Pan Size Conversion Calculator
Depth sets the bake time, not area.
Work out Pan Size Conversion. Depth sets the bake time, not area. States the assumption instead of hiding it.
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20 cm round → 23 cm round · 415 cm² against 314 cm²
Pans compare by area, not by nominal size. A 23 cm round holds about a third more than a 20 cm one, and a 20 cm square holds about a quarter more than a 20 cm round — which is why swapping them by eye ruins the depth. Depth, not area, sets the baking time. Scale the recipe to the new area and the depth is unchanged, so the original time and temperature carry over. Keep the batter and change the pan, and the time has to move with the depth. Deeper batter also wants a cooler oven. Left at the original temperature, the outside sets and browns long before the centre is cooked, which is the usual cause of a sunken middle in a scaled-up cake.
How the Pan Size Conversion Calculator works
Swap between round, square and rectangular tins by area, either scaling the recipe to keep the depth or keeping the batter and adjusting the time and temperature for the depth that results.
Also known as: 20cm round to 23cm round cake tin · can i use a square tin instead of round · cake tin substitution chart · baking time for a different tin
Not medical advice. This calculator gives a general estimate, not medical advice. It cannot account for your individual health, medical history, or medication. Talk to a qualified healthcare professional before acting on any result.
Frequently asked questions
How do I substitute one cake tin for another?
Compare areas, not nominal sizes. A 23 cm round holds about a third more than a 20 cm one, and a 20 cm square holds about a quarter more than a 20 cm round.
Should I scale the recipe or change the time?
Scaling to the new area keeps the depth, so the original time and temperature carry over unchanged. Keeping the batter changes the depth, and the time has to follow.
Why does a deeper cake need a cooler oven?
Because heat has further to travel to the centre. At the original temperature the outside sets and browns long before the middle cooks — the usual cause of a sunken centre.
Is a square tin bigger than a round one of the same size?
Yes, by about 27%. A 20 cm square is 400 cm² against a 20 cm round's 314 cm², which is why a straight swap leaves a shallow, overbaked cake.
How full should a tin be?
About two thirds for most cakes. Fuller than about 85% risks overflowing as the batter rises, and much less than half gives a thin, dry result.
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