How much cake mix for a bigger tin?

[yaela123]

I love and am usually quite good at baking, but can never get my head around the maths side of it so usually just double/triple/whatever and hope for the best. Unfortunately, I won't have any second chances with this so it needs to be right.

I have to make a cake for someone's birthday and want to use a rectangular tin which is 11.5" x 9" at the base and 12.5" x 10.5" (It kinda goes out iyswim)

The recipe is for a 7" round tin.

Can anyone help me work out how much I would need to times each ingredient by to get the right quantity?

Thank you so much and in return I can send you some virtual cake

Do you want the cake to come out the same height as the original 7" recipe?

If you want it the same depth as the original the way to do it is by surface area

So the original cake was 7" round.
Its area was 3.5 x 3.5 x π = 38.5 square inches

Your new tin is 12 x 10" (average), area is 120 square inches

120 / 38.5 = 3.1

I'd triple the recipe

(I have just worked out a 1 + 1/6 recipe for a pastel des tres leches for dd's class Mexican day 🙄)

Well the original tin is about 38sqcm. On average, the new tin is about 12x10=120sqcm, so I would do 3 times the mixture.

A 7" round tin holds roughly 2 pints of cake mix. The measurements you give for the rectangular tin seem to average to roughly an 11" square tin, looking at the site below, apparently this would need about 8 pints, so that would mean multiplying everything by 4. Is it a ginormous tin?! www.hintsandthings.co.uk/kitchen/tins.htm

m.joyofbaking.com/PanSizes.html

food52.com/blog/13239-how-to-make-your-baking-recipe-fit-your-pan-size

Thank you everyone! I think I will triple the recipe, and have bookmarked the links for next time