BMI Calculator
Body mass index from height and weight, with the healthy range for your height.
Your figures
Result
How to use this tool
- Enter your own figures over the defaults — Weight, Height.
- The answer updates as you type. There is no button, and nothing is sent anywhere.
- Change one input at a time to see how sensitive the answer is to it.
BMI was designed to describe populations, not individuals. It takes no account of muscle mass, bone density, body composition or fat distribution, so a muscular person can register as overweight while carrying very little fat.
How it works
This takes 2 inputs — weight, height — and returns bmi, category, healthy range for your height and note. The whole calculation happens in this page as you type: there is no submit button, no request, and nothing stored.
A worked example
Worked through with the figures the page already has in it: weight of 70 kg and height of 175 cm, giving bmi of 22.9. These numbers come from running the calculator’s own code, not from being typed in here, so they cannot drift away from what you see on screen.
Starting from:
- Weight: 70 kg
- Height: 175 cm
| Result | Value |
|---|---|
| BMI | 22.9 |
| Category | Healthy weight |
| Healthy range for your height | 56.7–76.3 kg |
| Note | BMI ignores muscle mass and body composition. It is a screening figure, not a diagnosis. |
BMI Calculator — frequently asked questions
What is a healthy BMI?
Conventionally 18.5 to 24.9. Below 18.5 is classed as underweight, 25 to 29.9 as overweight, and 30 and above as obese.
Is BMI accurate for athletes?
No. Muscle is denser than fat, so athletes routinely register as overweight or obese by BMI while having very low body fat.
Does BMI differ by ethnicity?
Health risk thresholds do. Several health bodies use lower cut-offs for people of South Asian descent, where metabolic risk rises at a lower BMI.
Is this calculator free?
Yes, with no account, no limits and no data collection. It runs entirely in your browser.
Should I rely on this for a financial or medical decision?
No. It is a planning estimate built on standard formulas and stated assumptions. For decisions that matter, speak to a qualified professional who can account for your full circumstances.
Is this calculator accurate?
The arithmetic is exact — it uses the standard formula. What limits accuracy is the assumptions: the figures you enter, and factors the formula does not model such as fees, taxes and rule changes.
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Nothing is sent anywhere. The figures you type stay in this page and are never transmitted or stored — how that works.
Disclaimer. The formula is exact; the answer is only as good as the figures and assumptions above. Not financial, tax, medical or legal advice. Full disclaimer.