Body Composition
Waist that reaches a chosen ratio
Rearranging the definition gives the waist that would land exactly on a threshold, which is how the 0.90 line is turned into centimetres.
The Formula
waist = targetRatio x hip
Rearranging the definition gives the waist that would land exactly on a threshold, which is how the 0.90 line is turned into centimetres.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| targetRatio | The threshold you are testing against | dimensionless | 0.90 for men and 0.85 for women under the WHO guidance. |
| hip | Hip circumference held fixed | length | At 100 cm, the target waist for the male line is 0.90 x 100 = 90.0 cm. |
| waist | Waist that produces that ratio | length | The boundary value rather than a measurement you have taken. |
What Each Symbol Means
targetRatiodimensionless
The threshold you are testing against
0.90 for men and 0.85 for women under the WHO guidance.
hiplength
Hip circumference held fixed
At 100 cm, the target waist for the male line is 0.90 x 100 = 90.0 cm.
waistlength
Waist that produces that ratio
The boundary value rather than a measurement you have taken.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate waist to hip ratio page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate Waist To Hip Ratio, filed under Health. Every number the guide produces comes from substituting into this one line.