Body shape categories — pear, apple, hourglass, rectangle, inverted triangle — come from the clothing industry, not from medicine. They were developed to solve a fitting problem: two people with identical dress sizes can need completely different garment patterns because their bust, waist and hip proportions differ. This body shape calculator takes those three measurements and applies a set of proportion rules, and it publishes the rules in full so you can see exactly why it produced the answer it did.
Arb Digital has built this as a measurement tool with a deliberately narrow scope. It classifies proportions. It does not assess health, it does not estimate body composition, it does not suggest what anyone should wear or change, and it draws no inference from the category it returns. The categories are descriptive labels for measurement patterns, and that is the entire claim this page makes about them.
What This Body Shape Calculator Does
It takes bust, waist and hip circumferences, computes two ratios and one relative difference, and applies a five-rule decision list to place the result in one of five categories. It also shows the ratios themselves, because the ratios carry more information than the label does — two people can share a category while sitting at opposite ends of it.
This is a different job from the ratio tools we already publish. Our waist to hip ratio calculator returns a single number, waist divided by hip, and nothing else; it does not classify a shape and does not use the bust measurement at all. That is the boundary between the two pages: that one owns the ratio, this one owns the three-way proportion classification. The waist to height ratio calculator uses height instead of hips, a third distinct measurement again.
For skeletal build rather than soft-tissue proportion, our body frame size calculator uses wrist circumference and height, which is stable through weight change in a way that none of the three measurements on this page are.
How to Use It
- Measure all three in the same units. The classification uses ratios, so inches and centimetres give identical answers as long as you do not mix them.
- Keep the tape level. A tape that rides up at the back is the single most common source of error, and it inflates the reading.
- Breathe out normally for the waist. Do not hold your stomach in, and do not pull the tape tight. Measure at the natural waist between the lowest rib and the top of the hip bone.
- Leave the tolerance at 5 percent unless you have a reason. It controls how close bust and hip must be to count as balanced, and the rule set below spells out what it affects.
- Read the ratios alongside the label. A borderline case is far better described by its numbers than by whichever side of the line it landed on.
The Rule Set, Stated in Full
Write B for bust, W for waist and H for hip. The tool computes the bust-to-hip difference as (B − H) ÷ H, expressed as a percentage, and calls the tolerance t, which defaults to 5 percent. The rules are applied in this order and the first match wins:
- If W is greater than or equal to both B and H, the category is apple, because the waist is the widest of the three.
- Otherwise, if the bust-to-hip difference is −t percent or lower — hips wider than bust by more than the tolerance — the category is pear.
- Otherwise, if the bust-to-hip difference is +t percent or higher, the category is inverted triangle.
- Otherwise bust and hip are balanced within the tolerance. If W ÷ H is 0.75 or below, the category is hourglass.
- Otherwise, if W ÷ H is 0.85 or above, the category is apple. If it falls between, the category is rectangle.
Work the default through. Bust 36, waist 28, hip 39 inches. The waist is not the largest, so rule 1 does not fire. The bust-to-hip difference is (36 − 39) ÷ 39 = −7.7 percent, which is below −5, so rule 2 fires and the category is pear. For reference the other figures are W ÷ H = 28 ÷ 39 = 0.718 and W ÷ B = 28 ÷ 36 = 0.778.
Where These Categories Came From
The systematic version of this idea is the Female Figure Identification Technique, developed at North Carolina State University's College of Textiles and published by Karla P. Simmons, Cynthia L. Istook and Priya Devarajan as "Female Figure Identification Technique (FFIT) for apparel part I: Describing female shapes" in the Journal of Textile and Apparel, Technology and Management, volume 4, issue 1, in June 2004. FFIT defines nine shapes rather than five — hourglass, bottom hourglass, top hourglass, spoon, rectangle, diamond, oval, triangle and inverted triangle — and it uses additional measurements including high hip and abdomen, not just the three on this page.
This calculator implements a simplified five-category rule set of its own, published above, and it is important to be exact about that. It is not FFIT, it does not use FFIT's coefficients, and it will not always agree with FFIT for the same body. What it shares with FFIT is the underlying idea: that proportions between measurements describe shape better than any single measurement does. Where the two differ, FFIT is the more granular system and the more carefully validated one, developed for apparel sizing rather than for a web page.
The everyday vocabulary — apple and pear in particular — predates all of this and comes from a much older habit of describing where weight sits on the body. Those words carry connotations that measurements do not, which is a reason to prefer the ratios over the labels when precision matters.
Measurement Technique Decides the Answer
All three inputs are tape measurements, and tape measurements are less reproducible than they look. There is no universal agreement on exactly where the waist should be measured; a paper on digital anthropometry, Digital Anthropometry for Body Circumference Measurements: European Phenotypic Variations throughout the Decades, notes there is no universal consensus on optimal waist measurement protocols and describes the bust as the circumference at the forwardmost protruding point above the waist and the hips as the rearmost protruding point below it.
Practically, three things move a reading. Tape tension: a tape pulled tight compresses soft tissue and reads low, and a slack tape reads high, easily by an inch. Tape level: a tape that slopes measures a longer path around the body and inflates the figure. And breathing: holding a breath or holding the stomach in can change a waist reading by more than the width of any threshold on this page.
Because the classification depends on differences of a few percent, an inch of error in either the bust or the hip can flip the category. Measure three times, keep the tape level, and use the median. If the readings straddle a rule threshold, the honest description is the pair of ratios, not the label.
What a Shape Category Cannot Tell You
Circumference measurements do not distinguish between the tissues they enclose. Two people with identical waist measurements can have very different underlying composition, and no tape can separate muscle, fat distribution and skeletal width. A review of the field, Use of Anthropometry for the Prediction of Regional Body Tissue Distribution in Adults: Benefits and Limitations in Clinical Practice, sets out those limits directly, noting among other things that abdominal wall tension influences waist circumference readings and that inter-individual differences in tissue composition can lead to erroneous classification of subjects even when group-level correlations are strong.
That is the reason this page classifies and stops. The three measurements are enough to describe a proportion; they are not enough to describe a body, and they are nowhere near enough to say anything about health. Where our other measurement tools reproduce published references, they do so with the same restraint: the BMI calculator returns a ratio and its published categories, and the relative fat mass calculator applies a published equation, neither of them offering a verdict.
Shape also changes. Bust, waist and hip measurements shift with age, with weight, through pregnancy and postpartum, with training, and with menopause. A category is a snapshot of three numbers on one day, not a fixed property of a person, and re-measuring after any of those changes will often produce a different label from exactly the same body.
Arb Digital builds sizing tools and product content that cut returns and help shoppers buy with confidence.
See Web Design Services Talk To Our TeamCommon Mistakes to Avoid
- Mixing units between the three measurements — the rules are ratio-based, so one figure in centimetres among inches produces nonsense.
- Pulling the tape tight — compression reads low, and the thresholds here are only a few percent wide.
- Holding your stomach in — a waist measurement taken on a held breath is not the measurement the rules expect.
- Measuring the hips too high — the hip figure is the fullest point below the waist, and taking it at the hip bone instead reads several inches low.
- Reading a health meaning into the label — these categories come from apparel fitting and carry no clinical information whatsoever.
Related Free Tools From Arb Digital
Get the single ratio on its own with the waist to hip ratio calculator, use height as the denominator with the waist to height ratio calculator, look at skeletal build with the body frame size calculator, compute BMI with the BMI calculator, or apply a published equation with the relative fat mass calculator. The free online tools hub lists every measurement tool we publish.
Frequently Asked Questions
Measure bust, waist and hip in the same units, then compare them. This tool computes the bust-to-hip difference as a percentage and the waist-to-hip ratio, and applies the five ordered rules published on this page to return a category.
Under this tool's rule set, bust and hip within the tolerance of each other, which defaults to 5 percent, and a waist-to-hip ratio of 0.75 or below. Different published systems use different thresholds.
Which of bust and hip is larger. If hips exceed bust by more than the tolerance the tool returns pear; if bust exceeds hips by more than the tolerance it returns inverted triangle.
A waist to hip ratio calculator returns one number, waist divided by hip, and does not use the bust measurement. This page uses all three measurements and returns a proportion category rather than a ratio.
No. FFIT, published by Simmons, Istook and Devarajan in 2004, defines nine shapes and uses additional measurements including high hip and abdomen. This tool applies its own simplified five-category rule set, published in full above, and will not always agree with FFIT.
Because the thresholds are only a few percent wide. Tape tension, tape level and breathing can each move a reading by an inch, which is enough to cross a boundary. Measure three times and use the median.
No. These categories come from the apparel and sizing literature and exist to help fit clothing. Circumference measurements cannot distinguish between the tissues they enclose, and this page draws no health inference at all.
Yes. Bust, waist and hip measurements shift with age, weight, pregnancy and postpartum changes, training and menopause. The category describes three numbers on one day rather than a fixed property.
This page classifies measurements you enter, for general information only. It is not medical advice, it makes no assessment of anyone's health or body composition, and any question about your body or your health belongs with a doctor or registered dietitian.
