0–39.9
  • Obese class III: ≥ 40

BMI is a population-level screening tool. For individual body composition, pair it with waist-to-height ratio or body fat percentage.

Frequently asked questions

Is BMI accurate for athletes?
BMI cannot distinguish muscle from fat. Muscular individuals routinely register as "overweight" or "obese" by BMI while having low body fat. Pair BMI with body fat percentage or waist-to-height ratio for a fuller picture.
Does BMI differ for men and women?
No, the WHO classifications are the same for both. Body fat percentage thresholds differ by sex (women carry more essential fat), but BMI does not.
What about children and older adults?
Children use BMI-for-age percentile charts instead of fixed cutoffs. Older adults (65+) have evidence supporting slightly higher healthy BMI ranges, often 23–30.