Cake Pan Size Converter

Pick the recipe's pan and the one you have. You'll get the number to multiply every ingredient by so the batter comes out at the same depth, in inches or centimetres.

Recipe's panCommon sizes

Shape

Unit

Diameter

Your panCommon sizes

Shape

Unit

Length

Width

Eggs in the original recipe

Optional. Eggs are the one ingredient you can't measure by eye.

Multiply every ingredient by

× 2.33

Your pan has 755 cm² of base against the recipe's 324 cm² (117 vs 50 sq in). Use about 4.7 eggs; beat them and weigh out the fraction (a large egg is roughly 50 g out of its shell).

More batter in a bigger pan usually means a longer bake at the same temperature. Start checking at the original time and keep going in 5-minute steps.

Scale the full ingredient list by × 2.33 →

How pan conversion works

Batter fills a pan to a depth, so what matters is the base area. If your pan's base is 1.5 times larger, you need 1.5 times the batter to bake a cake of the same height.

Round: area = π × (diameter ÷ 2)²
Square: area = side × side
Rectangle or loaf: area = length × width

The scale factor is your pan's area divided by the recipe pan's area. Take an 8-inch round recipe into a 9×13-inch pan: 50.3 sq in becomes 117 sq in, so you multiply everything by about 2.33.

Common swaps

Recipe pan	Your pan	Multiply by
8" round	9" round	1.27
9" round	8" round	0.79
8" round	8" square	1.27
Two 9" rounds	9×13" rectangle	0.92
20 cm round	23 cm round	1.32
20 cm round	20 cm square	1.27

US, UK and Australian tin sizes

American recipes give pans in inches and British and Australian ones in centimetres. The sizes line up closely but not exactly: an 8-inch pan is 20.3 cm and a 9-inch pan is 22.9 cm. For most cakes that difference is small enough to ignore; for a tall or delicate bake, use the converter with the exact sizes.

Bake time and temperature

Keep the temperature the recipe gives and adjust the time. Deeper batter needs longer, and very deep batter can brown on top before the middle sets; a lower shelf or a loose sheet of foil helps. Shallower batter bakes faster, so start checking well before the recipe's time is up.

Once you have the factor, the recipe scaler multiplies the whole ingredient list for you.

Frequently asked questions

How do I convert a recipe to a different pan size?

Divide the area of your pan by the area of the recipe's pan, and multiply every ingredient by that number. A round pan's area is π × radius²; a square or rectangle is length × width. The converter does this for you and works in inches or centimetres.

Can I use a 9-inch pan instead of an 8-inch pan?

Yes, but a 9-inch round has about 27% more base area than an 8-inch, so the same batter bakes up thinner and faster. Either scale the recipe by about 1.27 to keep the same depth, or keep the recipe as it is and start checking earlier.

What size is a 20 cm cake tin in inches?

20 cm is about 7.9 inches, so UK and Australian recipes written for a 20 cm tin work in an 8-inch American pan with almost no change. A 23 cm tin is close to a 9-inch pan.

Do I need to change the baking time?

Usually. Batter that ends up deeper takes longer to cook through, and shallower batter cooks faster. Keep the oven temperature the same, start checking early, and use a skewer or the cake's spring-back to judge doneness.

What about eggs when the factor isn't a whole number?

Beat the eggs together and weigh out the fraction you need. The converter tells you roughly how many eggs to use.