Waist to Height Ratio Calculator
Keep your waist under half your height. That is the whole rule, it needs no calculator, and it tracks health outcomes better than BMI does.
Waist to height
0.47
- Waist to height
- 0.47
- Category
- Healthy
- Half your height
- 90.0 cm
- Waist to hip
- 0.85
- Keep your waist under half your height. That is the whole rule, it needs no calculator, and it tracks health outcomes better than BMI does.
- The reason is that BMI cannot tell where weight sits, and abdominal fat is the part that carries the risk. Two people with identical BMIs can have very different waist-to-height ratios and very different odds.
- Measure at the midpoint between the lowest rib and the top of the hip bone, at the end of a normal breath out. Not at the trouser line, and not held in.
About waist-to-height ratio
BMI has one fundamental blind spot: it cannot tell where the weight sits. Two people of identical height, weight and BMI can carry it very differently, and abdominal fat is the part that carries the risk. It sits around the organs rather than under the skin, and it behaves differently in the body.
Waist-to-height is the correction. An 85cm waist on a 180cm frame is 0.47 — inside the healthy band, which runs to 0.50. Above that risk rises, and above 0.60 it rises sharply. The bands are the same for men and women and largely the same across ethnicities, which BMI thresholds are not.
The rule has an advantage no other measure has: you do not need the calculator. Half your height is a number you can remember, and a piece of string folded in half will check it. That is a genuinely useful property for something meant to be checked regularly.
Waist-to-hip is the other ratio in use and it is shown here too. It captures fat distribution rather than amount, and it is more sensitive to build. Waist-to-height is the more useful of the two for most people.
Where you measure matters more than which ratio you use. The midpoint between the lowest rib and the top of the hip bone, at the end of a normal breath out. Not at the trouser line, and not held in.
What it works out
- Waist-to-height ratio and its band
- Waist-to-hip ratio
- Half your height, as the number to remember
- Metric or imperial
The formula
Waist ÷ Height Healthy below 0.50
A division. 85 divided by 180 is 0.47, which sits inside the healthy band.
The bands are: below 0.40 is under the healthy range, 0.40 to 0.50 is healthy, 0.50 to 0.60 carries increased risk, and above 0.60 is high risk. The boundary at 0.50 is where "keep your waist under half your height" comes from, and it is the only threshold most people need.
Because both numbers are lengths, the units cancel. Inches against inches gives the same answer as centimetres against centimetres, which is why this measure works identically everywhere while BMI thresholds vary by population.
Waist-to-hip is the same idea applied differently: 85 over 100 is 0.85. It describes shape rather than size, and it is the older of the two measures.
- Waist
- Midway between the lowest rib and the top of the hip bone, breathing out normally.
- Height
- Standing, without shoes.
- Hips
- At the widest point, for the second ratio.
A worked example
An 85cm waist and 100cm hips on someone 180cm tall.
That works out to 0.47 .
- Waist to height
- 0.47
- Category
- Healthy
- Half your height
- 90.0 cm
- Waist to hip
- 0.85
Questions
What is a healthy waist-to-height ratio?
Below 0.50 — your waist under half your height. Between 0.50 and 0.60 indicates increased risk and above 0.60 is high risk. The same bands apply to men and women.
Is waist-to-height better than BMI?
For predicting cardiovascular and metabolic risk, generally yes. BMI cannot distinguish muscle from fat or say where fat sits, and abdominal fat is the part that matters most.
Where do I measure my waist?
Midway between the lowest rib and the top of the hip bone, at the end of a normal breath out, with the tape snug but not compressing. Not at the trouser line, which is usually lower and gives a flattering number.
Does the ratio differ for men and women?
The waist-to-height thresholds are the same for both, which is one of its advantages. Waist-to-hip thresholds do differ — around 0.90 for men and 0.85 for women — because hip proportions differ.
What is the difference between the two ratios?
Waist-to-height measures how much abdominal fat you carry relative to your size. Waist-to-hip measures the distribution — whether weight sits around the middle or lower down. The first is more useful for most people.
Can I be a healthy BMI and an unhealthy waist ratio?
Yes, and it is common enough to have a name. Someone with little muscle and central fat can sit squarely inside the healthy BMI band while carrying a waist-to-height ratio well above 0.50, which is exactly the case BMI misses.
Does this apply to children?
The rule of thumb is sometimes applied from about age five, but children are assessed against percentile charts by a clinician and nothing here attempts that.