Waist-to-height ratio is one division, but a useful answer starts with a consistent measurement. Moving the tape to whichever position gives the smallest number changes the comparison before you even calculate it.

Find the bottom of the ribs and the top of the hips. Place the tape midway between them, keep it level, and breathe out naturally. Do not deliberately pull your abdomen in.

Use the same units for waist and height. Eighty-four centimetres divided by one hundred seventy-five centimetres equals zero point four eight. Centimetres divided by inches would give a meaningless comparison.

NICE uses this measure alongside BMI for adults with BMI below thirty-five. It can add screening information, but it does not diagnose a disease or measure an exact body-fat percentage for you.

Record the measurements, units and date. If the number changes, check your method before assuming a major change in your body. A consistent record is more useful than repeated adjustments during one session.

A ratio cannot choose a supplement or treatment. Put it alongside the wider health picture. The full guide below includes worked examples, interpretation limits and the common measurement mistakes to avoid.