BMI Calculator

Calculate your body mass index and ideal weight in metric or imperial

Fill in your measurements to calculate your BMI

How to interpret your BMI?

BMI (Body Mass Index) is calculated with: BMI = weight (kg) / height² (m). Developed by Adolphe Quetelet in the 19th century, it is used by the WHO to classify weight categories in the general adult population.

WHO categories

BMI < 18.5: Underweight | 18.5 - 24.9: Normal weight | 25.0 - 29.9: Overweight | 30.0 - 34.9: Obesity class I | 35.0 - 39.9: Obesity class II | ≥ 40: Obesity class III (morbid). The healthy range is between 18.5 and 24.9.

BMI limitations

BMI does not distinguish between muscle mass and fat mass. A very muscular athlete may have a high BMI without being overweight. It does not account for fat distribution (abdominal vs peripheral) or age and sex differences. Consult a doctor for a complete assessment.

Why choose OmniTools?

OmniTools brings together 20+ carefully crafted online tools built by our team. Every tool is designed to be fast, accurate and usable without sign-up. We believe essential everyday utilities — calculators, converters, generators — should be freely available with a clean interface and no intrusive ads. Our commitment: your data never leaves your browser.

Our tools are used daily by students, real-estate professionals, developers, designers, travelers and curious minds. Each tool comes with detailed documentation, formulas, reference values and practical tips to help you get the most out of it. We regularly ship new tools and improvements based on community feedback.

Frequently asked questions

Is this tool really free?

Yes, OmniTools is completely free, with no sign-up and no usage limit. No credit card required.

Is my data sent to a server?

No. All calculations and conversions run in your browser. Your data stays private on your device.

Does it work on mobile?

Yes, the interface is fully responsive and optimized for smartphones, tablets and desktops.

How often is the tool updated?

We continuously improve our tools based on user feedback to guarantee accuracy and reliability.