Health & Fitness
BMI Calculator
Enter height and weight in metric or imperial units to see your BMI and its general category.
For example 175 for 1.75 m
Your BMI
22.9
General adult category: Healthy weight
Where this sits
Category
Healthy weight
Healthy range for this height
56.7 – 76.3 kg
BMI 18.5 to 24.9
Height used
175.0 cm
Weight used
70.0 kg
BMI is a general screening figure, not a medical diagnosis. It does not measure body fat and does not account for muscle mass, age, sex, ethnicity or pregnancy. Speak to a qualified health professional about your own health.
Free to use. No sign-up required.
How it works
Body mass index compares your weight against your height. It is a quick screening number, not a measurement of body composition.
The calculation is always done in metric. If you enter imperial units, pounds are converted to kilograms (1 lb = 0.45359237 kg) and feet and inches to centimetres (1 in = 2.54 cm) before the formula is applied.
The categories shown are the general adult ranges used by most health bodies. They apply to adults aged 20 and over and are not adjusted for age, sex, ethnicity, pregnancy or muscle mass.
Formula
BMI (metric)
weight (kg) ÷ height (m)²
Height in metres, so 175 cm becomes 1.75.
Healthy weight range
18.5 × height (m)² to 24.9 × height (m)²
Worked examples
70 kg at 175 cm → BMI 22.9
70 ÷ (1.75 × 1.75) = 22.86, which falls in the healthy weight range of 18.5 to 24.9.
154 lb at 5 ft 9 in → BMI 22.7
Converted to 69.85 kg and 175.26 cm, then 69.85 ÷ 1.7526² = 22.74.
95 kg at 175 cm → BMI 31.0
95 ÷ 3.0625 = 31.02, which sits in the obesity range of 30 and above.
Frequently asked questions
What are the BMI categories?
The general adult ranges are: below 18.5 underweight, 18.5 to 24.9 healthy weight, 25 to 29.9 overweight, and 30 or above obesity.
Is BMI accurate for everyone?
No. BMI does not distinguish muscle from fat, so athletes and very muscular people often read as overweight despite low body fat. It is also less reliable for older adults, children, pregnant people, and across different ethnic groups, where the healthy thresholds can differ.
Should I make health decisions based on this number?
No. BMI is a rough screening figure only. It cannot diagnose anything and says nothing about your individual health. Speak to a doctor or qualified health professional about your own situation.
Why does the calculator ask for centimetres rather than metres?
Centimetres are how most people know their height, and it avoids decimal mistakes. The conversion to metres happens automatically before the formula runs.