Body Shape Calculator

What the five body shapes describe

A body shape calculator compares three tape measurements: the bust at its fullest point, the waist at its narrowest, and the hips at their widest. The shape name is shorthand for how those three numbers relate to each other. It says nothing about weight, fitness or dress size on its own: a 34-26-36 body and a 44-34-46 body can both read as hourglass.

The labels come from clothing fit guides, not from a medical handbook. Retailers, pattern makers and stylists use them because the same fitting advice holds across a wide range of sizes: a pear shape usually needs more room at the hip than at the shoulder, an inverted triangle needs the reverse, and an hourglass benefits from a waist seam. Treat the name as a fitting shortcut, nothing more.

Two numbers on this page do come from clinical guidance. The waist-to-hip ratio and the waist circumference are both used as cheap screening measures for fat stored around the belly, and both have published cut-offs. The shape label is fashion; those two ratios are health signals. Sections further down explain what each one can and cannot tell you.

The two tests behind every shape name

Every shape rule on this page reduces to two comparisons. The first asks whether the bust and hips are close in size, which here means within 5% of each other. The second asks whether the waist is at least 25% smaller than the bust, which is the same as the waist measuring 75% of the bust or less.

Take a 38 in bust and 39 in hips. The difference is 1 in, and 1 ÷ 39 = 0.026, or 2.6%, so the two count as a match. Now take a 34 in bust and 42 in hips: 8 ÷ 42 = 0.19, so the hips are clearly wider and the body reads as a pear unless the waist is small enough to pull it back toward an hourglass.

The waist test is what separates hourglass from rectangle, and it moves faster than people expect. With a 38 in bust the line sits at 38 × 0.75 = 28.5 in. A 28 in waist clears it and an hourglass comes back. A 30 in waist misses it by an inch and a half, and the same body reads as a rectangle. The 5% and 75% lines are conventions, not laws; some other calculators use 0.8 instead of 0.75, which shifts a few bodies across the boundary. That is why two sites can give the same person two different labels.

How to measure bust, waist and hips

The shape is only as good as the three numbers, and most bad answers come from bad tape work. Use a flexible cloth or fiberglass tape, wear light clothing, and measure in front of a mirror so you can check the tape stays level all the way around.

• Bust: tape around the fullest part of the chest, level under the arms and across the shoulder blades. Keep the tape snug without squeezing.
• Waist: find the top of your hip bone and measure just above it, which is where federal survey staff place the tape, at the end of a normal breath out. This is usually above the navel, not at it, and never where your trousers sit.
• Hips: feet together, tape around the widest part of the buttocks, keeping it parallel to the floor.
• Measure twice. If the two readings differ by more than half an inch, take a third and use the middle value.

Those waist instructions are not a style choice. The CDC's NHANES survey manual, the protocol behind most published waist numbers, marks the measurement site at the upper border of the hip bone and records to the nearest 0.1 cm at the end of a normal expiration (see the CDC NHANES anthropometry procedures manual). Measuring the waist down at the beltline instead adds inches that belong to the hips, and the shape can flip from hourglass to apple for no real reason.

Measure the same way each time. Morning, before eating, tape snug, breathe out. Consistency is what turns a single reading into a trend you can trust.

Worked examples with real numbers

Five sets of measurements, run through the same two tests, show how the labels land.

Walk through the first one. Bust 38, hips 39: 1 ÷ 39 = 0.026, within the 5% band, so the question is the waist. The line is 38 × 0.75 = 28.5 in, and 28 is under it, so the answer is hourglass. The waist-to-hip ratio is 28 ÷ 39 = 0.72.

The second one fails the same waist test on purpose. Bust 34, waist 30: the line is 34 × 0.75 = 25.5 in, and 30 is far over it, so with the hips 8 in wider the label is pear. Note that the waist-to-hip ratio for this body, 30 ÷ 42 = 0.71, is lower than the hourglass example's. Shape and health ratio are different questions, which is exactly why the calculator reports both.

Metric measurements give the same labels. A 96 cm bust, 71 cm waist and 99 cm hips is the first body in centimeters: 3 ÷ 99 = 0.03, within 5%, and 96 × 0.75 = 72 cm, so 71 just clears the line. The ratios match too, because a ratio has no units.

Body shape and health risk: the two ratios that matter

Of everything on this page, only the apple end of the spectrum has a documented link to health, and the link runs through fat stored around the belly rather than through the shape name. The two screening numbers are the waist-to-hip ratio and the waist circumference on its own.

Those are the cut-offs the World Health Organization uses when it grades waist-to-hip ratio as a risk marker, and they apply at every age (see the WHO fact sheet on obesity and overweight). Waist circumference carries its own lines: more than 35 inches for women and more than 40 inches for men raises the risk of heart disease and type 2 diabetes regardless of the ratio, per the National Heart, Lung, and Blood Institute.

The interesting cases are the mismatches. A rectangle-shaped body with a 37 in waist on 40 in hips scores a 0.93 ratio, which is in the high-risk band for a woman even though the shape name sounds neutral. A bottom hourglass with a 25 in waist on 40 in hips scores 0.63 and is nowhere near a threshold. The label describes a silhouette; the ratio describes where fat sits.

Two cautions. Ratios are screening tools, not diagnoses: they cannot see blood pressure, blood sugar or family history, and athletes and pregnant women measure differently from the general population. And a shape label is not a risk grade. There is no evidence that being a pear rather than a rectangle predicts anything by itself; what predicts risk is a climbing waist over the years.

Using the shape for fit and shopping

Shape labels earn their keep in a fitting room, where the question is which garment will hang right. Four rules cover most of it.

• Pear: size to the hips and take in the top, or pick styles with detail above the waist. Straight-cut dresses sized to the waist will pull across the hip.
• Inverted triangle: size to the bust or shoulders and add volume below, such as an A-line skirt. Shoulder seams that sit right matter more than the number on the tag.
• Hourglass: anything that follows the waist, wrap tops, belted dresses. Boxy cuts hide the waist and gape at the bust.
• Rectangle: belts, peplums and layered tops create the waist the tape says is not there.
• Apple: open necklines and structured shoulders; drawstrings at the waist tend to sit at the widest point.

Two honest limits. Brand size charts do not agree with each other, so the same hip measurement can be a 10 in one store and a 14 in another; the shape tells you where to expect pull, not which tag to buy. And tailoring beats labels: a $15 waist adjustment usually does more than any rule about silhouettes.

What can change your shape, and what this tool cannot do

Shapes drift over years, not weeks. Weight change tends to show up at the waist first, which is why a modest 5 to 10% loss moves the ratios before it moves the label. Pregnancy shifts everything temporarily and can shift the waist reading for longer. Strength training can widen the shoulders or hips a little. Menopause redistributes fat toward the middle, so the same habits can turn a pear into an apple over a decade.

The math is sensitive near the boundaries. On the 38-28-39 body, a waist that moves from 28 to 29 in changes the waist-to-hip ratio from 28 ÷ 39 = 0.72 to 29 ÷ 39 = 0.74, still an hourglass. At 31 in the waist crosses the 28.5 in line and the label becomes rectangle with no change in bust or hips at all. Half an inch of tape slop can do the same, which is why the measuring section says to measure twice.

What this tool cannot do: it cannot tell you whether you are healthy, because shape and ratio are not diagnoses; it cannot see age, muscle mass, pregnancy or posture; and it cannot settle brand size charts, which disagree with each other more than the shapes do. It names a silhouette from three numbers and grades two screening ratios against published cut-offs. For anything medical, take the numbers to a clinician rather than the label to a search box.