Cake Pan Conversion Calculator

About this calculator

Scaling a cake recipe between pan sizes or shapes is based on surface area rather than volume alone, since batter depth needs to stay roughly consistent for the recipe's original bake time and temperature to still apply reasonably well. The scaling factor is: new pan area ÷ original pan area, calculated with πr² for round pans or length × width for rectangular ones, and every ingredient quantity in the recipe is multiplied by that same factor.

Home bakers and professional pastry cooks use this calculation whenever a recipe is written for a pan they don't own — swapping a 20 cm round pan for a 9×13 inch rectangular one, for instance — because scaling by area (rather than guessing) keeps the batter at roughly its original depth, so the bake time only needs a modest adjustment rather than a complete recalculation. A significant depth change still shifts bake time noticeably, so the result is usually paired with a shortened or lengthened baking time and a doneness check rather than an unchanged one.

This calculator takes your current pan and the new pan you're switching to, and returns the recipe scaling factor to apply to every ingredient.