Why "half your height"?

Ashwell's 2005 paper noted that the simple "keep your waist below half your height" rule corresponds to a WHtR cutoff of 0.50 — easy to remember, applies across populations, and works for children too. The 2012 meta-analysis confirmed the cutoff for adults.

Does WHtR work for children?

Yes — that is one of WHtR's advantages over BMI for kids. The same 0.5 cutoff applies from age ~6 onward, so a child whose waist is more than half their height needs evaluation regardless of BMI percentile.

Are the cutoffs the same for all ethnic groups?

The 0.5 healthy upper bound holds approximately across most adult populations in the Ashwell meta-analysis. Some authorities recommend a slightly lower cutoff (~0.48) for South and East Asian adults due to higher visceral fat at lower waist sizes.

Should I use this or waist-hip ratio?

WHtR uses one body measurement (waist) and a value you already know (height), so it is faster and easier than WHR. The 2012 meta-analysis found WHtR statistically slightly better than WHR. If you have data for both, prefer WHtR.

Waist-to-Height Ratio (WHtR) Calculator

A simple cardiometabolic-risk screen — keep your waist below half your height. Better than BMI for visceral-fat risk per Ashwell 2012.

Result

Waist-to-Height Ratio

0.50

Borderline

Overweight (consider action)

Cardiometabolic risk bandOverweight (consider action)Borderline
"Below half your height" target waistexactly at the half-height target85.0 cm (= height ÷ 2)
Healthy WHtR window0.40 – 0.50
Ashwell action thresholdPer Ashwell, Gunn & Gibson, Obes Rev 2012 meta-analysis — WHtR > 0.5 outperformed BMI/WHR for predicting cardiometabolic risk.> 0.50 → trim waist

Overweight (consider action)— Above 0.50 — Ashwell 2012 meta-analysis flags rising cardiometabolic risk; trim ~5 cm/2 in waist if feasible.

0.3 WHtR0.5 WHtR0.7 WHtR

"Keep your waist circumference less than half your height" — Ashwell 2005; thresholds 0.40 / 0.50 / 0.60 from Ashwell 2012 meta-analysis.

Your WHtR

exactly at the half-height target

0.50

Healthy upper bound (Ashwell)

"Keep your waist circumference less than half your height" — single-rule public-health message.

0.50

Action threshold (Ashwell 2012)

Above this, cardiometabolic-risk OR is markedly higher in pooled meta-analysis (n > 300,000).

> 0.50

Source: Ashwell M, Gunn P, Gibson S. Waist-to-height ratio as an indicator of "early health risk": simpler and more predictive than using a "matrix" based on BMI and waist circumference. Obes Rev 13(3):275-86 (2012).

Not medical advice — WHtR is a screening tool, not a diagnosis. Pregnancy invalidates the ratio as a cardiometabolic indicator. Some authorities recommend lower cutoffs for South Asian and East Asian populations. Discuss readings ≥ 0.50 with a clinician if you also have other risk factors.

How to use this calculator

Measure waist at the midpoint between the lowest rib and the iliac crest, tape parallel to the floor, relaxed.
Measure standing height without shoes.
Use the same units for both (the ratio cancels units out).
Take measurements in the morning, before eating, for the most consistent trend tracking.

About this tool

Waist-to-height ratio (WHtR) is one of the simplest cardiometabolic-risk screens: divide your waist circumference by your height, in any consistent unit. The 2012 Ashwell meta-analysis (Obesity Reviews, n > 300,000) found that WHtR outperformed both BMI and waist-hip ratio for predicting cardiovascular events, type 2 diabetes, and all-cause mortality. The headline rule: "keep your waist circumference less than half your height" — i.e., WHtR < 0.5. Bands: under 0.4 (possible underweight), 0.4–0.5 (healthy), 0.5–0.6 (overweight, consider action), above 0.6 (high risk).

How it works — the formula

WHtR = waist circumference ÷ height (same unit)

Both measurements must be in the same unit; the ratio is dimensionless. Bands: < 0.40 underweight risk, 0.40–0.50 healthy, 0.50–0.60 overweight, > 0.60 high risk. The 0.50 cutoff is the most-cited single threshold ("keep your waist below half your height") and was the central finding of the 2012 Ashwell meta-analysis.

Sources: Ashwell M, Gunn P, Gibson S. Waist-to-height ratio as an indicator of "early health risk": Obesity Reviews 13(3):275-86 (2012). · Ashwell M, Hsieh SD. Six reasons why the body mass index should be replaced by the waist-to-height ratio. Int J Food Sci Nutr 56(5):303-7 (2005). · NICE Guideline NG7 — Maintaining a healthy weight (UK), referencing WHtR < 0.5 for adult healthy weight.

Worked examples

Example 1

Healthy adult

Inputs:: waist = 80 cm, height = 175 cm
Output:: WHtR = 80/175 = 0.46 → Healthy (within 0.40–0.50 band)

Example 2

Above the half-height rule

Inputs:: waist = 95 cm, height = 175 cm
Output:: WHtR = 95/175 = 0.54 → Overweight (consider action)

Example 3

Imperial / metric agree (ratio is dimensionless)

Inputs:: waist = 32 in, height = 70 in
Output:: WHtR = 32/70 = 0.46 — same band as 81 cm / 178 cm

Limitations

Pregnancy temporarily invalidates WHtR as a cardiometabolic indicator.
Some authorities recommend a lower cutoff (~0.48) for South Asian and East Asian adults.
WHtR is a screen, not a diagnosis — readings near or above 0.50 should prompt a fuller assessment (BMI, body-fat %, blood pressure, lipids, glucose) rather than action based on WHtR alone.
Tape placement matters: WHO protocol places the waist tape at the midpoint between the lowest rib and iliac crest. The "navel" landmark used informally is usually within 1 cm of this and acceptable for self-tracking.

WHtR is a screening indicator, not a diagnosis. This calculator does not provide medical advice — discuss readings ≥ 0.50 with a clinician, especially if combined with other cardiometabolic risk factors.

Frequently asked

BMI ignores fat distribution. Two people with the same BMI can have very different cardiometabolic risk depending on how much fat sits around the abdomen. WHtR captures that distribution with one easy measurement and was found to outperform BMI in pooled meta-analysis (Ashwell 2012, Obes Rev).