BMI Calculator

Body Mass Index compares your weight to your height to give a quick, standardized screening number — for example, someone weighing 70 kg at 175 cm (1.75 m) has a BMI of 70 ÷ 1.75² = 70 ÷ 3.0625 ≈ 22.9, which falls in the "Normal weight" range (18.5–24.9). The same 70 kg on someone 160 cm tall gives 70 ÷ 1.6² ≈ 27.3, in the "Overweight" range — the formula is entirely about the ratio between the two, not weight alone.

BMI was designed in the 1830s as a population-level statistical tool, not an individual diagnostic one, and it's worth knowing what it doesn't measure: it can't distinguish muscle mass from fat mass, so a muscular athlete can show a high BMI despite low body fat, and it doesn't account for age, sex, or where on the body weight is distributed — all of which matter for actual health risk.

Treat BMI as a starting point for a conversation, not a verdict — it's genuinely useful as a quick, free, standardized screening number, especially for tracking your own trend over time, but it shouldn't replace an actual health assessment. If your BMI falls outside the "normal" range, that's a reasonable prompt to talk to a doctor, not a diagnosis on its own — especially since factors like muscle mass, bone density, age, and overall body composition all affect what a healthy number looks like for a specific person.