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BMI Calculator

Calculate your body mass index and find out your weight category and ideal healthy weight range

How to use the BMI Calculator

1

Choose your unit system

Select metric (kg/cm) or imperial (lbs/ft+in) depending on your preference.

2

Enter your weight and height

Enter your current weight and height accurately for a correct result.

3

Press Calculate

Your BMI value, weight category, and healthy weight range appear instantly.

4

Read the result

The colour scale shows where your BMI sits among the four WHO categories.

About the BMI Calculator

Body Mass Index (BMI) is a universally recognised screening measure calculated by dividing weight in kilograms by the square of height in metres (weight ÷ height²). The World Health Organization (WHO) has adopted this index as a standard tool for classifying weight status in adults: underweight below 18.5, normal weight 18.5–24.9, overweight 25–29.9, Class I obesity 30–34.9, Class II obesity 35–39.9, and severe obesity 40 and above. Doctors and healthcare providers worldwide use BMI as a starting point for assessing the risk of weight-related conditions such as type 2 diabetes, cardiovascular disease, and hypertension. The calculation is performed entirely in your browser without saving any data. Also try the Percentage Calculator for other quick calculations.

Despite its widespread use, BMI has important limitations worth understanding. It does not distinguish between fat mass, muscle mass, bone density, or body water. As a result, athletes with high muscle mass may be classified as overweight despite being in excellent health, while older adults who have lost muscle mass may appear in the normal range despite elevated body-fat levels. The index is also not directly applicable to children and teenagers, who require age- and sex-specific growth charts. For a more accurate and comprehensive health assessment, it is recommended to combine BMI with waist circumference measurement, a body-composition analysis, and a consultation with your doctor or a registered dietitian to develop a personalised health plan. It is worth noting that BMI thresholds were originally developed from studies conducted on European populations. Subsequent research has shown the standard cutoffs may not be perfectly calibrated for Arab and Asian populations — some Asian health guidelines recommend treating a BMI of 23 as the overweight threshold and 25 as the obesity threshold, rather than the global standards of 25 and 30, because metabolic risks appear at lower BMI values in these populations. For long-term healthy weight maintenance, research consistently points to two key pillars: a balanced diet rich in vegetables, lean protein, and wholegrains while limiting added sugars and ultra-processed foods, combined with at least 150 minutes of moderate physical activity per week. This tool is completely free to use and stores no medical data whatsoever.

Frequently Asked Questions about BMI

Divide your weight in kg by your height in metres squared. Example: 70 kg and 1.75 m → BMI = 70 ÷ (1.75²) = 22.9.
According to the WHO: below 18.5 is underweight, 18.5–24.9 is normal, 25–29.9 is overweight, and 30 or above is obese.
BMI is a general screening tool, not a precise medical measurement. It cannot distinguish fat from muscle, so athletes may have a high BMI without being overweight. Consult your doctor for a complete evaluation.
The calculator automatically shows your healthy weight range for your height when you press Calculate. The healthy range is the weight that gives a BMI between 18.5 and 24.9.
Yes, the BMI calculator is completely free and runs in your browser with no signup or data upload required.

Source: WHO classification (2004) — BMI = weight (kg) ÷ height² (m). Categories: <18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, ≥30 obese. Last verified: 26 May 2026. BMI is a general screening indicator, not a substitute for medical evaluation.