๐ Cake Slicing Calculator
A guide for cutting a round cake, pizza, or similar food into even portions.
Enter a round cake's (or pizza's, or any circular food's) diameter and how many equal slices you want, to calculate the central angle, arc length, and area per slice. Handy for cutting even portions.
How to use
- Enter the cake's diameter (cm).
- Enter how many slices you want.
- The angle, arc length, and area per slice are calculated automatically.
How the calculation works
Work out the angle, outer edge length and area of each slice when cutting a round cake or pizza into equal pieces. Angle = 360ยฐ รท number of slices Outer edge length (arc) = ฯ ร diameter รท number of slices Area per slice = ฯ ร (diameter รท 2)ยฒ รท number of slices Measure the arc length around the side of the cake with a ruler or tape, mark equal intervals, then cut towards the centre for evenly sized slices.
Worked example
An 18 cm cake cut into 8 Angle 45ยฐ, about 7.07 cm apart around the edge, about 31.8 cmยฒ per slice In Japan, cake sizes are given as gล, where 1 gล is 3 cm (size 4 is 12 cm, size 5 is 15 cm, size 6 is 18 cm). Odd numbers of slices (5 or 7) are hard to judge by eye, so marking the edge by arc length helps.
Things to be aware of
- For 6 or 8 slices, cut in half first and then divide each half.
- Warm the knife and wipe it after every cut for clean edges.
- For a square cake, divide the length and width instead.
FAQ
How is the central angle calculated?
It's the full circle's 360ยฐ divided by the number of slices (360ยฐ รท slices) โ the angle each slice spans as seen from the cake's center.
What is arc length?
The length of the outer edge (the side of the cake) for one slice, calculated as the circumference (ฯ ร diameter) divided by the number of slices. It's a useful guide for marking even intervals around the edge.
How do I use this to actually cut the cake?
Use the central angle like a protractor from the center, or measure the arc length along the outer edge to mark evenly spaced points before cutting, for more even slices.