Waist-to-Height Ratio Calculator
Enter your waist and height to see your waist-to-height ratio. For adults.
- Your waist
- Half your height
- Difference
This is a general screening measure, not a diagnosis. It does not replace advice from a healthcare professional. Nothing you enter is stored or sent anywhere.
What your result means
Your waist-to-height ratio compares your waist measurement to your height. The NHS advises trying to keep your waist size to less than half your height, which is a ratio below 0.5. If your result is 0.5 or above, your waist is half your height or more.
This is a screening measure, not a diagnosis. It is most useful as one piece of context, alongside other information such as your BMI, your daily habits, and advice from a healthcare professional.
How to measure your waist
- Stand upright and relaxed, with your stomach unclenched.
- Find the point halfway between your lowest rib and the top of your hip bone.
- Wrap a soft tape measure around your bare waist at that point, keeping it level all the way around.
- Breathe out normally, then read the measurement. The tape should be snug but not pressing into your skin.
- Measure your height without shoes, and use the same units (cm or inches) for both numbers.
For a fair comparison over time, measure at the same time of day and take the measurement twice. Small differences in tape position can change the result. The NHS calculator also walks you through its own measuring steps, so you can compare them with the ones above.
Waist-to-height ratio vs. BMI
BMI uses only your weight and height. Waist-to-height ratio uses your waist and height, so it reflects where your body carries weight. The NIDDK explains that BMI does not directly measure body fat, and that where your body stores fat matters, especially around the abdomen.
| BMI | Waist-to-height ratio | |
|---|---|---|
| Uses | Weight and height | Waist and height |
| Tells you about | Weight relative to height | Waist size relative to height |
| Does not tell you | Where weight is carried, or how much is muscle and how much is fat | Your overall weight or body composition |
For example, the NIDDK notes that a very muscular person may have a high BMI without carrying much body fat, and that older adults tend to lose muscle and gain body fat as they age, even when their BMI does not change. Neither measure is complete, so they are most useful together.
Limitations and who should not use this tool
This calculator is a general educational tool. It cannot diagnose any condition. Following the NHS’s guidance for its own calculator, do not use it if:
- you are under 18 (if you are 5 to 17, use it only with a parent or carer, and under 5 it is not suitable)
- you are pregnant
- you have been diagnosed with an eating disorder, or think you may have one
- you have a growth disorder or another condition that affects your height
- your BMI is over 35 (adults)
Other things to keep in mind:
- Measurement errors matter. A tape in the wrong place or pulled too tight changes the result.
- A ratio does not measure body fat directly, so it is an estimate, not a precise value.
- It does not replace advice from a doctor, pharmacist or other qualified professional. If you are worried about your waist size or cannot use the calculator, contact your local pharmacist or doctor.
Frequently asked questions
What is waist-to-height ratio?
It is your waist circumference divided by your height, using the same units for both. A ratio of 0.5 means your waist is exactly half your height.
What is a good waist-to-height ratio?
The NHS advises trying to keep your waist size to less than half your height, which means a ratio below 0.5. It is a general guide, not a personal target.
How do I measure my waist correctly?
Measure around your bare waist, halfway between your lowest rib and the top of your hip bone, with the tape level and snug but not tight, after breathing out normally. See the steps above.
Is waist-to-height ratio better than BMI?
It measures something different. BMI does not directly measure body fat or show where fat is stored, while waist-to-height ratio reflects waist size relative to height. They are most useful side by side.
Who should not use this calculator?
Do not use it if you are pregnant, have an eating disorder or think you may have one, have a condition that affects your height, are under 5, or have an adult BMI over 35. People aged 5 to 17 should use it with a parent or carer. See the limitations section above.
Is this a medical test?
No. It is a general screening measure for education only and cannot diagnose any condition.
Does the calculator store my numbers?
No. The calculation runs in your browser. Nothing you enter is saved or sent anywhere.
Sources
- NHS: Calculate your waist-to-height ratio
- NIDDK, National Institutes of Health: Am I at a healthy weight?
Last reviewed: October 13, 2026.
This page provides general educational information and does not give medical advice. Talk to a qualified healthcare professional about your own health.