Body Composition
Estimate your frame size and somatotype tendency from height and wrist circumference.
Frame Size
Small
Mesomorph tendency
Frame size uses your height-to-wrist ratio; somatotype is a tendency estimate based on frame and general body composition patterns. This is an anthropometric screening tool, not a medical assessment.
Frame size is determined by dividing your height (in cm) by your wrist circumference (in cm). A higher ratio indicates a smaller frame; a lower ratio indicates a larger frame. Wrist circumference reflects bone structure and is relatively stable throughout life. Somatotype is a classification system describing three body shape tendencies: ectomorphs (lean, low body fat naturally), mesomorphs (athletic, responsive to training), and endomorphs (naturally rounder, easier fat gain). Most people are a blend, but identifying your tendency helps personalise training and nutrition.
Enter your height and wrist circumference in either metric (cm) or imperial (inches). The calculator divides height by wrist circumference to produce a ratio. For males, a ratio below 9.6 indicates a large frame, 9.6–10.4 is medium, and above 10.4 is small. For females, the thresholds are adjusted (below 10.9 is large, 10.9–11.9 is medium, above 11.9 is small) because women typically have smaller frames. The tool then combines frame size with an estimated BMI pattern to suggest a somatotype tendency.
Height–to–wrist ratio = Height (cm) ÷ Wrist circumference (cm)Measure your wrist circumference at the narrowest point (just above the wrist bone) using a soft measuring tape. Divide your standing height in centimetres by that wrist circumference in centimetres. A ratio near 10 is typical for an average adult. The sex-specific thresholds account for differences in skeletal proportions between males and females.
| Input | Result | Notes |
|---|---|---|
| Male, 180 cm tall, 18 cm wrist | Ratio = 10.0 (Medium frame) with Mesomorph tendency | Medium frame suggests balanced proportions; mesomorph tendency indicates good responsiveness to strength training and muscle gain potential. |
| Female, 165 cm tall, 15 cm wrist | Ratio = 11.0 (Medium frame) with Mesomorph tendency | Medium frame for women is typical; mesomorph suggests athletic potential and moderate natural muscle-building capacity. |
| Male, 175 cm tall, 16 cm wrist | Ratio = 10.9 (Small frame) with Ectomorph tendency | Small frame with ectomorph tendency suggests a naturally lean build; weight gain may require surplus calories and consistent resistance training. |
Wrist circumference is a stable, objective measure of bone structure. It doesn't change with fat or muscle gain, making it ideal for assessing frame size independent of current body composition.
Your skeletal frame is fixed, but body composition (muscle and fat) is highly trainable. With the right diet and training, an ectomorph can build muscle, or an endomorph can lean out. Somatotype is a tendency, not destiny.
Frame size is based on skeletal proportions (height-to-wrist ratio). Somatotype blends frame size with natural fat and muscle tendencies. A large-framed person can be lean (mesomorph) or carry fat easily (endomorph).
Ratios near the boundary (e.g., 9.6 or 10.4 for males) are borderline. You may identify with two adjacent categories; use the one closest to your measurements and adjust your approach based on real results.
Ectomorphs: higher calorie intake, lower reps, longer rest. Mesomorphs: balanced approach, responsive to most programs. Endomorphs: higher conditioning work, more frequent training, attention to diet.
Frame size (skeletal structure) stays constant, but body composition changes. Metabolism slows with age, so endomorphs may need to adjust calorie intake; muscle maintenance requires consistent strength training at any age.