How to use the cake servings calculator
- Pick the pan shape: round, square or rectangle, and enter its size in inches.
- Enter the number of equal pans. For layers cut together as a stack, leave it at 1.
- Enter the area of one slice in square inches. A slice 1 inch wide and 2 inches long is 2 square inches.
- Read the number of servings, the pan area and the area left over.
Formula
Round pan area = pi x (diameter / 2)^2
Square pan area = side x side Rectangle area = length x width
Servings = whole slices of the slice area in the total pan area, rounded down
Pi is about 3.14159. The tool divides area and does not draw a cutting pattern.
An 8 inch round with 2 square inch slices
An 8 inch round pan has an area of 3.14159 x 4^2 = 50.27 square inches. Dividing by 2 gives 25.13 slices, so 25 servings, with 0.27 square inches left over.
A 9 inch square pan is 81 square inches, which gives 40 slices of 2 square inches. A 13 by 9 inch pan is 117 square inches and gives 58. Two 8 inch rounds make 100.53 square inches and 50 slices. A larger slice of 1.5 square inches would give 33 slices from one 8 inch round.
Area is a guide, not a cutting plan
Dividing area is a good estimate for a rectangular or square pan cut in a grid. A round cake cannot be cut into identical small rectangles without waste, so the real count may be a little lower, and wedge cuts differ again. The tool rounds down to be cautious, and it shows the area left over so you can see how much slack there is.
Slice size is your choice. A dessert slice can be smaller than a slice served alone, and an event with other desserts may call for smaller slices. Pick the area that matches how you plan to serve.
Planning for a crowd
To change a recipe for a different pan, use the baking pan size converter, which compares pan areas and gives a scaling multiplier. For planning food and drink at a party, see the party food and drink calculator. The circle calculator gives more geometry for round shapes.
For measurements in the kitchen, the cooking measurement converter converts cups, ounces and grams.
Assumptions and limits
- Servings equal the pan area divided by the slice area, rounded down.
- All pans are the same size when more than one is entered.
- Cake height, tiers stacked on one another and decoration are not modeled.
- The slice size is your own choice.
Frequently asked questions
How many servings are in an 8 inch round cake?
With 2 square inch slices, an 8 inch round gives 25 servings, because its area is 50.27 square inches.
How do I calculate cake servings from pan size?
Work out the pan area, then divide by the area of one slice and round down. A 9 inch square is 81 square inches, so 40 slices of 2 square inches.
Why does the tool round down?
A partial slice is not a serving, and rounding down avoids promising more slices than you can cut.
Does a taller cake give more servings?
Not in this arithmetic. Height changes how much each slice holds, but the number of slices depends on the top area and the slice size you choose.