BMI calculator (body mass index)
Your body mass index, the recommended weight for your height and, if you like, your waist-to-height ratio. For women and men, no sign-up.
26.0
slightly above the recommended range
Recommended weight for 170 cm: 54–71 kg (BMI 18.5–24.9).
How we worked it out
- 75.0 kg ÷ (1.70 m × 1.70 m) = 26.0
- The formula is the same for women and men, and the adult ranges don't change with age.
- Lots of muscle? BMI can read higher than your body fat really is – check your waist instead.
Adult BMI ranges
| BMI | How it is described |
|---|---|
| below 18.5 | below the recommended range |
| 18.5–24.9 | within the recommended range |
| 25.0–29.9 | slightly above the recommended range |
| 30.0 and over | above the recommended range |
Ranges from the World Health Organization. We deliberately avoid the clinical labels: these are statistical ranges, not a description of a person.
What BMI doesn't show
- What your weight is made of. Muscle and fat look the same to BMI – so it often reads high for people who train.
- Where the fat sits. Fat around the middle matters more for health, so measuring your waist helps.
- Changes with age. Muscle drops with age even at the same weight – keeping strength and protein up matters.
- Pregnancy. BMI ranges don't apply during pregnancy or breastfeeding.
More in our guide BMI: what it shows and what it doesn't. You can also work out the recommended weight for your height, your body fat percentage and your calorie needs.
Frequently asked questions
How is BMI calculated (formula)?
BMI = weight in kilograms ÷ (height in metres × height in metres). For example, 78 kg and 1.65 m: 78 ÷ 2.72 ≈ 28.7.
What is a normal BMI?
For adults, 18.5–24.9 is the recommended range (World Health Organization ranges). These are statistical ranges, not a diagnosis or a judgement of a person.
Is the BMI calculator different for women and men?
No. For adults the formula and the ranges are the same for women and men. Waist-size thresholds do differ – you'll find them in the body fat calculator and our belly fat guide.
Does BMI change with age?
Adult BMI ranges don't change with age. For children and teenagers (under 18), growth charts for age and sex are used instead, so we don't show them a number – a family doctor or paediatrician is the right person to ask.
Is BMI accurate for muscular people?
Often not. Muscle is heavy, so a trained person's BMI can be high without extra body fat. Waist-to-height is more useful then: below 0.5 is considered a healthy range (NICE, 2025).