Resizing cake recipe

[WeAreTheHeroes]

Lordy - I've agreed to make a special cake and have a particular recipe, but (big but!) I'm going to need to make a bigger cake than the recipe makes, and possibly two different sized tiers... Can anyone please point in the direction of a conversion table to help me figure things out?

It's not just the amount of batter you'll need to adjust, but the cook time/temperature.
How big a difference are you talking about?

It might help to post the recipe. If it’s similar to something else that would be a good place to start.

Following as I’ve struggled with this as most recipes seem to be for small cakes. You will need a longer baking time. I used this Mary Berry recipe but in a round 10 inch tin. It needed a good hour though. I did it x2 to stack

You could try using this converter

I'm not posting the recipe, family are on here and they'll know it's me! Yes, I realise cooking times will be different too. I'm a fairly experienced baker, but don't want to mess up. There are lots of converters online so I was hoping someone could recommend one they'd used successfully.

I'd say it really depends on the type of cake you're baking. For example, some fruit cakes can take a couple of hours to cook, so if it was scaled up I might give it an extra half hour, depending on how much larger it is. And you might need to put some baking paper over the top of it to stop the outside burning while you try and get the inside cooked.
But a sponge cake, which usually takes 20-30 mins, might only take an extra 5 for a slightly scaled up cake. I'd suggest poking it with a cocktail stick to see if it comes out clean.

As a general rule of thumb I use 1 egg per 2" cake diameter, I bake 2 cakes to get the layers for each tier and I use a cake leveller to get them all the same height.

So example:
8" tier - bake 2 cakes, each with a 4 egg recipe.
10" tier - bake 2 cakes, each with a 5 egg recipe.

Just scale your other ingredients accordingly.

In terms of timing I go by look, feel and sound - I don't try to scale timings!

@FrangipaniBlue - that's really useful on the eggs to inches ratio. Yes, the baking time will need careful watching.

I've got some of the baking belts to go around tins and can double line the tins too.

Thanks everyone!

@Mustangsallyis - thank you! I remember her on GBBO.

This is maybe not what you want as you have your recipe, but this basic birthday cake recipe is great, I’ve used it many times, and it has a calculator where you enter tin size and number of layers and it’s all worked out for you. I’ve tried different sizes with it and has worked out.

charlotteslivelykitchen.com/birthday-cake-all-in-one-vanilla-sponge/

Always good to have something like that - thank you.

I made two out of the three cakes I need yesterday and have frozen them until I'm ready to decorate them. After all that I used a slightly bigger tin and after working out that the difference in volume was negligible didn't change the recipe. Seems to have worked perfectly - I used collars on the tin and used our convection oven instead of the fan oven.