Pan size converter
A recipe written for one tin rarely fits another, and guessing is how cakes overflow or bake flat. This converter compares the base area of both pans and gives you the factor to multiply every ingredient by.
How it works
Why area and not volume
For most cakes and tarts you want to keep the batter depth the same and change the footprint, so base area is the right comparison. Keeping depth constant also keeps the baking time close to the original.
Adjusting the bake
Same depth means roughly the same time, but a much larger pan still needs a few extra minutes and a smaller one a few less. Keep the temperature as written and judge doneness the way the recipe tells you to, not by the clock.
Where scaling breaks down
Below about 0.5× or above 2× the results drift: egg quantities stop landing on whole eggs, and very thin or very deep batters bake differently. Past that range, look for a recipe written for the size you actually have.
Frequently asked questions
Can I convert a round recipe to a rectangular pan?
Yes — the calculator compares areas whatever the shapes. A 20 cm round pan and a 18×18 cm square pan are within a few percent of each other, so many recipes swap between them with no change at all.
What about eggs?
Weigh them. A large egg is about 50 g without the shell, so a factor of 1.4 on three eggs means 210 g of egg, which you can measure exactly rather than rounding to four.
Does this work for tartlets?
For the filling, yes. Shortcrust is usually rolled to a set thickness, so scale the pastry by the total surface you need to line rather than by this factor.
Learn this properly
A calculator gets the numbers right. Getting the result right is a craft — our chefs teach it step by step, with feedback on your own bakes.
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