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ConversionscookingUnited States only

Baking Pan Size Converter

Converting a recipe between tin sizes and shapes. Scale by base area rather than diameter, and a round 20 cm tin is not equivalent to a square 20 cm one: the square holds about 27 percent more.

Also called: cake tin conversion, pan size converter.

Original tin
cm
cm
New tin
cm
cm
cm
Multiply the recipe by
1.27

Multiply every ingredient by 1.27. The original tin has 314.16 cm² of base and the new one 400 cm², a difference of 27.32%. Baking time follows batter depth rather than quantity, so a scaled recipe at the same depth bakes in about the same time.

Original base area
314.16
New base area
400
Difference in area
27.32
Original capacity
1,570.8
New capacity
2,000
Depth the batter will reach
3.93
On baking time
Baking time follows batter depth rather than quantity, so a scaled recipe at the same depth bakes in about the same time.
How this is calculated
Method and background

How this is calculated

Batter depth governs baking time, so keeping depth constant means scaling by base area. That is why a round 20 cm tin and a square 20 cm tin are not interchangeable: the square has 400 cm² against the round's 314, about 27 percent more. Scaling by diameter instead of area is the common error and produces a cake either overflowing or too shallow. Baking time changes with depth rather than quantity, so a scaled recipe at the same depth bakes in roughly the same time.

scale by base area, because batter depth is what governs baking time
A
Base area

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

a 20 cm round to a 20 cm square

Original tin
Round
Diameter or length
20 cm
Width, if rectangular
20 cm
New tin
Square
Diameter or length
20 cm
Width, if rectangular
20 cm
Tin depth
5 cm

Multiply the recipe by1.27

400/314.16, the 27 percent difference this page exists to show

Open this example

the same tin needs no scaling

Original tin
Round
Diameter or length
20 cm
Width, if rectangular
20 cm
New tin
Round
Diameter or length
20 cm
Width, if rectangular
20 cm
Tin depth
5 cm

Multiply the recipe by1

boundary

Open this example

Method and limits

What it assumes

  • The same batter depth in both tins.

What it deliberately does not model

  • A much deeper cake needs a lower temperature and longer time regardless of the scaling.
  • Loaf and bundt tins behave differently because of their heat paths.

Formula version 1.0.0 · definition 1.0.0 · United States · Report a problem with this calculator

Frequently asked questions

Can I use a 20 cm square tin instead of a 20 cm round one?
Not without scaling. The square holds about 27 percent more, so the same batter would be noticeably shallower and bake faster.
Does baking time change when I scale up?
Barely, if the depth stays the same. Time follows depth, not quantity, which is why a wider tin at the same depth bakes in roughly the same time.