# BMI Calculator

> bmi calculator that computes body mass index from height and weight, with healthy ranges by age for men and women. Free, private, runs locally in your browser.

- **Canonical URL:** https://boringtoolskit.com/bmi-calc/
- **Category:** Health
- **Evidence level:** authored-methodology
- **Reviewed:** July 26, 2026
- **Last verified:** 2026-09-21
- **Privacy:** Inputs and results stay in this browser unless the page clearly labels an external request.

## How it works

BMI = 703 x weight (lb) / height (in)^2.

## Worked example

170 lb at 5 ft 9 in: BMI 25.1, in the overweight band (25 to 29.9). Normal is 18.5 to 24.9.

## Assumptions

- Adult BMI ranges do not directly apply to children, pregnancy, athletes, or some medical contexts.
- BMI does not measure muscle, fat distribution, ethnicity-specific risk, or clinical history.
- Use this as a screening estimate and discuss health decisions with a qualified clinician.

## Common questions

### Is BMI a diagnosis?

No. BMI is a screening estimate. It can miss individual health context and body composition.

### Who should be careful using BMI?

Children, pregnant people, athletes, and people with medical conditions should use clinical guidance rather than BMI alone.

### Why does this adult BMI tool ask only for weight and height?

Adult BMI is calculated from weight relative to height. Age, sex, body composition, pregnancy, medical history, and population-specific risk still matter when interpreting the screening result.

## Related tools

- /body-fat-calculator/
- /calorie-calc/
- /calculators/health/

## Sources

- [Adult BMI categories](https://www.cdc.gov/bmi/adult-calculator/bmi-categories.html)
- [Health information](https://www.nih.gov/health-information)

---

*Local planning estimate. Verify current terms, rates, and policies before acting.*