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Cake Serving Calculator: Sizes and Cutting Layout
Count whole cake portions using your pan sizes and the cut size you choose. Compare round, square or rectangular tiers and inspect the layout before serving. The tool separates an area-based upper bound from slices that fit whole, with no account and no data sent to a server.
Every slice accounted for
No inputs sent. Nothing kept after closing unless you download a file.
Worked example
A 20 × 30 cm rectangular cake with no trimmed border fits 24 portions measuring 5 × 5 cm. An area quotient alone is not enough for a circle: curved edges leave pieces that the layout keeps as offcuts.
| Tier | Shape | Width (cm) | Length (cm) | Whole portions placed | Area upper bound | Uncut area (cm²) |
|---|---|---|---|---|---|---|
| Tier A | Round | 20 | 20 | 6 | 12 | 164.15927 |
| Tier B | Rectangle | 20 | 30 | 24 | 24 | 0 |
How to use it
Replace the example with your values and check units. Results update as you edit. Keep a scenario to compare, then export a file; this tool’s JSON can restore your inputs.
Worked example
A 20 × 30 cm rectangular cake with no trimmed border fits 24 portions measuring 5 × 5 cm. An area quotient alone is not enough for a circle: curved edges leave pieces that the layout keeps as offcuts.
Method and sources
Rectangles compare two grid orientations and keep the one with more whole portions. For circles, every corner of a portion must fit inside the usable radius; several grid offsets are tried. The area upper bound divides usable area by slice area. That number alone is not a workable cutting layout.
Sources checked October 28, 2026.
Starting values are a fictional example. The method and limits below describe what is actually calculated.
Who it is for, and limits
This is a geometry guide, not a nutrition table or a serving guarantee. Height, filling, supports and irregular cuts are not modeled. One tier is one cutting surface, not each cake layer. Confirm portion sizes with the baker and person serving.
Common questions
Is the area quotient a serving count?
Area gives a theoretical upper bound. The layout keeps whole portions that fit.
Can I add several tiers?
Each row is an independent cutting surface. Tier results are added.
Is the circular layout optimal?
The tool tries several grids and keeps the best found. It does not prove a global optimum.
Where do my inputs go?
They stay on this page. An explicit export keeps data in your chosen file; nothing is saved automatically.
Can I compare and restore a scenario?
Compare keeps up to three scenarios during this session. The JSON download lets you restore a scenario after closing.