BMI Calculator

Runs entirely in your browser

Calculate your Body Mass Index in metric or imperial units, see your weight category on a visual scale, and find your healthy weight range. Everything is calculated directly in your browser.

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0 BMI
— Category
— Healthy Weight Range
Underweight Normal Overweight Obese
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How to use BMI Calculator

  1. Choose Metric or Imperial units.
  2. Enter your height and weight.
  3. Your BMI, weight category and healthy weight range update instantly, along with a visual scale showing where you fall.

Features

  • Works in metric (cm/kg) or imperial (ft, in/lb) units.
  • Shows your weight category — Underweight, Normal, Overweight or Obese.
  • Visual scale showing exactly where your BMI falls.
  • Healthy weight range for your entered height.
  • 100% client-side — your figures are never sent to a server.

Worked Example

Metric: Height 175 cm, weight 82 kg.

Height in metres = 1.75
BMI = 82 / (1.75 × 1.75) = 82 / 3.0625 ≈ 26.8
Category: Overweight (25–29.9)
Healthy weight range at 175 cm: 56.7 kg – 76.3 kg

Imperial: Height 5 ft 9 in (69 in), weight 160 lb.

BMI = 703 × 160 / (69 × 69) = 112480 / 4761 ≈ 23.6
Category: Normal weight (18.5–24.9)
Healthy weight range at 69 in: 125.3 lb – 168.7 lb

Limitations of BMI

  • BMI only uses height and weight — it can't distinguish muscle from fat, so a muscular, athletic person can land in the "Overweight" range without carrying excess body fat.
  • The standard adult thresholds (18.5, 25, 30) used here aren't designed for children, teenagers or pregnant women, who need age- or condition-specific charts instead.
  • The imperial formula (703 × weight ÷ height²) and the metric formula (weight ÷ height²) are mathematically equivalent once units are converted — the constant 703 exists purely to let you use pounds and inches directly.
  • The "healthy weight range" is simply the weight span that produces a BMI of 18.5–24.9 at your entered height — it's a mathematical range, not an individual recommendation from a medical professional.

Is BMI Calculator safe?

Yes. Whether you switch to imperial units — using the 703 constant to work directly with pounds and inches — or stay in metric, the BMI and healthy-weight-range formulas run locally in your browser, so your height and weight are never uploaded or sent to a server.

Frequently Asked Questions

How is BMI calculated?

BMI is calculated as weight in kilograms divided by height in metres squared. In imperial units, it's 703 × weight in pounds divided by height in inches squared.

What do the BMI categories mean?

Using the standard adult BMI ranges: below 18.5 is Underweight, 18.5–24.9 is Normal weight, 25–29.9 is Overweight, and 30 or above is Obese.

Is BMI accurate for everyone?

BMI is a general screening measure and doesn't account for muscle mass, bone density, age or sex. It may be less accurate for athletes, older adults, children, and pregnant women. Use it as a general guide, not a diagnosis.

How is the healthy weight range calculated?

It's the range of weights that would give you a BMI between 18.5 and 24.9 at your entered height.

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