Waist-to-Height Ratio Calculator
See how your waist compares to your height
Waist-to-height ratio and health risk FAQ
What is waist-to-height ratio and how is it used?
Waist-to-height ratio (WHtR) is simply your waist circumference divided by your height, both in the same unit. For example, if your waist is 80 cm and your height is 170 cm, your ratio is about 0.47. Public health bodies increasingly use WHtR alongside BMI because it focuses on abdominal fat around the organs, which is strongly linked with long-term risk.
What is a “good” waist-to-height ratio?
Many guidelines suggest that adults aim to keep waist to less than half their height, so a ratio under 0.5. Ratios roughly between 0.4 and 0.49 are often described as a “healthy” band, 0.5 to 0.59 as “increased risk”, and 0.6 or more as “high risk” for problems like type 2 diabetes, high blood pressure and heart disease, especially when combined with other risk factors.
Why do people say waist can show risk earlier than BMI?
BMI looks only at weight vs height and cannot tell whether extra weight is muscle or fat, or where that fat sits. Waist-to-height ratio pays attention to central fat around the tummy, which can be high even when BMI looks “normal”. Studies have found that people with a healthy BMI but WHtR above 0.5 often have more cardiometabolic risk factors than those with lower ratios.
Does sex or ethnicity change the cut-offs?
Some research suggests small differences by sex and ethnicity, but a 0.5 boundary is often used as a simple global cut-off in adults. This tool keeps to that simple message while reminding you that individual risk also depends on family history, blood pressure, blood sugars, smoking, sleep and other factors your clinician will consider.
How do I measure my waist correctly?
Use a soft tape measure. Stand up, relax, breathe out gently and wrap the tape around your middle at about belly-button level or midway between the lowest rib and the top of the hip bone. Keep the tape snug but not digging into the skin, parallel to the floor. Use the same spot each time so changes are comparable.
How often should I check my waist-to-height ratio?
For most people, checking every few months is enough. Daily or weekly measurements add a lot of noise. If other risk factors are present or you are actively working on weight and activity changes, repeating the measurement a few times a year and sharing the pattern with your healthcare team can be more useful than watching the scale alone.
Who should not rely on this calculator alone?
People who are pregnant, growing children, elite strength athletes, or those with major medical conditions, eating disorders or recent surgery should not rely on WHtR alone. In those situations, body shape changes can have different meanings and always need personalised clinical input.
How to use this waist-to-height ratio calculator
The point of this page is to turn the advice to “keep your waist to less than half your height” into numbers you can actually track. Instead of guessing whether your waist is “too big for your frame”, you can see a simple ratio, a risk band, and the waist measurement that would keep you under that 0.5 cut-off.
1. Enter units, sex, height and waist
Choose the unit system you think in: US (ft/in, in) or metric (cm). In US mode, height is entered as feet plus inches and waist as inches. In metric mode, both are in centimetres. Pick your sex so the summary can use language that fits you, then enter your usual standing height and a relaxed waist measurement taken at a consistent point.
2. Read your ratio and risk band
Hit Check waist-to-height ratio to see:
- Your exact ratio to two decimal places.
- A simple risk band like “healthy”, “increased” or “high”.
- The waist measurement for your height that lines up with a ratio of 0.5 and 0.6.
The idea is to make it obvious whether changes over time are nudging you toward or away from higher risk bands, not to chase a perfect number.
3. Use the waist target, not just the label
For any height, this calculator shows a “keep it under this waist” number based on a 0.5 ratio. If your current waist is above that, you can see roughly how many inches or centimetres you would need to lose from the waist to drop into a lower risk band, while still remembering that how you make that change matters more than the change itself.
4. Combine WHtR with other signals
Waist-to-height ratio is one tool among many. Your clinician will also care about blood pressure, cholesterol, blood sugar, family history, smoking status, mental health and sleep. Use the summary button to copy your numbers into a note or message so you can bring concrete data, not just feelings, to your next check-up.
If you see your ratio climbing or staying high and you feel worried, that is a cue for a conversation, not panic. Sustainable changes in food, movement, stress and sleep, ideally with professional support, usually matter more than any single cut-off in a table.
How the waist-to-height ratio math and bands work
Behind the scenes this tool uses very simple maths so the logic is easy to follow and talk about with a clinician: it divides waist by height, then compares that number with a small set of cut-offs.
1. Converting everything into the same unit
The core rule is that waist and height must use the same unit. In US mode, your height in feet and inches is converted to total inches and compared with a waist measurement in inches. In metric mode, both height and waist stay in centimetres. The ratio is:
waist-to-height ratio = waist ÷ height
Because both values share the same unit, the units cancel out and the result is a pure number like 0.47 or 0.55.
2. Interpreting the ratio
Research and public health guidance often use 0.4, 0.5 and 0.6 as key checkpoints. A common simple scheme is:
- Below ~0.4: lower-than-typical waist for height (can be fine or a sign of other issues).
- 0.40–0.49: “healthy” central fat range.
- 0.50–0.59: “increased” central fat and higher long-term risk.
- 0.60 or more: “high” central fat and further increased risk.
The calculator uses these zones to label your result. It cannot see everything about your health, but it can nudge you to take a closer look sooner if your ratio is creeping up.
3. Turning cut-offs into waist targets
For your height, a ratio of 0.5 translates into a simple waist target:
waist at 0.5 = height × 0.5
waist at 0.6 = height × 0.6
The tool calculates these and shows them back in inches or centimetres so you can see the waist measurement that keeps you under the “half your height” line, and where the high-risk 0.6 zone would start.
4. Why WHtR is often used alongside BMI
Systematic reviews have found that waist-to-height ratio can be a better early-warning signal for cardiometabolic risk than BMI alone, particularly for people with “normal” BMI who still carry a lot of central fat. That is why some guidelines now recommend using both BMI and WHtR together rather than relying on BMI in isolation.
Even so, no single number can speak for your whole health story. This calculator is best treated as a conversation starter and tracking tool that works alongside the clinical advice, tests and treatment plans built around you.
References and further reading on waist-to-height ratio
These resources explain where the cut-offs and ideas in this tool come from:
- NHS — Calculate your waist to height ratio — outlines how to measure waist, calculate the ratio, and why many adults are advised to keep waist to less than half their height.
- Ashwell M, Gibson S — Waist-to-height ratio as an indicator of early health risk — BMJ Open paper showing that a WHtR cut-off around 0.5 can flag cardiometabolic risk even when BMI looks healthy.
- Yoo EG — Waist-to-height ratio as a screening tool for obesity and cardiometabolic risk — systematic review discussing why a 0.5 cut-off works across adults and older children in many populations.
- British Heart Foundation — Why your waist size matters — practical guide on measuring waist, interpreting results and linking central fat to heart risk.
Use these as background reading and combine your ratio with professional medical advice, especially if you have existing conditions or strong family history of cardiometabolic disease.