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BMI Calculator

Calculate your BMI from height and weight—metric (kg/cm) or imperial (lb/ft/in). Get your adult category, healthy weight range, and optional waist-to-height screening. BMI is a screening estimate for adults, not a medical diagnosis.

BMI is a screening tool for adults—not a diagnosis. Formulas follow WHO/CDC adult standards. Children need age- and sex-specific percentiles (CDC).

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By Muhammad Abdullah Rauf · Founder, EverydayTools.proUpdated 2026-09-06· Reviewed by EverydayTools Editorial Team

What is BMI?

BMI (Body Mass Index) estimates whether weight is in a typical range for height. Adults use fixed WHO cutoffs; children and teens need age- and sex-specific BMI-for-age percentiles instead.

**How to calculate BMI**

**WHO adult categories (international):** underweight <18.5, healthy 18.5–24.9, overweight 25–29.9, Obese Class I 30–34.9, Class II 35–39.9, Class III ≥40.

**Asia-Pacific mode (optional):** overweight from BMI 23; higher-risk bands from 27.5 (WHO expert consultation public-health action points). Choose this only when that guidance applies to you—discuss with a clinician.

**Limitations:** BMI does not measure body fat, muscle, or fat distribution. Optional waist and waist-to-height ratio (WHtR) add central-adiposity context. This tool is a screening estimate for adults—not a diagnosis.

  • Metric: BMI = weight (kg) ÷ height (m)²
  • US customary: BMI = 703 × weight (lb) ÷ height (in)²

Enter height and weight to see your BMI, adult category, and healthy weight range—screening only, not a medical diagnosis.

When to use this BMI calculator

Adults checking weight status

Quick adult BMI screen

Answer “what is my BMI?” from height and weight with clear category labels.

US customary users

BMI in pounds, feet, and inches

Use imperial inputs with the standard 703 multiplier—no manual conversion.

Metric users

BMI in kg and cm

Enter centimeters and kilograms for the WHO metric formula.

People comparing category standards

WHO vs Asia-Pacific cutoffs

Toggle Asia-Pacific mode when population-specific guidance uses BMI 23 / 27.5 action points.

Anyone under 18

Not for child/teen percentiles

Use CDC Child and Teen BMI tools—adult cutoffs on this page do not apply.

BMI Calculator examples

Metric — healthy range

Input

175 cm · 70 kg · WHO

Output

BMI 22.9 — Normal (18.5–24.9)

70 ÷ (1.75)² ≈ 22.9. Healthy weight for 175 cm ≈ 56.7–76.3 kg.

Imperial — just into overweight

Input

5 ft 10 in · 180 lb · WHO

Output

BMI 25.8 — Overweight (25.0–29.9)

703 × 180 ÷ 70² ≈ 25.8. Healthy weight at 5′10″ ≈ 129–174 lb.

Asia-Pacific interpretation

Input

170 cm · 68 kg · Asia-Pacific

Output

BMI 23.5 — Overweight (23–27.4 Asia-Pacific)

Same BMI is Normal on WHO international (18.5–24.9) but Overweight under Asia-Pacific action points.

Athlete caveat

Input

180 cm · 95 kg · low body fat

Output

BMI 29.3 — Overweight on WHO

BMI cannot separate muscle from fat. Pair with body fat % or waist when muscular.

Adult BMI categories (WHO international)

Standard adult screening bands used by CDC and most US references.

CategoryBMI range
UnderweightBelow 18.5
Normal (healthy weight)18.5 – 24.9
Overweight25.0 – 29.9
Obese Class I30.0 – 34.9
Obese Class II35.0 – 39.9
Obese Class III40 and above

Screening categories only—not a medical diagnosis.

WHO international vs Asia-Pacific mode

Same BMI formula; different category cutoffs when Asia-Pacific mode is selected.

CategoryWHO internationalAsia-Pacific mode
Underweight<18.5<18.5
Normal18.5–24.918.5–22.9
Overweight25–29.923–27.4
Obese Class I30–34.927.5–32.4
Obese Class II35–39.932.5–37.4
Obese Class III≥40≥37.5

Asia-Pacific bands follow WHO expert-consultation action-point style cutoffs (23 / 27.5 / 32.5 / 37.5). Not universal for every individual.

Example BMI — imperial (WHO)

Illustrative results; enter your own values above for a precise figure.

HeightWeightApprox. BMICategory
5′0″120 lb23.4Normal
5′5″150 lb25.0Overweight
5′10″180 lb25.8Overweight
6′0″200 lb27.1Overweight

Example BMI — metric (WHO)

Common metric checks; calculator rounds to one decimal.

HeightWeightApprox. BMICategory
160 cm55 kg21.5Normal
170 cm70 kg24.2Normal
175 cm80 kg26.1Overweight
180 cm90 kg27.8Overweight

BMI vs related EverydayTools

Keep keyword ownership clear—use the right tool for the question.

QuestionUse
What is my BMI / category?This BMI Calculator
Target weight from height formulasIdeal Weight Calculator
Body fat %Body Fat Calculator
Daily calories / BMRCalorie Calculator
Child BMI percentileCDC Child & Teen BMI (external)

BMI formula and categories

Adult BMI uses the Quetelet index. Categories follow WHO international cutoffs, or Asia-Pacific public-health action points when that mode is selected. Healthy weight range back-calculates the selected healthy BMI band at your height.

Formula

Metric: BMI = weight(kg) ÷ height(m)²
Imperial: BMI = 703 × weight(lb) ÷ height(in)²
Healthy weight (WHO): 18.5 × h² to 24.9 × h²
Healthy weight (Asia-Pacific mode): 18.5 × h² to 22.9 × h²

Assumptions

  • Inputs are for adults (18+); age under 18 triggers a pediatric warning only
  • Category standard matches the selected WHO or Asia-Pacific mode
  • Sex affects optional waist thresholds, not the BMI formula

Limitations

  • Not BMI-for-age / CDC child or teen percentiles
  • Does not measure body fat, diagnose disease, or replace clinical care
  • Asia-Pacific cutoffs are optional guidance—not universal for every person
  • Pregnancy: standard adult BMI categories are not appropriate for gestational weight interpretation

Best practices

Measure consistently

Same time of day, barefoot height, similar clothing weight.

Pair BMI with waist when possible

Central fat can elevate risk even when BMI is “normal.”

Common mistakes to avoid

Applying adult BMI cutoffs to children or teens

Use CDC/WHO BMI-for-age percentiles for under 18. Adult bands on this page are wrong for kids.

Treating BMI as a diagnosis or treatment plan

Use BMI as one screening input. Discuss results with a healthcare provider before medical decisions.

Mixing metric and imperial without the 703 factor

Use the unit toggle. Imperial BMI requires 703 × lb ÷ in².

Assuming Asia-Pacific cutoffs apply to everyone

Toggle Asia-Pacific only when that guidance is relevant; confirm with a clinician.

When this tool isn't the right choice

Child or teen BMI percentile

This tool does not compute CDC/WHO growth-chart percentiles.

Body fat percentage or lean mass

Use Body Fat or Lean Body Mass calculators—BMI is weight-for-height only.

Clinical diagnosis or medication eligibility

Not a clinical assessment, obesity diagnosis, or prescribing tool.

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Frequently asked questions

What is my BMI and how do I calculate it?

Enter your height and weight above. Metric: divide kg by height in meters squared. Imperial: multiply lb by 703, then divide by height in inches squared. The result is your BMI; adult categories map that number to underweight through Obese Class III.

What is a healthy BMI range for adults?

On WHO international cutoffs, a healthy (normal) BMI is 18.5–24.9. Asia-Pacific mode uses a narrower healthy band of 18.5–22.9. This calculator also shows the matching healthy weight range for your height.

How is BMI calculated in kg and cm?

Convert cm to meters (divide by 100), square height, then divide weight in kg by that value. Example: 70 kg at 175 cm → 70 ÷ 1.75² ≈ 22.9.

How is BMI calculated with pounds and inches?

BMI = 703 × weight(lb) ÷ height(in)². Example: 180 lb at 70 in (5′10″) → 703 × 180 ÷ 4900 ≈ 25.8. Enter feet and inches separately in this tool.

Is BMI calculated differently for men and women?

No. The BMI formula is the same. Optional waist thresholds differ by sex; women often have higher body fat than men at the same BMI. Categories here do not use separate male/female BMI cutoffs.

Does BMI change with age?

The adult formula does not change with age. Interpretation can. Children need percentiles. Some clinicians interpret older adults differently—discuss with a healthcare provider. Entering age under 18 only shows a warning; it does not switch to pediatric charts.

What are Asia-Pacific / Asian BMI thresholds?

WHO expert consultation described lower public-health action points for many Asian populations (notably overweight around BMI 23 and higher risk around 27.5). Select Asia-Pacific mode to apply those category bands and a healthy weight range of BMI 18.5–22.9. They are not automatic for every person—use clinical judgment.

Can children or teens use this BMI calculator?

Not for category interpretation. Under 18 requires BMI-for-age and sex percentiles (CDC Child and Teen BMI Calculator). Adult fixed cutoffs on this page do not apply to kids or teens.

Can I use BMI during pregnancy?

Standard adult BMI categories are not designed for pregnancy. Weight-gain targets depend on pre-pregnancy BMI and gestational week—follow obstetric guidance. This tool can warn if you mark pregnancy; it does not provide gestational targets.

What is waist-to-height ratio (WHtR)?

WHtR = waist ÷ height. Some guidelines flag values ≥0.5 as increased central adiposity even when BMI is normal. Enter an optional waist measurement to see WHtR alongside BMI.

Is BMI a diagnosis of obesity?

No. BMI is a screening classification. It does not diagnose disease, prescribe treatment, or replace labs, waist measures, or clinical assessment.

Is this BMI calculator private?

Core calculations run in your browser. Height and weight are not uploaded to EverydayTools servers for normal use. Optional local save uses device storage only.

What BMI is considered obese?

On WHO international cutoffs, BMI ≥30 is obesity, subdivided into Class I (30–34.9), Class II (35–39.9), and Class III (≥40). Asia-Pacific mode uses different higher-risk bands starting at 27.5.

How much should I weigh for my height?

A common healthy weight range uses BMI 18.5–24.9 (or 18.5–22.9 in Asia-Pacific mode) converted to kg or lb for your height. This calculator displays that range automatically.

BMI vs body fat percentage — which should I use?

BMI is a fast height–weight screen. Body fat % estimates composition. Athletes and older adults often need body fat or waist context beyond BMI alone—use the Body Fat Calculator when that is the question.

Privacy, accuracy, and trust

Privacy

BMI calculations run in your browser. Height and weight are not uploaded to EverydayTools servers for core use. Optional local save uses browser storage on your device.

Accuracy

Matches WHO/CDC adult BMI formulas for equivalent metric inputs. Imperial uses the standard 703 multiplier (±0.1–0.2 possible from rounding).

How this tool works

Client-side JavaScript only for core calculation—confirm in your browser Network tab if needed.

Verification guidance

Cross-check with the CDC Adult BMI Calculator or NHLBI tool using the same height and weight.

Limitations: Adult screening only. No child percentiles, no clinical diagnosis, no body-fat measurement. Asia-Pacific mode is optional guidance. Pregnancy uses a warning, not gestational targets.

General BMI screening estimate only—not medical advice, diagnosis, or treatment. Consult a healthcare provider for personal health decisions.

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Reviewed by EverydayTools Editorial Team on 2026-09-06.

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