Pricing
Cake serving size chart: how many people does each size serve?
Serving counts for round and square tins from 6 to 12 inches, at both party and finger portion sizes, with the geometry they come from and the assumptions that break them.
the ibakepro team ·
Every serving chart in the trade is the same division: the area of the top of the cake, divided by the area of one portion. Once you know that, you can build the chart for any tin you own and, more usefully, you can tell when someone else's chart is answering a different question from yours.
Servings = tin area / portion footprint area
A round tin's area is pi times the radius squared. A square tin's area is the side times itself. Portions are cut the full height of the cake, so height does not enter the division. It decides how much cake is in each portion, which is a separate problem covered further down.
The two portion sizes
Two conventions are in common use, and they differ by a factor of two.
- A party portion is 1 inch by 2 inches (2.5 cm by 5 cm), so 2 square inches (about 13 sq cm) of footprint. This is the dessert-sized slice most people picture at a birthday.
- A finger portion, also called a coffee portion, is 1 inch by 1 inch (2.5 cm by 2.5 cm), so 1 square inch (about 6.5 sq cm). This is the slice handed round on a napkin at a wedding or a wake.
Both charts below assume a standard two-layer cake of roughly 4 inches (10 cm) finished height, which is what the conventional numbers were built on. Counts are rounded down, because you cannot serve four fifths of a slice.
Round tins
| Tin | Top area | Party portions | Finger portions |
|---|---|---|---|
| 6 in / 15 cm | 28.3 sq in | 14 | 28 |
| 8 in / 20 cm | 50.3 sq in | 25 | 50 |
| 10 in / 25 cm | 78.5 sq in | 39 | 78 |
| 12 in / 30 cm | 113.1 sq in | 56 | 113 |
Square tins
| Tin | Top area | Party portions | Finger portions |
|---|---|---|---|
| 6 in / 15 cm | 36 sq in | 18 | 36 |
| 8 in / 20 cm | 64 sq in | 32 | 64 |
| 10 in / 25 cm | 100 sq in | 50 | 100 |
| 12 in / 30 cm | 144 sq in | 72 | 144 |
A square tin serves about 27% more than a round tin of the same nominal size, every time, because a square of side d has area d squared and a circle of diameter d has area 0.785 times d squared. Four divided by pi is 1.27, and that ratio holds at every size on the chart. It is also why a customer comparing your round quote against someone else's square quote is not comparing like with like.
For a tiered cake, add the tiers. A 6, 8 and 10 inch (15, 20 and 25 cm) stack is 14 plus 25 plus 39, so 78 party portions, or 156 finger portions.
Trap one: the factor of two
The single most common quoting failure is two people using different portion conventions and neither saying which.
If a customer has been told a 10 inch (25 cm) tier gives 78 servings and you tell them it gives 39, you are both right and the conversation is about to go badly. Write the portion size on the quote, in words and in dimensions, every time. UK market conventions and what customers there assume is included are covered in pricing celebration cakes in the UK market.
Trap two: height changes the cake, not the count
Bake a tier at 3 inches (7.5 cm) instead of 4 (10 cm) and the geometry above is unchanged, because the footprint is unchanged. What changes is that each of those portions contains 25% less cake. The count on the chart still holds and the chart is still over-promising, because the portion the chart intended was 25% larger than the one you are handing out.
Tall cakes run the other way. A barrel or extended-height tier at 6 inches (15 cm) holds 1.5 times the volume of a 4 inch (10 cm) tier, and a full-height slice of it is too much cake for one person. Cut it into two half-height slices and an 8 inch (20 cm) barrel gives 37 party portions rather than 25.
Trap three: geometry is not the cut
The chart is the theoretical maximum. Real cutting loses to the first slice, to the person who cuts generously and to whatever the venue does with a round cake, which is usually concentric rings rather than a grid.
Quote the chart number and treat it as a ceiling rather than a promise. If the count matters, which at a wedding it does, size up a tier or add a plain cutting slab rather than defending the last four servings of a chart.
How the count drives your quote
Serving count is the unit customers compare on, so it is worth being clear about what it does and does not do to your price.
It does not change your cost. A 10 inch (25 cm) tier costs the same to make whether you describe it as 39 servings or 78. So if that cake costs 120 to make and you want a 45% margin, the price is 120 divided by 0.55, which is 218.18, whichever convention you quote in.
What changes is the rate. Divide 218.18 by 39 party portions and your rate is 5.59 a portion. Divide it by 78 finger portions and the rate is 2.80. Same cake, same price, two rates that look nothing like each other.
That is the whole argument for a published rate carrying its convention. It is also the argument for setting the rate from your costs first and checking the per-portion figure afterwards, rather than adopting a per-portion rate you saw somewhere and hoping it covers the cake.
Before you quote a serving count
- Which portion size, stated in dimensions, on the quote
- Your actual finished tier height, against the chart's assumption
- Round or square, because the same nominal size differs by 27%
- Whether a barrel tier is being cut once or twice
- Whether the count is a ceiling or something you have promised
Serving counts belong to the size, not to the order, which is why they are worth storing once. In ibakepro a size ladder carries dimensions, and portions and labour scale as separate lanes, so a bigger tier can serve more people without claiming it takes proportionally longer to decorate. Your finished bake height and the venue's knife sit between the chart and the plate, and both are yours to check. Product builder and variants covers how sizes and their ladders are set up.