Being new in the #kitchen was not sure how much filling I needed to fill a 9 inch pie crust pan, Could #mathematics solve the problem? A pie pan is sort of a frustrum (cut off cone). We needed the volume of a pie pan, so we used the formula: V = ((3.14*h)/3)(R^2 + Rr + r^2) or V = ((3.14*1)/3)((4.5 * 4.5) + (4.5 * 3.5) + (3.5*3.5)). That equates to about 50 square inches or about 3.5 cups (50.5*0.0693=3.49965 ). Off to the store.