BMI Calculator
Calculate your Body Mass Index (BMI) and see your healthy weight range in metric or imperial units.
Reviewed October 7, 2026 Runs in your browser — inputs are never stored
This tool provides general educational estimates only and is not medical advice. It does not diagnose, treat, or replace guidance from a qualified healthcare provider. Consult a doctor for decisions about your health.
About the BMI Calculator
A BMI (Body Mass Index) calculator is a health screening tool that shows whether your weight is healthy for your height. BMI is widely used in healthcare, fitness, and wellness to flag potential risks associated with being underweight, normal weight, overweight, or obese. The calculator is useful for individuals monitoring their health, fitness enthusiasts tracking progress, healthcare providers assessing patients, and anyone who wants a quick, objective snapshot of their weight status. Enter your height and weight in metric or imperial units and it instantly returns your BMI value and corresponding category, plus the healthy weight range for your build. Understanding your BMI can motivate positive lifestyle changes, help identify health risks early, and set a baseline for fitness goals. While BMI does not distinguish muscle from fat and is not a perfect measure of body composition, it remains a valuable screening tool recommended by major health organisations for initial assessments. Always discuss your results with a qualified professional before making health or diet decisions.
How to use it
- 1Select metric (cm/kg) or imperial (ft/in/lb) units.
- 2Enter your height carefully — small errors change BMI a lot.
- 3Enter your current body weight.
- 4Calculate to see BMI value, category, and healthy weight range.
- 5Treat the result as a screening guide, not a diagnosis.
Worked example
175 cm and 70 kg → BMI ≈ 22.9, in the healthy range. The tool also shows the weight band that keeps BMI between 18.5 and 24.9 for that height. Athletes with high muscle mass may land “overweight” on BMI alone, so pair the number with waist, fitness, and clinical advice.
How it works
Formula
Metric: BMI = weight(kg) / height(m)²
Imperial: BMI = 703 × weight(lb) / height(in)²
Categories
- Under 18.5 — Underweight
- 18.5–24.9 — Healthy weight
- 25–29.9 — Overweight
- 30+ — Obesity
Who it is for
Adults monitoring their weight status, fitness enthusiasts tracking progress, healthcare providers doing quick screenings, and anyone who wants an objective snapshot of whether their weight is healthy for their height.
Why it helps
BMI is a fast, free screening measure that flags potential weight-related health risks before they become serious — it takes seconds and needs only height and weight.
Tips for better results
- Measure height without shoes and weight in light clothing, ideally at the same time of day each time you check.
- Use all metric (kg/cm) or all imperial (lb/in) units — mixing them is the most common source of wrong results.
- Track the trend over weeks rather than fixating on one number; BMI is most useful as a direction indicator.
- Pair BMI with waist circumference — two people with the same BMI can have very different health risk.
Common mistakes to avoid
- Mixing imperial and metric units in the same calculation (e.g. pounds with centimetres).
- Treating a single BMI value as a diagnosis — it ignores muscle mass, bone density, and body composition.
- Using adult BMI ranges for children, who need age- and sex-specific percentile charts instead.
- Entering last month’s weight instead of a current measurement, which hides real progress.
Frequently asked questions
A:Not always. BMI does not distinguish muscle from fat, so very muscular people may register as overweight.
A:A BMI between 18.5 and 24.9 is generally considered healthy for most adults.
A:The adult BMI ranges are the same regardless of age; children use age- and sex-specific percentiles instead.
Reviewed for accuracy · Last updated October 7, 2026
Formulas follow recognised clinical references — including WHO BMI classifications, the Mifflin-St Jeor equation, and Naegele’s rule — and are periodically checked against published reference values.
CalcWisee Editorial Team
Calculator development and formula review
CalcWisee is an independent site founded by Ayman. Every calculator is built from a published formula or official definition, tested against hand-worked examples before it goes live, and corrected promptly when a reader reports an issue to ayman@calcwisee.com.
Expertise: Financial mathematics, Health and fitness formulas, Applied mathematics, Unit conversion standards
References & sources
Related guides
Understanding BMI and a Healthy Weight Range
Learn how BMI is calculated, what each category means, a worked example, and the real limits of BMI as a health measure.
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