Target Waist Size
The “waist under half your height” rule works across sexes and populations, which is why it is so widely quoted. At 172 cm the ceiling is 86 cm.
Your numbers
Target waist
86cm
Waist-height ratio
0.535
Difference
6cm
What it means
6 cm over target; a ratio of 0.535 is past 0.5.
Formula
Target waist = Height (cm) × 0.5
Measure at navel height after breathing out. Holding your stomach in or measuring over clothes reads smaller than reality.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Height (cm) (cm)Height in centimetres; converted to metres inside the formula. | 172 | 50 and up |
| Waist (cm) (cm)Waist at navel height, measured after breathing out. | 92 | 30 and up |
Step by step
Quick reference table
Results when only Height (cm) (cm) changes and everything else stays put.
| Height (cm) (cm) | Target waist (cm) | Waist-height ratio | Difference (cm) |
|---|---|---|---|
| 86 | 43 | 1.07 | 49 |
| 129 | 64.5 | 0.713 | 27.5 |
| 172 | 86 | 0.535 | 6 |
| 258 | 129 | 0.357 | -37 |
| 344 | 172 | 0.267 | -80 |
What each result means
| Result | At default values |
|---|---|
| Target waist (cm)Half your height — the ceiling your waist should stay under. | 86 |
| Waist-height ratioWaist over height; the line people watch is 0.5. | 0.535 |
| Difference (cm)The gap between two values — a quantity, not a rate. | 6 |
Common mistakes
Measure at navel height after breathing out. Holding your stomach in or measuring over clothes reads smaller than reality.
Glossary
- Height (cm)
- Height in centimetres; converted to metres inside the formula.
- Waist (cm)
- Waist at navel height, measured after breathing out.
- Target waist
- Half your height — the ceiling your waist should stay under.
- Waist-height ratio
- Waist over height; the line people watch is 0.5.
- Difference
- The gap between two values — a quantity, not a rate.
Frequently asked questions
Q. How is Target Waist Size calculated?
Target waist = Height (cm) × 0.5 — The “waist under half your height” rule works across sexes and populations, which is why it is so widely quoted. At 172 cm the ceiling is 86 cm.
Q. Can you walk through an example?
With Height (cm) 172cm, Waist (cm) 92cm, the answer is Target waist 86cm.
Q. What do I need to enter?
Enter Height (cm), Waist (cm). The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Height (cm) (cm) moves the answer to Height (cm) (cm) 86 → Target waist (cm) 43 and Height (cm) (cm) 344 → Target waist (cm) 172. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
Measure at navel height after breathing out. Holding your stomach in or measuring over clothes reads smaller than reality.
Related calculators
These calculators help you understand health figures; they do not replace diagnosis or prescription. See a clinician if you have symptoms.