Whatever the celebration your cake is for, you want to make sure that you will have enough for all of your guests to have a piece! The guide below calculates how big your cake needs to be depending on how many portions you are going to need from it.
Please bear in mind that this is a rough guide only as it depends on the person who is cutting the cake.The best way to get the maximum amount of portions from your cake is to cut it like a chess board into squares. This will give you a longer thinner slice of cake which is perfect as a portion, but can also be cut in half to create double the amount, ideal as a party favour.
Novelty shaped cakes are tricky to work out portion sizes but I will always try to work out an approximate number for you.
Portion guide for fruit cakes
Approx portions
Size Round
13 cm (5in) 16
15cm (6in) 25
18cm (7in) 36
20cm (8in) 49
23cm (9in) 64
25cm (10in) 81
Portion guide for sponge cakes
Approx portions
Size Round
13 cm (5in) 8
15cm (6in) 12
18cm (7in) 18
20cm (8in) 24
23cm (9in) 32
25cm (10in) 42