Waist-to-Height Ratio Calculator
A healthy waist-to-height ratio is under 0.5, meaning your waist stays below half your height. This waist-to-height ratio calculator checks your measurements against National Institute for Health and Care Excellence bands.
How This Waist-to-Height Ratio Calculator Works
The National Institute for Health and Care Excellence (NICE) defines a healthy waist-to-height ratio as 0.4 to 0.49, indicating no increased health risks. Guideline NG246, which carries waist-to-height recommendations NICE first made in 2022, advises keeping your waist to less than half your height. A ratio under 0.5 meets that target. Ratios from 0.5 to 0.59 indicate increased health risks from increased central adiposity. Measurements of 0.6 or higher represent high central adiposity and further increased health risks.
| Ratio | NICE Classification | Health Risk Wording |
|---|---|---|
| 0.4 to 0.49 | Healthy central adiposity | No increased health risks |
| 0.5 to 0.59 | Increased central adiposity | Increased health risks |
| 0.6 or more | High central adiposity | Further increased health risks |
The waist-to-height ratio calculator divides waist circumference by height, displaying the result to two decimal places with the working. In NICE Box 1, an adult with a 38-inch waist and a height of 5 feet 7 inches (67 inches) has a ratio of 0.57. Dividing 96.5 cm by 170 cm yields the same 0.57 figure. You can choose feet and inches or centimeters. The calculator also shows half your height, marking the waist size to stay under. For a height of 5 feet 5 inches (65 inches), half is 32.5 inches. For 170 cm, half is 85 cm. Calculations run in your browser. The calculator is free and stores no entries unless you use the optional email box.
How to Measure Your Waist for the Ratio
Box 1 of NICE guideline NG246 sets out how to measure your waist. Find the bottom of your ribs and the top of your hip bones. Wrap the tape measure midway between these landmarks, just above your belly button. Breathe out naturally before taking the reading. Record both waist and height in the same unit. A height of 5 feet 7 inches equals 67 inches.
NICE recommends seeking clinical advice and further assessment from a healthcare professional if your measurement indicates an increased health risk. That consultation can include a cardiometabolic risk factor assessment.
Who the NICE Bands Apply To
The NICE waist-to-height ratio classifications apply to adults with a body mass index (BMI) under 35 kg/m2 of both sexes and all ethnicities. Recommendation 1.9.14 states these thresholds cover adults with high muscle mass. Central adiposity increases risks of type 2 diabetes, hypertension, and cardiovascular disease. Under recommendation 1.9.8, clinicians use waist-to-height ratio alongside BMI to assess central adiposity. NICE does not classify ratios below 0.4. Its healthy band starts at 0.4.
Waist-to-height ratio differs from measuring waist circumference alone. The National Heart, Lung, and Blood Institute (NHLBI) states that a waist circumference over 35 inches for women or over 40 inches for men increases health risks. The Centers for Disease Control and Prevention (CDC) defines adult BMI as weight in kilograms divided by height in meters squared. CDC categories classify BMI below 18.5 as underweight, 18.5 to less than 25 as healthy weight, 25 to less than 30 as overweight, and 30 or greater as obesity.
The waist-to-hip ratio calculator compares waist-to-hip ratio against sex-specific World Health Organization thresholds. The metabolic score tool provides a five-marker metabolic health score that includes waist circumference. The normal-weight insulin resistance guide covers insulin resistance in people with a normal BMI.
What You'll Get
- Waist-to-height ratio
- NICE central adiposity category
- Half your height: the waist measurement to stay under
What to Look For in a Body-Composition Scale
A bioimpedance scale trends body fat and muscle rather than just weight — useful when the number stalls but your composition is improving. The absolute body-fat % isn't lab-accurate, so use it for TRENDS at a consistent time of day. Choose one that syncs to an app so you can watch the trend line.
Frequently Asked Questions
What is a healthy waist-to-height ratio?
A healthy waist-to-height ratio is 0.4 to 0.49. The National Institute for Health and Care Excellence (NICE) classifies this range as healthy central adiposity with no increased health risks. NICE recommends keeping your waist circumference to less than half your height, which represents a ratio under 0.5.
What is my ideal waist size for my height?
Your ideal waist size is less than half your height. Multiply your height by 0.5 to find this measurement. For someone who is 5 feet 5 inches tall (65 inches), half of height is 32.5 inches. For a height of 170 cm, half is 85 cm. Keeping your waist below this number maintains a ratio under 0.5.
Is waist-to-height ratio better than BMI?
The National Institute for Health and Care Excellence (NICE) does not describe waist-to-height ratio as better than body mass index (BMI). Instead, NICE recommendation 1.9.8 advises using waist-to-height ratio alongside BMI for adults with a BMI under 35 kg/m2 to help assess risks of type 2 diabetes, hypertension, and cardiovascular disease.
Is a waist-to-height ratio below 0.4 good?
The National Institute for Health and Care Excellence (NICE) does not classify waist-to-height ratios below 0.4. In recommendation 1.9.14, the healthy central adiposity band begins at 0.4 and ends at 0.49.
Does the waist-to-height ratio differ for men and women?
The National Institute for Health and Care Excellence (NICE) uses the same waist-to-height ratio categories for both men and women. In contrast, the National Heart, Lung, and Blood Institute (NHLBI) publishes sex-specific waist cutoffs, warning that risks increase above 35 inches for women and above 40 inches for men.
How do I measure my waist correctly?
Find the bottom of your ribs and the top of your hips. Wrap a tape measure around your waist midway between these points, just above your belly button. Breathe out naturally before recording the measurement, and ensure you measure both your height and waist in the same unit.
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