Waist to Height Ratio Calculator
Work out your waist to height ratio and see which band it falls in, plus the 'half your height' target waist for you. Free, metric and imperial.
Midway between the lowest rib and the top of the hip bone
Standing, no shoes
Your waist is less than half your height — the range most commonly cited as healthy for adults.
This is a screening estimate, not a diagnosis. It cannot account for your age, ethnicity, muscularity, pregnancy, or medical history — talk to a clinician before acting on the result.
What waist to height ratio actually measures
Waist to height ratio (WHtR) is one of the simplest health screening numbers there is: divide your waist circumference by your height, in the same unit. Unlike BMI, which only knows your weight and height, WHtR is a proxy for central (abdominal) fat — the fat around your organs, which is the distribution most closely tied to cardiometabolic risk. Two people can share a BMI and have very different waistlines.
The reason the measure caught on is the memorable version of the rule: keep your waist to less than half your height. UK NICE guidance popularised exactly that phrasing, recommending waist to height ratio alongside BMI for adults with a BMI under 35. That is where the 0.5 boundary in this calculator comes from — and why the tool also shows the target waist measurement for your specific height.
The commonly cited bands
| Ratio | Commonly described as |
|---|---|
| Under 0.40 | Below the usual healthy range |
| 0.40 – 0.49 | Healthy range |
| 0.50 – 0.59 | Increased health risk |
| 0.60 and above | High health risk |
These thresholds are drawn from general adult guidance and are not tailored to age, ethnicity, pregnancy, muscularity, or any medical condition. They are screening cut-offs designed to flag “worth looking into”, not to label anyone as healthy or unhealthy.
Measure it the same way every time
Consistency beats precision here. Breathe out normally, put the tape midway between your lowest rib and the top of your hip bone, keep it level and snug without digging in, and take the reading at the same time of day each time. A centimetre of sloppy tape placement moves the ratio more than a month of genuine progress does, so the routine matters as much as the number.
The number moves when the daily habits do
Waist size is a lagging indicator. It responds to weeks of walking, training, sleep, and eating — not to any single day. So rather than re-measuring constantly, pick the two or three daily behaviours that drive it and make those the thing you check off. HabitBox is a habit tracker for iOS and Android that keeps those on your home screen: one tap to log a check-in, no account needed, and your data stays on your device. Pair it with a plan for staying consistent past week three and the tape measure takes care of itself.
Note: this is a screening estimate, not a diagnosis. Waist to height ratio cannot account for your medical history, body composition, age, ethnicity, or pregnancy. Talk to a clinician before acting on the result or making changes to your diet, training, or medication.
Frequently asked questions
What is a healthy waist to height ratio?+
The most commonly cited healthy band for adults is 0.40 to 0.49 — in plain terms, keep your waist measurement to less than half your height. A ratio of 0.50 to 0.59 is usually described as an increased health risk, and 0.60 or above as a high risk. These are population-level screening thresholds, not a personal diagnosis.
How do I measure my waist correctly?+
Stand up, breathe out normally, and put a flexible tape around your bare middle roughly midway between the bottom of your lowest rib and the top of your hip bone — for most people that is just above the belly button. Keep the tape snug but not compressing the skin, and keep it level all the way around. Measure at the same time of day each time so your readings stay comparable.
Is waist to height ratio better than BMI?+
It measures something different. BMI uses only weight and height, so it cannot tell where fat sits, while waist to height ratio is a proxy for central (abdominal) fat, which is the pattern most strongly linked to cardiometabolic risk. UK NICE guidance suggests using waist to height ratio alongside BMI for adults with a BMI under 35. Neither number is a diagnosis on its own.
Does the ratio change if I use inches instead of centimetres?+
No. Because both measurements are divided by each other, the units cancel out — as long as your waist and your height are measured in the same unit, the ratio is identical. This tool converts both values together when you switch, so the result stays the same.
How often should I re-measure?+
Waist size moves slowly, so once a month is plenty; weekly at most. What actually shifts it is the daily stuff — training sessions, walking, sleep, and what you eat. Tracking those as daily habits in an app like HabitBox gives you something to check off every day, instead of waiting on a tape measure that barely moves week to week.
Track the habits that shrink the number
Waist size responds to weeks of walking, training, and sleep — not to any single day. HabitBox lets you set those as daily habits and log a check-in in one tap. No account needed, your data stays on your device, on iOS and Android.
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