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BMI Calculator
Body Mass Index gives a quick estimation of your weight relative to your height. Together with your waist measurement you get a more complete picture — especially if you do strength training, because BMI alone does not account for muscle mass.
Limits for
How do I measure this?Your BMI
24.1
Healthy weight
This falls within the standard healthy margin.
Waist ÷ height
0.47
Healthy range
Waist in cm: 84 cm · Healthy
Both your BMI and your waist fall within the healthy range. Measure again from time to time to follow your trend.
Guidelines for adults aged 19 to 69, not a diagnosis. Not intended during pregnancy.
Note: BMI does not account for muscle mass. Strong athletes with high muscle mass often score higher without it being unhealthy.
How to measure your waist
A correct measurement matters more than the formula. Here is how to do it:
- 1Stand upright with your feet slightly apart and your belly relaxed. Do not pull your stomach in.
- 2Find the midpoint between your lowest rib and the top of your hip bone. You can feel the hip bone at the side of your hip.
- 3Place the tape horizontally around your waist at that height, on bare skin or over thin clothing. Snug, but without pressing in.
- 4Measure after a normal exhale and read the value where the tape meets. No tape measure? Use a piece of string and then hold it against a ruler.
Measure twice and take the average. Always do it at the same time, for example in the morning before breakfast.
Reading your result
You get two results: the ratio between your waist and your height, and your waist in centimeters. The first applies to everyone, the second has separate limits for men and women.
Waist ÷ height
| Ratio | Meaning |
|---|---|
| below 0.40 | Low, possibly too lean for your height |
| 0.40 – 0.49 | Healthy range |
| 0.50 – 0.59 | Increased risk |
| 0.60 or higher | Greatly increased risk |
Rule of thumb: keep your waist below half of your height.
Waist in cm (European limits)
| Result | Men | Women |
|---|---|---|
| Healthy | < 94 cm | < 80 cm |
| Increased | 94 – 102 cm | 80 – 88 cm |
| Greatly increased | ≥ 102 cm | ≥ 88 cm |
The limits apply to adults aged 19 to 69 and are a guideline, not a diagnosis.
Why two measurements?
BMI tells you how heavy you are for your height, but not where that weight sits. Your waist adds that information: fat around the belly is more strongly linked to cardiovascular disease and type 2 diabetes than fat elsewhere in the body.
Scientific background and sources
A large meta-analysis (Ashwell, Gunn & Gibson, 2012) found that the ratio of waist to height predicts cardiometabolic risk factors better than BMI or waist circumference alone.
Because your waist is divided by your height, the same limit applies to everyone. A review of studies (Browning et al., 2010) proposed 0.5 as a useful limit for men and women and for different populations.
The limits in centimeters (94 and 102 cm for men, 80 and 88 cm for women) go back to research by Lean et al. (1995) and also appear in the WHO report on waist circumference (2008).
Both measurements are a screening, not a diagnosis. They say nothing about your fitness, blood pressure or cholesterol. If your result is raised or you are unsure, your family doctor is the right next step.
Sources
- Ashwell M, Gunn P, Gibson S. Waist-to-height ratio is a better screening tool than waist circumference and BMI for adult cardiometabolic risk factors: systematic review and meta-analysis. Obesity Reviews. 2012;13(3):275–286.
- Browning LM, Hsieh SD, Ashwell M. A systematic review of waist-to-height ratio as a screening tool for the prediction of cardiovascular disease and diabetes: 0·5 could be a suitable global boundary value. Nutrition Research Reviews. 2010;23(2):247–269.
- Lean MEJ, Han TS, Morrison CE. Waist circumference as a measure for indicating need for weight management. BMJ. 1995;311:158–161.
- World Health Organization. Waist circumference and waist–hip ratio: report of a WHO expert consultation, Geneva, 8–11 December 2008.
- NICE. Overweight and obesity management (NG246). 2025.
Last updated: October 2026
How is BMI calculated?
The formula is your weight in kilograms divided by your height in meters squared:
BMI = weight (kg) ÷ height (m)²
An example: if you weigh 78 kg and are 1.80 m tall, your BMI is 78 ÷ (1.80 × 1.80) = 78 ÷ 3.24 = 24.1. This falls within the healthy range.
BMI table for adults
These are the categories defined by the World Health Organization (WHO). They apply to adults aged 18 and older.
| BMI | Category |
|---|---|
| below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy weight |
| 25 – 29.9 | Overweight |
| 30 or higher | Obesity |
Different limits apply to children and adolescents under 18, varying by age. If you have doubts about your weight, consult your family doctor.
What your BMI does and does not say
BMI compares your weight to your height, but does not distinguish between muscle and fat mass. Because of this, strength trainees sometimes score higher than expected without it being unhealthy.
Is BMI reliable for athletes?
Less so than for the average person. Muscular athletes may score as "overweight" while having a low body fat percentage. View BMI as a first indication, not a final verdict.
What is a healthy BMI?
According to the WHO, 18.5 to 24.9 is considered a healthy weight for most adults. Age, gender, and muscle mass also play a role.
Does BMI differ between men and women?
The formula and categories are the same, even though women naturally average a higher body fat percentage at the same BMI.
How often should I recalculate my BMI?
Once a month is enough to track trends — daily fluctuations mean very little.
Which is better: BMI or waist?
They complement each other. BMI is quick and used worldwide, but counts muscle mass. Your waist, or its ratio to your height, shows better where the weight sits. For athletes the combination is the most informative.
Who is this calculator not suitable for?
Not for children and teenagers under 18 (different limits), not during pregnancy, and with caution for people over 70 and very muscular athletes. If you have an eating disorder, or you are worried about your weight or eating behavior, talk to your family doctor rather than a calculator.
What can you do with your BMI?
Your BMI is a starting point. If you want to take action, these are the logical next steps.