How the shape is selected
The revised FFIT method compares bust, waist, high hip and full hip. Its published boundaries are in inches, so the calculator converts every centimetre measurement by the exact factor 2.54 cm per inch before applying the rules. The first matching rule determines the displayed label.
It checks hourglass, bottom hourglass, top hourglass, spoon, triangle, inverted triangle, rectangle, diamond and oval in that order. For example, 91.44 cm bust, 66.04 cm waist, 86.36 cm high hip and 91.44 cm full hip correspond to 36, 26, 34 and 36 inches and meet the hourglass rule.
The result includes the reason for the match, bust-minus-hip and hip-minus-waist differences, and waist divided by full hip. These numbers describe the entered measurements; the waist-to-hip ratio is shown without a health-risk category.
Take the measurements
Use one flexible tape, keep it level, stand naturally and avoid pulling it tight. Bust or chest is the fullest part of the upper torso; waist is the natural waist; high hip is the upper hip below the waist; full hip is the widest part of the hips and seat. Measure each location consistently.
Choose centimetres or inches above the four fields. Switching units converts the displayed measurements while preserving their value for the calculation. High hip is needed to distinguish spoon and bottom-hourglass rules.
What the label means
The modified FFIT rules were developed for apparel research and adjusted after investigators found the older rules could misclassify larger midsections. Oval and diamond cover some cases that the earlier seven-category scheme missed. When none of the published rules fits, the calculator says No FFIT match instead of forcing a category.
A tape position or different waist definition can change a borderline label. The underlying research used measured female body scans, including US and Korean samples, so a shape label is not a universal identity, a clothing size, a diagnosis or a target for diet or exercise. People with other body proportions may find a different fit system more useful.
Inputs for the body shape calculator
Bust or chest circumference
Measure around the fullest upper-torso circumference with the tape level. Use the unit selected above the fields.
Waist circumference
Use your natural waist and measure without compressing the skin. The exact tape location affects a shape near a boundary.
High-hip circumference
Measure the upper hip below the waist. The high-hip-to-waist ratio separates spoon and bottom hourglass.
Full-hip circumference
Measure the widest part of the hips and seat, keeping the tape horizontal.
CALCULATOR QUESTIONS
Body shape calculator questions
Is this a medical body-shape classification?
No. FFIT is an apparel silhouette scheme. The result does not measure body fat, fitness or disease risk.
Why do I need a high-hip measurement?
Two of the published shape rules compare high hip with waist. Without that measurement, the calculator cannot faithfully distinguish spoon from bottom hourglass.
What if no shape matches?
No FFIT match means the four measurements do not satisfy any published rule. Recheck tape placement if appropriate; the calculator does not force a label.
Can I use inches?
Yes. Select inches above the four fields. One international inch is exactly 2.54 centimetres, and the published rule thresholds are in inches.
Why might another calculator return a different shape?
Calculators can use different shape systems, measurements and rule order. A few millimetres near a boundary or a different waist position can also change the result.