Two cake layers go into the oven together, but one is much thicker. Eyeballing the bowls seemed quick until the thinner layer finished first. Weighing the finished mixture can make equal portions easier to achieve without changing the recipe.
Before mixing, weigh the clean, empty bowl and record that number. Include only the bowl: a whisk left inside during one measurement changes the comparison. Check that the scale can safely hold the combined weight of the bowl and ingredients.
Subtract the container, then divide the mixture
Suppose the empty bowl weighs 620 grams and the bowl with finished batter weighs 1,520 grams. The mixture weighs 900 grams. For two identical tins, the starting target is 450 grams per tin. These are illustrative numbers, not a cake recipe.
Put the first prepared tin on the scale and tare it before adding batter. Repeat with the second tin. Use a flexible spatula to collect the mixture left on the bowl, then distribute the remainder as evenly as practical.
Do not spend so long chasing the last gram that an aerated mixture sits unnecessarily or loses volume through repeated stirring. The purpose is a useful division, not a laboratory contest.
Equal weight assumes comparable tins
Two different diameters will not produce the same depth from equal portions. A deep tin and a shallow sandwich tin also have different capacity limits. If you are changing the recipe’s tin arrangement, work out the appropriate capacity and baking approach before dividing the batter.
Smooth each surface gently and compare the depth visually. Confirm that both tins have the preparation the recipe requires and that neither is overfilled.
Weighing solves the portioning question; it does not guarantee identical baking. Position, tin material and oven behaviour can still affect the layers. Check each cake for the recipe’s signs of doneness instead of removing both automatically when only one is ready. Keep the empty-bowl weight in your baking notes if you regularly use the same bowl.