Bakery windows carry labels such as "size 1" or "size 2". What those numbers mean stays unclear to most customers.
Where does the numbering come from?
The system rests on no formal standard.
It is a convention that settled in the trade over time.
The numbers generally indicate the diameter of the cake or the size of the tin used.
A small number means a small cake.
But even the direction is not universal; in some bakeries 1 is the smallest and in others the largest.
That ambiguity creates problems when ordering.
Two bakeries can differ by 30 to 40 percent in size under the same number.
Orders should therefore discuss diameter and servings rather than a number.
Diameter in centimetres is a clear measure; a number is not.
What are the diameter and weight equivalents?
The ranges in common use run as follows.
The smallest cakes are 16 to 18 centimetres across and weigh one to one and a half kilograms.
Medium cakes are 20 to 24 centimetres and weigh two to three kilograms.
Large cakes are 26 to 30 centimetres and weigh three and a half to five kilograms.
Larger than that is a special order: 32 centimetres and above.
Weight rises with the square of the diameter.
Double the diameter and the area quadruples; the weight rises roughly in proportion.
That is a frequent error in calculation.
Twice a twenty-centimetre cake is not forty centimetres but around twenty-eight.
| Diameter | Approximate weight | Small slices | Standard slices |
|---|---|---|---|
| 16 cm | 1-1.2 kg | 10-12 servings | 6-8 servings |
| 20 cm | 1.8-2.2 kg | 16-20 servings | 10-12 servings |
| 24 cm | 2.8-3.2 kg | 24-28 servings | 16-18 servings |
| 28 cm | 4-4.5 kg | 34-40 servings | 22-26 servings |
| 32 cm | 5.5-6 kg | 45-50 servings | 30-34 servings |
How are servings calculated?
That calculation depends on slice size and has no single answer.
A standard slice of cake weighs around 100 to 120 grams.
That measure is used for celebrations and birthdays.
Slices for a spread run 60 to 80 grams.
That measure is preferred for meetings and large gatherings.
Where the cake follows a meal the slice should be smaller; the guests are full already.
Where cake is the only thing served the slice should be larger.
The practical calculation: cake weight divided by slice weight.
A three-kilogram cake serves twenty-five at 120-gram slices.
The same cake serves thirty-seven at 80-gram slices.
That difference should always be discussed when ordering.
How do tiers change the calculation?
Cakes can be single or multi-tiered.
Tiers allow the same diameter to reach more people.
A two-tier cake weighs roughly twice a single tier.
But the slice height increases too, which allows the width to be reduced.
A tall slice provides enough volume even when cut narrow.
The calculation changes for three or more tiers; upper tiers are generally smaller in diameter.
For those cakes the servings of each tier are calculated separately and added.
On wedding cakes the top tier is often not cut, being kept or held as a symbol.
That belongs in the calculation too.
Filling between tiers adds weight but does not directly increase servings.
Does the shape affect the calculation?
Yes, and it gets overlooked.
A round cake covers less area than a square one of the same measurement.
A round cake twenty centimetres across has an area of 314 square centimetres.
A square cake twenty centimetres on a side has an area of 400.
The difference is 27 percent.
A square cake of the same measurement therefore serves roughly a quarter more people.
Rectangular cakes have an advantage in slicing too; cutting equal slices is easier.
On a round cake, slices near the centre are narrow and those near the edge wide.
Rectangular tray cakes are preferred for large gatherings.
A round cake is more classic in presentation.
What should be asked when ordering?
Five questions remove the ambiguity.
The first is diameter. "How many centimetres?" gives a far clearer answer than a number.
The second is weight, requested in kilograms.
The third is servings, asking which slice size the bakery based its figure on.
The fourth is the number of tiers and the height.
The fifth is how it arrives: sliced or whole, boxed or on a board.
With those five asked, a genuine comparison between two bakeries becomes possible.
Price comparison only becomes meaningful with that information.
Price per kilogram is the most accurate basis for comparison.
How are leftovers stored?
Over-ordering is common, which raises the question of storage.
Cream cakes keep two to three days in the fridge.
Fruit cakes keep a shorter time: two days.
Chocolate-coated cakes keep three to four days.
The cut face should not be left exposed; cling film or a covered container should be used.
Film should not touch the cream directly; cocktail sticks can support it.
Freezing is possible but limited; cream cakes weep when frozen.
Chocolate and ganache-based cakes freeze better.
Where a cake is frozen it should be sliced and wrapped individually so only what is needed gets thawed.
Thawing should be slow and in the fridge.
Fruit cakes and those set with gelatine should not be frozen; the structure breaks down entirely.
How do layers and filling affect the portion?
Two cakes of the same number can serve different numbers of people.
Height and the number of layers decide it.
A standard two-layer cake is around eight centimetres high.
Height reaches twelve centimetres in three-layer cakes.
A three-layer cake of the same diameter gives 40 to 50 percent more portions than a two-layer one.
The density of the filling matters too.
Rich cream and fruit fillings are more filling and the portion can shrink.
Portions stay larger in cakes with a light filling.
The number of layers and the total weight should be asked when ordering.
Calculating by weight is the most reliable method; 120 to 150 grams per head is a suitable measure.
Where the cake is served after a meal that figure can fall to 90 or 100 grams, since guests take less when they are already full.
