How to use the overweight calculator
- Choose Metric (cm, kg) or US units (ft, in, lb).
- Enter your height and weight.
- Optionally enter your waist, measured halfway between your lowest rib and the top of your hip bone, after a normal breath out.
- Read how far your weight is above the healthy range, your WHO weight class, and your waist-to-height ratio.
How it's calculated
The calculator uses two separate checks. The first is body mass index, compared with the World Health Organization's adult classes. The second is waist-to-height ratio, which looks at where weight is carried:
A BMI of 25 to 29.9 is overweight and 30 or more is obesity, split into classes I (30–34.9), II (35–39.9) and III (40 or more). The UK's NICE guidelines read the waist-to-height ratio like this: 0.4 to 0.49 means no increased health risk, 0.5 to 0.59 means increased risk, and 0.6 or more means high risk. Put simply: keep your waist to less than half your height.
Worked example
These are the calculator's defaults: 175 cm, 85 kg, and a waist of 94 cm.
- Height squared: 1.75 × 1.75 = 3.0625
- BMI: 85 ÷ 3.0625 = 27.8, in the overweight class (25–29.9)
- Top of the healthy range: 24.9 × 3.0625 = 76.26 kg
- Amount above it: 85 − 76.26 = 8.7 kg
- Waist-to-height ratio: 94 ÷ 175 = 0.54, in the "increased health risk" band
- A waist under 175 ÷ 2 = 87.5 cm would bring the ratio below 0.5
In US units, the defaults are 5 ft 9 in and 187 lb. That gives a BMI of 27.6 and 18.4 lb above the top of the healthy range (168.6 lb).
Why check your waist too?
BMI can't tell fat from muscle, and it says nothing about where fat sits. Fat stored around the organs in the abdomen is the type most closely linked to type 2 diabetes, high blood pressure and heart disease. Two people with the same BMI can carry very different amounts of it. That's why a waist measurement adds useful information:
| BMI says | Waist-to-height says | What it suggests |
|---|---|---|
| Healthy | Under 0.5 | Low risk on both measures |
| Healthy | 0.5 or more | Weight may be normal but carried centrally |
| Overweight | Under 0.5 | Possibly muscular, or fat carried on hips and thighs |
| Overweight or obese | 0.5 or more | Both measures point to higher risk |
NICE suggests using waist-to-height alongside BMI for adults with a BMI under 35. Above that, BMI alone already shows high risk.
Limits and next steps
Both checks are for adults. They don't apply to children, during pregnancy, or to people with conditions that cause fluid retention. Athletes with a lot of muscle can show as overweight while carrying little fat. Some health services use lower BMI cut-offs, such as 23 and 27.5, for people of South Asian, Chinese and some other backgrounds. If you're above the healthy range, the healthy weight calculator shows the full target range. A doctor can check your blood pressure, blood sugar and cholesterol and help you decide whether, and how, to change your weight.
Frequently asked questions
How much overweight is "obese"?
For adults, obesity starts at a BMI of 30. At 175 cm that's about 91.9 kg, or about 15.6 kg above the top of the healthy range. The calculator's table shows the weight for each class at your height.
Can I be overweight but healthy?
Some people with a BMI of 25 to 29.9 have normal blood pressure, blood sugar and cholesterol, especially if they are active and their waist is under half their height. But risk tends to rise over time, so it's worth regular checkups with your doctor.
Why is my waist-to-height ratio high when my BMI is normal?
Your weight may be carried around your middle rather than spread evenly. This pattern still carries a higher risk of diabetes and heart disease, even at a normal BMI. More activity and a better diet can shrink waist size even when weight barely changes.
How do I measure my waist correctly?
Find the bottom of your lowest rib and the top of your hip bone, and measure around your body halfway between them. Stand up straight, keep the tape level and snug, and read it after breathing out normally.
Related calculators
- BMI Calculator — Your body mass index, weight category and healthy weight range, in metric or US units.
- Healthy Weight Calculator — The healthy weight range for your height, where your weight sits, and how far you are from the range.
- Body Fat Calculator — Estimate your body fat percentage with the U.S. Navy tape method and compare it with a BMI-based estimate.
- Calorie Calculator — Daily calories to maintain your weight, plus gradual targets for losing or gaining, using the Mifflin-St Jeor equation.
Results are estimates for general information and are not medical advice. Talk to a doctor or other qualified professional about your health. See our disclaimer.