Divide matching measurements
| Input | Value | Use in the calculation |
|---|---|---|
| Waist circumference | 78 cm | Numerator |
| Hip circumference | 102 cm | Denominator |
| Waist-to-hip ratio | 0.7647 | 78 ÷ 102 |
The calculation is waist ÷ hip. Both inputs must use the same unit. In the example, centimetres divide by centimetres, so the final ratio has no unit. You can use inches instead when both measurements use inches.
Use a named measurement method
A different tape location can change either input. Keep the tape level and record the units, date, and method. Do not substitute clothing sizes or a measurement taken for a different purpose.
Round after dividing
Keep enough digits to check the arithmetic, then apply the display rounding. The 78 cm and 102 cm example gives 0.7647 before rounding and 0.76 at two decimal places. The rounded number is a display choice. It does not make the measurements more precise.
Do not divide centimetres by inches. Convert one input first, or measure both again in the same unit. A calculator can perform the division, but it cannot confirm that the two tape readings used the same landmarks.
Keep the ratio in scope
Waist-to-hip ratio is an arithmetic result from two circumferences. It is not a direct measurement of body fat and does not diagnose a condition for an individual. The WHO report also describes variation in measurement protocols and populations, so do not apply a value from one source as a personal conclusion.
- Record the waist value, hip value, and unit.
- Record the waist and hip landmarks used.
- Divide waist by hip before rounding.
- Keep the date and measurement conditions when you compare results.
Use the waist-to-hip ratio calculator for the division. Use the tape-measure guide when you need to record repeatable inputs.
Common questions
Can I use inches for waist-to-hip ratio?
Yes. Use inches for both the waist and hip measurements. You can also use centimetres for both. The units cancel when you divide one matching measurement by the other.
Why can two waist-to-hip ratios differ?
The waist or hip landmark, tape position, posture, tension, units, or rounding can differ. Record the method with the result before comparing dates or sources.
Does waist-to-hip ratio measure body fat directly?
No. It is a ratio made from two circumference measurements. It does not directly measure body fat or diagnose a condition.
CHECK THE EVIDENCESources & limitations1 source
Sources checked September 22, 2026. These notes explain methods and assumptions. They have not received an independent clinical review.
