Body Mass Index (BMI) is a person's weight in kilograms divided by the square of their height in meters. It's a screening tool for weight categories: underweight ( =30).

Is BMI accurate for everyone?

BMI is a population-level screening tool, not a diagnostic of body fat or health. It overestimates fat in muscular athletes and underestimates fat in older adults who've lost muscle. Always consult a doctor for individual health assessments.

What extra features does this tool have compared to others?

Extras: (1) Healthy weight range, (2) BMI Prime, (3) Body surface area (Mosteller), (4) Ponderal Index, (5) Basal Metabolic Rate (Mifflin-St Jeor), (6) Daily calorie needs (5 activity levels), (7) Weight loss/gain goal calculator, (8) BMI z-score for age 2-20 (approximation), (9) CSV export of weight scenarios, (10) Dark/light metric/imperial toggle, (11) Macro nutrient split suggestions, (12) Waist-to-height ratio estimator.

Calculators Runs in your browser

BMI Calculator

Calculate Body Mass Index (BMI) from height and weight in metric or imperial units. Get category (underweight / normal / overweight / obese), healthy weight range, and 10+ extras. 100% private.

100% Private Works Offline Instant

BMI Calculator

WHO + Asian cut-offs · CDC BMI-for-age · Mifflin-St Jeor · 100% client-side

Private — runs in your browser

Inputs

Height (cm)

Range 30–300 cm

Weight (kg)

Range 2–500 kg

Age (optional)

Enables BMR, TDEE, body fat, and CDC percentile (ages 2–20)

Sex (optional)

Affects BMR, body fat, and ideal weight

Waist cm (optional)

Enables waist-to-height and waist-to-hip ratios

Options

Cut-off set

Asian cut-offs use WHO WPR 2004 (≥23 / ≥27.5)

BMR formula

Mifflin recommended; Katch-McArdle needs body fat %

Macro split

Carb/protein/fat split for maintenance calories

Decimal precision

Number of decimal places in displayed numbers

Presets

Headline metrics

Your BMI

24.2

kg/m²

BMI scale

Using WHO universal cut-offs (≥25 overweight, ≥30 obese). Scale shows BMI 15–40; values above 40 are clipped at the right edge.

Health risk & weight target

Risk: Low risk for weight-related disease.

Cut-off source: WHO universal (1995) (WHO TRS 854 (1995); NIH 98-4083 (1998))

Weight delta to healthy range: Lose 16.5 kg to reach maximum healthy BMI (2 kg to reach the other bound).

Detailed metrics

BSA — Mosteller

1.8 m²

sqrt(h_cm × w_kg / 3600)

BSA — Du Bois

1.8 m²

0.007184 × h^0.725 × w^0.425

BSA — Haycock

1.8 m²

paediatric-accurate

Ponderal Index

14.2

kg/m³ — corpulence

Validation & hints

INPUT_RANGE: Height 170 cm and weight 70 kg are within valid ranges.

Limitations of BMI

Athletes: BMI overestimates body fat in muscular individuals (muscle is denser than fat).
Elderly: BMI underestimates body fat in older adults who have lost muscle mass.
Pregnant: BMI is not applicable during pregnancy.
Children (under 2): BMI-for-age is not defined; use weight-for-length charts instead.
Asian populations: WHO recommends lower cut-offs (≥23 / ≥27.5) — toggle "Asian" in Options.

BMI is a screening tool, not a diagnostic of body fat or health. Consult a doctor for individual assessment.

References

WHO TRS 854 (1995) — Physical status: use and interpretation of anthropometry. Adult BMI cut-offs.
WHO WPRO 2000 — Asia-Pacific Perspective: Redefining Obesity. Asian cut-offs (≥23 / ≥27.5).
WHO 2004 Lancet 363:157 — Appropriate BMI for Asian populations.
CDC 2000 Advance Data 314 — CDC Growth Charts: BMI-for-age LMS tables, ages 2–20.
CDC 2022 — About Adult BMI — limitations for athletes, elderly, pregnant, children.
NIH 98-4083 (1998) — Clinical Guidelines on Overweight and Obesity.
Mifflin MD et al, Am J Clin Nutr 51:241 (1990) — Mifflin-St Jeor BMR equation.
Harris JA, Benedict FG, Carnegie Inst (1919) — Original Harris-Benedict BMR equation.
Katch VL, McArdle WD (1975) — Katch-McArdle BMR (lean-body-mass based).
FAO/WHO/UNU 2001 — Human Energy Requirements — activity multipliers.
Mosteller RD, N Engl J Med 317:1098 (1987) — Simplified BSA formula.
Du Bois D, Du Bois EF, Arch Intern Med 17:863 (1916) — Du Bois BSA formula.
Haycock GB et al, J Pediatr 93:62 (1978) — Haycock BSA formula (paediatric-accurate).
Deurenberg P et al, Br J Nutr 65:105 (1991) — Body fat % estimation from BMI, age, sex.
Devine BJ, Drug Intell Clin Pharm 8:650 (1974) — Devine ideal body weight.
Robinson JD et al, Am J Hosp Pharm 40:1622 (1983) — Robinson ideal body weight.
Miller DR et al, Am J Hosp Pharm 40:1622 (1983) — Miller ideal body weight.
Hamwi GJ, Am Diabetes Assoc (1964) — Hamwi ideal body weight.
USDA 2020-2025 Dietary Guidelines for Americans — Macronutrient distribution ranges.
Wishnofsky M, Am J Clin Nutr 6:660 (1958) — 7700 kcal per kg of body fat (used in goal calculator).

Reproducibility receipt

tool: bmi-calculator · version: 100x.1.0 · timestamp: 2026-09-05T17:11:11.186Z · fingerprint: 04ed2b6f

The fingerprint is a non-cryptographic hash of the inputs and options — it does not reveal the actual values.

Privacy: all calculations run locally in your browser. Nothing is sent to any server. History, presets, and drafts are stored in localStorage on this device only. .

Calculate Body Mass Index (BMI) from height and weight in metric or imperial units. Get category (underweight / normal / overweight / obese), healthy weight range, and 10+ extras. 100% private. Everything runs locally in your browser — your data never leaves your device.

How to use

Enter your input in the tool above.
Adjust any options to your preference.
Use the Copy or Download buttons to save the result.
Everything happens locally — your data never leaves your browser.

All tools

BMI Calculator

BMI Calculator

Inputs

Options

Presets

Headline metrics

BMI scale

Health risk & weight target

Detailed metrics

Validation & hints

Limitations of BMI

References

Reproducibility receipt

BMI Calculator — Result

How to use

BMI Calculator

Inputs

Options

Presets

Headline metrics

BMI scale

Health risk & weight target

Detailed metrics

Validation & hints

Limitations of BMI

References

Reproducibility receipt

BMI Calculator — Result