Now you can find out if your derriere is perfect thanks to a mathematical formula devised by British researchers. "The perfect female derriere has firmness to the touch and a resilience that prevents undue wobble or bounce, yet looks soft with flawless skin," Dr. David Holmes, a psychology lecturer at Manchester Metropolitan University, told *The New York Post*.

Holmes offers this math formula that will tell you for sure: (S+C) x (B+F) / (T-V)

Or put another way:

(Shape + Circularity) x (Bounciness + Firmness) / (Texture - Vertical Ratio Symmetry).

First, you have to assess the assets. Use a scale of 1 to 20 with 1 being the worst and 20 the best in the following categories described by Holmes:

- S = overall shape (a ripe peach being just about right)
- C = circularity (rounder is better)
- B = bounciness (less wobble is preferred)
- F = firmness (too much push to that cushion loses points)
- T = skin texture (no cellulite)
- V = Calculate the ratio of your waist to your hips.

How to do this: Use a measuring tape to determine your waist and hip measurements. Measure your hip circumference at it's widest part, and measure your waist circumference at the belly button or just above it. Pull out your calculator and divide the waist circumference by the hip circumference or use an online waist-to-hip ratio calculator to run the numbers. Then do the math, inserting your numbers in place of the letters in the formula above. A perfect score is 80.