BMI Calculator
Calculate Body Mass Index and find your weight category. This free online fitness & health calculator runs entirely in your browser — no signup, no data sent anywhere.
Inputs
Results
How It Works (Formula & Method)
This calculator takes Unit System, Weight (kg), Height (cm), Weight (lb), and Height (in) as input and computes BMI and Category. The math runs entirely in your browser the moment you change a value — nothing is sent to a server, and your inputs are never stored.
The formula used is the standard fitness & health calculation for this metric. For a full step-by-step derivation with the default values, see the Worked Example section below.
Worked Example
Scenario: a person 175 cm tall weighing 70 kg.
- Convert height to meters: 175 cm ÷ 100 = 1.75 m.
- Square the height: 1.75² = 3.0625 m².
- BMI = weight ÷ height² = 70 ÷ 3.0625 ≈ 22.9.
- 22.9 falls within the 18.5–24.9 range, so the category is Normal.
For an imperial example: a 154 lb person 68 inches tall has BMI = (154 ÷ 68²) × 703 ≈ 23.4 — also Normal.
About the BMI Calculator
BMI (Body Mass Index) is a simple weight-to-height ratio used to screen for weight-related health risks. It is not a measure of body fat or fitness, but is a useful population-level indicator.
Tips & Considerations
BMI under 18.5 is underweight, 18.5–24.9 normal, 25–29.9 overweight, and 30+ obese. Athletes with high muscle mass may register as overweight despite low body fat.
Frequently Asked Questions
What does the BMI Calculator compute?
The BMI Calculator takes 5 input values and returns 2 results. Calculate Body Mass Index and find your weight category.
Is my data sent to a server?
No. The BMI Calculator runs entirely in your browser using static JavaScript. Your inputs are never transmitted to CalculatorHive or any third party, and nothing is stored after you close the page.
Is this calculator free to use?
Yes. Every calculator on CalculatorHive is completely free. There is no signup, no paywall, and no usage limit. The site is supported by display advertising and affiliate partnerships, which are clearly labeled.
Can I rely on this result for medical decisions?
Results are estimates intended for educational use. Health calculations vary with individual factors that a single formula cannot capture. Always consult a qualified clinician for personal health decisions.
Reviewed against: CDC, NIH, and World Health Organization guidance. Results are estimates for educational use only — not medical advice. Consult a qualified clinician for personal health decisions.