Is it the depth of a cake or its overall volume that dictates cooking time?

[Closetlibrarian]

I'm trying to work out how long to cook a cake that I'm cooking in a different pan to the recipe. Recipe calls for a 20cm round tin. I've calculated the volume of the mixture (I measured it when I put it in the round pan!) and now I need to make two additional cakes, using the same recipe, but in loaf tins. This is the trick - they need to be the same height as the cake in the round tin (I'm using them to make up the different parts of a birthday cake I'm making).

So, I've worked out how much I need to increase the quantities of the recipe. What I'm not sure of is how to adapt the baking time. The loaf tin versions will be the same height, but slightly smaller overall volume (about 15% less). Do I reduce the cooking time for the loaf versions by 15% also?

I assume it's by volume not height, but just stick a toothpick in it and if it comes out clean it's cooked. No need for maths

Usually depth, you can have a very thin wide cake that doesn't require much cooking but a deep cake like a loaf cake will take a long while to cook as it's very deep

A Swiss role takes about 10 minutes. That same mixture, even in muffin tins, would take longer than 10 minutes. So I think depth is a big factor in cooking time.

Depth / surface area definitely. I'd add 10 mins then check with a skewer