BMI calculator
Body mass index compares weight with height. It is a screening indicator for populations, useful as a rough signal and poor as a verdict on one person.
- Category
- Overweight
- Weight range for 18.5–24.9
- 125.3 – 168.6 lb
- Distance from that range
- −1.4 lb
- Body surface area (Mosteller)
- 1.94
BMI is a population-level screening indicator, not a diagnosis. It does not apply to children, pregnancy, or highly muscular bodies. Talk to a clinician about what your figure means for you.
The formula
BMI = weight in kilograms ÷ (height in metres)². Imperial inputs are converted first: 1 lb = 0.45359237 kg, 1 in = 0.0254 m.
Worked example
77 kg at 175 cm: 77 ÷ 1.75² = 25.1, just into the overweight band, where the normal range would be 56.7 to 76.3 kg.
How to use it
- 1Measure height without shoes and weight at a consistent time of day.
- 2Switch the unit system rather than converting by hand.
- 3Read the range as a band, not a target: the cut-offs are statistical, not personal.
Questions people ask
Why is BMI criticised so much?
It cannot tell muscle from fat and ignores where fat sits. A muscular athlete and a sedentary person can share a BMI and have very different health profiles.
Are the cut-offs the same everywhere?
No. Some health authorities in Asia use lower thresholds, because cardiometabolic risk rises at a lower BMI in several Asian populations.
Last reviewed: 2026-10-20