Calculate belly size as the difference between your waist and hip circumference, entered in inches, cm, mm or feet, with the result in your chosen unit.
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Belly Size Formula
The belly size calculator subtracts hip circumference from waist circumference after converting both measurements to the same unit.
- BS = waist-minus-hip circumference difference
- W = waist circumference
- H = hip circumference
If the waist and hip measurements are entered in different units, the calculator first converts both values to inches:
- Win = waist circumference converted to inches
- Hin = hip circumference converted to inches
- CW = waist unit conversion factor to inches
- CH = hip unit conversion factor to inches
- BSout = circumference difference in the selected output unit
- Cout = output unit conversion factor from the selected unit to inches
A positive result means your waist circumference is larger than your hip circumference. A negative result means your hip circumference is larger than your waist circumference. A result of 0 means the two circumferences are equal.
Unit Conversion Factors Used
The calculator uses inches as the base unit, based on 1 inch = 2.54 cm exactly. Decimal conversion factors below are rounded.
| Unit | Conversion to Inches | Example |
|---|---|---|
| in | 1 | 40 in = 40 in |
| cm | 0.393700787 | 100 cm = 39.3701 in |
| mm | 0.0393700787 | 1000 mm = 39.3701 in |
| ft | 12 | 3 ft = 36 in |
How to Read the Belly Size Result
| Result | Meaning |
|---|---|
| Positive | Your waist circumference is larger than your hip circumference. |
| Negative | Your hip circumference is larger than your waist circumference. |
| 0 | Your waist and hip circumferences are equal. |
Example Problems
Example 1: Waist and hip in inches
Suppose your waist circumference is 38 in and your hip circumference is 42 in.
The belly size is -4 in. This means the hip circumference is 4 inches larger than the waist circumference.
Example 2: Waist in centimeters and hip in inches
Suppose your waist circumference is 100 cm and your hip circumference is 38 in.
The belly size is about 1.37 in. This means the waist circumference is about 1.37 inches larger than the hip circumference.
FAQ
Where should I measure waist circumference?
The WHO STEPS protocol measures the waist midway between the lowest palpable rib and the top of the hip bone. Keep the tape level and snug without compressing the skin, and measure after a normal exhalation. Use the same protocol for repeat measurements.
Where should I measure hip circumference?
Measure around the widest part of your hips and buttocks. Keep the tape level all the way around your body. For the most consistent result, stand normally with your feet close together.
Is belly size the same as waist-to-hip ratio?
No. Belly size in this calculator is the difference between waist and hip circumference. Waist-to-hip ratio divides waist circumference by hip circumference. For example, a 36 in waist and 40 in hips gives a belly size of -4 in, but a waist-to-hip ratio of 0.9.
