Body Mass Index (BMI) relates weight to height squared and is widely used as a screening metric for weight categories in adults. It is quick to compute and helps frame conversations about healthy ranges, though it does not measure body fat directly.
About BMI Calculator
Body Mass Index (BMI) relates weight to height squared and is widely used as a screening metric for weight categories in adults. It is quick to compute and helps frame conversations about healthy ranges, though it does not measure body fat directly.
Athletes with high muscle mass and older adults with low muscle may fall outside typical categories despite different health profiles. BMI is a population tool, not a diagnosis.
CalculatorCamp BMI calculator provides an estimate for educational purposes only. Consult a qualified clinician for personal health decisions.
How to use this tool
Enter height and weight in the units shown on the form. Select sex or age options if offered. Press Calculate to see BMI value and the corresponding category band.
Formula & methodology
This bmi calculator applies the standard relationship below. Intermediate values are kept at full precision; only the displayed result is rounded.
BMI = weight (kg) / height (m)^2 OR BMI = 703 x weight (lb) / height (in)^2
Worked example
Suppose you weigh 70 kg and are 175 cm tall. Convert height to metres (1.75 m) and square it: 1.75 × 1.75 = 3.0625. Divide weight by that value: 70 ÷ 3.0625 = 22.86. A BMI of 22.86 falls in the Normal weight band (18.5–24.9). The healthy weight range for that height is 18.5 × 3.0625 ≈ 56.7 kg up to 25 × 3.0625 ≈ 76.6 kg.
Tips for accurate results
Use consistent units—do not mix cm with pounds without converting.
BMI categories for children differ; adult tools may not apply to minors.
Track trends over time rather than a single reading.
Pair BMI with waist circumference and clinical labs when advised by a doctor.
Frequently asked questions
Is BMI accurate for everyone?
It is a rough screen; muscle, age, and ethnicity can affect interpretation.
Is this medical advice?
No. Results are estimates for information only, not diagnosis or treatment.
What is a healthy BMI range?
Many adult guidelines cite roughly 18.5–24.9 as normal; confirm with a clinician.
Free?
Yes.
Sources & references
The factors and formulas used by this tool follow these references:
Health and fitness results are estimates for general education and planning. They are not medical advice and do not replace an assessment by a doctor, registered dietitian, or other qualified professional.
Last reviewed: September 2026. Found an error? Tell us and we will correct it.
Further reading
Guides that explain the ideas behind this calculator.