Can someone help me work out a cake recipe amount please?

[Badburyrings]

Apologies in advance for the very dim question. I have a recipe for a chocolate cake and it works brilliantly but the amounts are for two 8" tins (so two layers).

I want to make a 12" cake with three layers and only have one tin. So I need to do the amounts 3 times and cook each one separately. The ingredients list is as follows, can anyone work out what I need to do to the amounts weight wise to achieve this? Or should I just use the original amount and chuck it in 12" tin?

Ingredients

1 ¾ cup (250g) all-purpose flour
⅔ cup (56g) cocoa powder (I prefer this Dutch cocoa or this one)
NOTE: if you prefer natural cocoa, my preferences are Ghirardelli 100% Cocoa and Hershey's Unsweetened
1 teaspoon baking powder
1 teaspoon baking soda
1 cup (200g) granulated sugar
½ cup (110g) packed light brown sugar
¾ teaspoon salt
2 large eggs
½ cup (120ml) vegetable oil (I prefer sunflower oil)
¾ cup (180ml) full fat sour cream
1 teaspoon (5ml) pure vanilla extract

1 cup (240ml) hot coffee

'Tough Cookie' different sized tins'
Might help. Sorry, can't get a link to work.

Are you wanting them to be the same depth as the 8” layers? So say it normally makes a 1” layer for the 8”, are you wanting the same as that?

could this help @Badburyrings

https://whatsarahbakes.com/baking-secrets/how-to-adjust-a-cake-recipe-to-fit-any-size-cake-pan-or-tin-easily/

I'd just do 1 and 1/2 mix for each cake.

Forget that just realised the original was for 2 layers. I would do the original for one layer, it might be deeper but that probably won't matter.

Yes, if the original did one layer I would just half the original and add that. But I only have one tin. Maybe I should just do that anyhow and only put half in the tin and cook and then add another half and cook. But I still need the right amount for the third one. It's making my brain ache.. maybe I should just go and buy another tin!

actually, this looks more useful?

https://keikos-cake.com/panconversion.html

That's really good @beetr00 - I have the conversion factor now, I just need to work out the amounts.

Two 8” cakes are about 90% the volume of one 12” cake. So it’s not far wrong to take the total amount you use for your 2 layer 8” cake and use that for each of the 12” layers.

1 ¾ cup (250g) all-purpose flour 282g
⅔ cup (56g) cocoa powder (I prefer this Dutch cocoa or this one) 63g
NOTE: if you prefer natural cocoa, my preferences are Ghirardelli 100% Cocoa and Hershey's Unsweetened
1 teaspoon baking powder 1&1/8th
1 teaspoon baking soda 1&1/8th
1 cup (200g) granulated sugar 225g
½ cup (110g) packed light brown sugar 124g
¾ teaspoon salt 4/5th tsp
2 large eggs 2 1/4
½ cup (120ml) vegetable oil (I prefer sunflower oil) 135ml
¾ cup (180ml) full fat sour cream 202.5ml
1 teaspoon (5ml) pure vanilla extract 5.6ml

1 cup (240ml) hot coffee 270ml

The amounts in bold are the correct amounts for a 12” layer the same thickness as one of the 8” layers you normally do.

The way I work it out is to get the volume of a cylinder. So the volume of a cylinder (your layers) 8” in diameter x 1” high is 50.27 and the volume of a cylinder 12” in diameter and the same height is 113.10. 113.10/50.27=2.25 (roughly). So you times your 8” amounts by 2.25 to get your 12” amounts. However, in this case, you halve the amounts of the 8” first because you want them the same thickness as what half the mixture makes in the original recipe.

This method served me well as a cake maker.

Oh my god you are AMAZING! thank you so much! am going to give it a go this afternoon.

This sounds like a maths problem for GCSE!

Well done to @HÆLTHEPAIN for so diligently working it out

@Badburyrings can we see the finish cake it sounds amazing!