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Waist-to-height ratio calculator (WHtR)

Calculate an adult waist-to-height ratio and its equivalent percentage from waist and height measurements taken in the same selected unit, without diagnosing, classifying risk or setting a personal target.

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Calculate your result

Measure midway between the lower margin of the last palpable rib and the top of the hip bone, at the end of a normal breath out. Use the selected unit, no thousands separator and no more than one decimal place.

Accepted range: 20 to 400 cm

Enter standing height in the same selected unit, with no more than one decimal place. Use total inches rather than feet-and-inches notation, and do not type a unit in the field.

Accepted range: 50 to 250 cm

Your result will appear here

Nothing is saved or added to the URL.

What this result means

Waist-to-height ratio is waist circumference divided by standing height. When both measurements use the same unit of length, that unit cancels in the ratio. [1][4]

How to measure your waist consistently

Stand upright with arms relaxed. Place a non-stretch tape horizontally midway between the lower margin of the last palpable rib and the top of the iliac crest, usually called the top of the hip bone. Keep the tape snug without compressing skin and read it at the end of a normal breath out. [1][3]

Take repeat measurements with the same site, posture, tape tension and breathing point. If a clinician, research study or national programme gave you a different measurement protocol, use that protocol consistently rather than combining values from different sites. [3][5]

What the ratio and percentage mean

A ratio of 0.471 means the waist measurement is 0.471 times the height measurement. The equivalent 47.1% expresses the same relationship as a percentage. It is not a body-fat percentage and does not show where tissue is located or why a measurement changed. [1]

Centimetres and inches produce the same ratio when both fields use the same unit because that unit cancels in the division. One international inch is exactly 2.54 centimetres; the calculator does not need to convert the ratio itself. [4]

Why this result has no health-risk label

NICE describes adult waist-to-height classifications for people with BMI below 35 kg/m² and advises using the ratio alongside BMI and wider assessment. This calculator does not collect BMI, so applying those categories as a personal result would ignore an important eligibility condition. [1]

NHS guidance also says not to use its waist-to-height calculator to diagnose a condition and excludes pregnancy, adult BMI over 35, eating disorders and conditions that affect height. LongevityMate therefore keeps this page to neutral arithmetic and explains when not to interpret it. [2]

Australian Government and Health Canada adult guidance use BMI with waist circumference rather than establishing NICE waist-to-height categories as a universal worldwide rule. Interpretation therefore depends on the applicable local guidance and wider assessment. [5][6]

What can affect a repeat measurement

Tape placement, tightness, posture and breathing can all move the waist measurement. Protocol differences between a rib-to-hip midpoint and a navel-level measurement can also produce different values, so a small change should not automatically be treated as a body change. [3][5]

The displayed ratio and percentage are rounded outputs from the values entered. They do not provide a confidence interval, estimate measurement error or show whether a difference is medically important.

Safe next steps

If you want to repeat the calculation, record the measurement site and use the same tape method and unit. If the result worries you, you cannot use the stated protocol safely, or an exclusion applies, discuss the measurement in context with a qualified health professional rather than acting on this ratio alone. [1][2]

Formula and assumptions

Formula
WHtR = W ÷ H; % = WHtR × 100 [1][4]
Version
Adult waist-to-height ratio, adult-raw-waist-to-height-ratio-v1
Rounding
Use exact decimal arithmetic. Round the ratio once to three decimal places and the percentage independently from the same unrounded values to one decimal place, using half-up rounding. The supported 0.1-unit input resolution does not imply clinical precision.
Worked example
A waist circumference of 80 cm and a standing height of 170 cm give 80 ÷ 170 = 0.470588…. The ratio displays as 0.471. Calculated independently from the same unrounded values, the equivalent percentage is 47.1%. Entering 31.5 in and 66.9 in gives the same displayed results at the supported input precision. [4]

Who this is for — and when not to use it

Intended use

Neutral general-wellness arithmetic for adults aged 18 and over who have a waist circumference and standing height measured in the same selected unit and want the raw ratio and equivalent percentage only.

Not intended for

This tool does not calculate BMI or body-fat percentage, diagnose central adiposity or any condition, classify health risk, decide whether a result is healthy, high, low or optimal, set a personal waist target, replace a professional assessment, or guide weight-loss, diet, exercise, medication, supplement or treatment decisions.

Exclusions

  • Children and adolescents under 18; child waist-to-height pathways require age-appropriate assessment
  • Pregnancy or lactation-related interpretation
  • A diagnosed or suspected eating disorder, or use as a body-checking or body-target tool
  • BMI of 35 kg/m² or more for NICE waist-to-height interpretation; this calculator does not collect or assess BMI
  • Growth disorders, scoliosis, limb loss or another condition that alters standing height or requires a specialist height estimate
  • Ascites, pregnancy, a major abdominal mass or another condition that materially changes waist circumference
  • Recent abdominal surgery or a situation in which waist measurement is painful, unsafe or medically restricted
  • Measurements taken in different units or with different waist protocols
  • Feet-and-inches notation, text, ranges, inequality signs or a unit typed into a numeric field
  • Diagnosis, risk scoring, treatment decisions or personal target setting

Evidence sources

  1. 1. Identifying and assessing overweight, obesity and central adiposity — NICE guideline NG246 — National Institute for Health and Care Excellence. Accessed Aug 17, 2026.
  2. 2. Calculate your waist to height ratio — National Health Service. Accessed Aug 17, 2026.
  3. 3. Waist circumference and waist–hip ratio: report of a WHO expert consultation — World Health Organization. Accessed Aug 17, 2026.
  4. 4. NIST Guide to the SI, Appendix B: Conversion Factors — National Institute of Standards and Technology. Accessed Aug 17, 2026.
  5. 5. Body mass index (BMI) and waist measurement — Australian Government Department of Health, Disability and Ageing. Accessed Aug 17, 2026.
  6. 6. Canadian Guidelines for Body Weight Classification in Adults — Quick Reference Tool for Professionals — Health Canada. Accessed Aug 17, 2026.