The formula to calculate the Belly Size (BS) is:
\[ BS = WC - HC \]
Where:
Let's say the waist circumference (WC) is 40 inches, and the hip circumference (HC) is 35 inches. Using the formula:
\[ BS = 40 - 35 = 5 \, \text{inches} \]
So, the belly size is 5 inches.