Cake size calculator
Tell us how many people you are feeding and how the cake is being served. Most people over-order for a birthday and under-order when the cake is the only dessert — the difference between those two is nearly double.
These are standard portion conventions, not measurements from our own orders. Bakers cut slightly differently, so treat the result as a starting point and round up if your headcount is not final.
How many people does each size serve
Dessert portions are about 125 g each; a celebration slice cut after the candles is about 75 g. The last column shows why shape matters — the same weight in a square tin cuts into clean rectangles instead of losing servings to curved edges.
| Cake weight | As dessert | Celebration slice | Square, celebration |
|---|---|---|---|
| 500 g | 4 | 6–7 | 8 |
| 1 kg | 8 | 13 | 16 |
| 1.5 kg | 12 | 20 | 25 |
| 2 kg | 16 | 26 | 33 |
| 3 kg | 24 | 40 | 50 |
| 5 kg | 40 | 66 | 83 |
Seven things most people get wrong about cake
Double the diameter, and you get four times the cake
A round cake's area grows with the square of its radius, so a 12 inch round holds four times as much as a 6 inch — not twice. Even the step from 6 to 8 inches is a 1.8× jump. This is why sizing by inches goes wrong so often, and why Indian bakers quoting by the kilo are doing everyone a favour.
A square cake serves about a quarter more than a round one
Same weight, same recipe, more servings — because a square cuts into clean rectangles while a round loses portions to curved edge pieces. If you want the most servings for the money and the shape does not matter, order a square or a rectangle.
Height counts as much as width
Three layers at the same diameter is 50% more cake than two. Bakers usually quote servings against a standard cake height, so a taller build at the same width can quietly change how many people it feeds.
Tiers are a look, not a serving strategy
Guests do take a slightly smaller slice from a tall tiered cake, which stretches it by roughly 8–15% per kilo. But that is a rounding difference. Choose tiers because you want the height and the moment, not to feed more people — a single larger cake is cheaper per serving.
The fridge is for the frosting, not for the cake
Fresh cream, custard and cheese frostings genuinely need refrigeration. The sponge does not — it goes stale fastest just above freezing, because that is where starch retrogradation runs quickest. A plain or fondant-covered cake keeps better in a sealed box on the counter, and for longer storage freezing beats refrigerating outright.
Cold cake tastes flatter
Fat firms up and aromatic compounds stay put when cake is cold, so a slice straight from the fridge reads as dense and muted. Take it out 30 to 60 minutes before serving. This is the cheapest possible improvement to any cake.
There is a mathematically better way to cut a cake
In 1906 the scientist Francis Galton published a method in Nature for cake eaten over several days: instead of wedges, cut a straight strip through the middle, take that, then push the two halves back together. The cut faces stay pressed against each other and the cake dries out far less than a wedge-cut one.
Cake size questions
How much cake do I need for 20 people?
For a celebration slice cut after the candles, allow about 75 g per person — roughly 1.5 kg for 20 people. If the cake is the dessert course, allow about 125 g per person, which is about 2.5 kg for 20. A square cake of the same weight serves around 25% more people than a round one, because it cuts into clean rectangles with no curved edge pieces.
How many people does a 1 kg cake serve?
A 1 kg cake serves about 8 people as a dessert portion, or about 13 as a celebration slice cut after the candles. The same 1 kg in a square shape stretches further — closer to 16 celebration slices — because there is no waste at the edges.
Does the shape of the cake change how many people it serves?
Yes, and it is the most commonly missed factor. A square or rectangular cake cuts into even rectangles with nothing left over, while a round cake of the same weight loses servings to curved edge pieces. The usual convention is that a square yields around 25% more servings than a round cake of identical weight.
Do tiered cakes serve more people per kilogram?
Slightly, because guests take a smaller slice from a tall tiered cake than from a single round one. Allow roughly 8% more servings per kilogram for a two-tier cake and around 15% more for three tiers or higher. Tiers are usually chosen for how the cake looks rather than for the number of servings.
How long can a cream cake stay out of the fridge in Delhi?
In Delhi NCR summer heat, a fresh cream or whipped cream cake should not sit out of refrigeration for more than about two hours, and less on the hottest days. Fondant and ganache finishes hold their shape far better in heat, which is why they are the usual choice for outdoor functions and long parties.
Should I order extra cake?
If the headcount is not final, or you want people to take a piece home, add about 20% to the calculated weight. Bakers sell in half-kilogram steps, so the practical choice is usually to round up to the next half kilo.
Is a 12 inch cake twice as big as a 6 inch cake?
No — it is four times as big. A round cake's area grows with the square of its radius, so doubling the diameter quadruples the amount of cake. An 8 inch round holds about 1.8 times as much as a 6 inch, and a 10 inch holds about 2.8 times as much. This is the single most common mistake when sizing a cake by inches rather than by weight.
Should I keep cake in the fridge?
Refrigerate it for the frosting's safety, not for the cake's freshness. Fresh cream, custard and cheese-based frostings must be kept cold. But sponge goes stale fastest at fridge temperature — starch retrogradation runs quickest just above freezing — so a plain or fondant-covered cake keeps better in a sealed box at room temperature. If you need to store cake for more than a couple of days, freezing is better than refrigerating, because it skips past the temperature range where staling is quickest.
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