Waist-to-Height Ratio Calculator
Your waist measurement on its own says very little. Divided by your height, it becomes the figure national guidance actually screens with — and it takes thirty seconds and a tape measure.
Nothing you type here leaves your browser. A saved measurement is stored on this device only, and clearing it removes it.
Measure your waist in the right place
Most people measure where their trousers sit, which is not the same place and gives a smaller number.
Find the bottom of your ribs and the top of your hips. The point you want is midway between them, which for most people is above the navel rather than at it. Measure against bare skin or a thin layer, standing, after breathing out normally. Do not pull the tape tight, and do not hold your stomach in.
Take it twice. If the two readings disagree by more than a centimetre, take a third.
What the number means
The NHS states the rule in one line: keep your waist to less than half your height — a ratio under 0.5. The practical version needs no arithmetic at all. Take a piece of string the length of your height, fold it in half, and see whether it goes around your waist.
NICE, which sets clinical guidance in England, puts bands around it:
| Ratio | Band | On this measure |
|---|---|---|
| 0.4 – 0.49 | Healthy central adiposity | No increased risk on this measure |
| 0.5 – 0.59 | Increased central adiposity | Increased risk |
| 0.6 and above | High central adiposity | Further increased risk |
Those bands start at 0.4. A ratio below that is not described by them, and this page does not invent a meaning for it.
Note the word association. A waist-to-height ratio is a screening indicator, not a diagnosis. A high ratio does not mean you have anything — it means the odds across a population are worse, which is a reason to talk to someone qualified rather than a reason to panic.
Why height, and not a fixed waist size
A 90 cm waist means something different on someone 1.60 m tall than on someone 1.90 m. Dividing by height is what lets one threshold work across body sizes, and it is why this measure has largely replaced the older fixed waist cut-offs in guidance.
Who this is not for
The NHS says its waist-to-height calculator should not be used by people under 5 years old, people who are pregnant, anyone diagnosed with an eating disorder or who suspects they have one, people with growth disorders or conditions affecting height, and adults with a BMI over 35, for whom the measure stops being informative. The calculator above asks before it shows you anything, and will not show a number if you are in one of those groups.
If that applies to you, or the number worries you, the NHS advice is to speak to a pharmacist or GP rather than work it out alone.
What to do with the number
Measure it once, write it down, and leave it alone for a few months. Waist circumference moves slowly and fluctuates day to day with food, salt and fluid, so measuring weekly mostly generates noise and discouragement. The useful comparison is the same measurement, same place, same time of day, twelve weeks apart.
For the longer version — what the measure is a proxy for, and what the evidence does and does not say about shifting it — see how to measure belly fat at home.
What we could not verify
The NICE bands were read indirectly. NICE's website refused direct access, so the 0.4–0.49, 0.5–0.59 and 0.6+ figures come from a summary of its guideline rather than from the guideline page itself. The NHS rule of thumb and the list of people the calculator is not for were read directly from the NHS.
The BMI question is self-declared. Working out whether your BMI is over 35 needs your weight, which this calculator does not ask for and will not start asking for. It is a question you answer, not something computed, so it is only as accurate as what you know.
This does not measure you individually. Population thresholds describe risk across groups. They cannot tell you what is true of your body, and they are not a diagnosis.
Nothing here was tested. It is drawn from published guidance.