Baking Pan Size Converter

How to use this calculator

Choose the shape of the pan the recipe was written for and the pan you plan to use. For a round pan, enter the diameter; for a square pan, the side; for a rectangular pan, the length and width. Measure across the top inside edge. The scale factor tells you how much to multiply every ingredient by so the batter is the same depth as the original — use the recipe scaler to apply it to the whole ingredient list.

You can also work the other way: enter the original pan and a factor (for example 1 if you do not want to change the recipe) and the size of the other pan that holds the same batter is calculated — handy for finding which square pan replaces an 8-inch round.

The formula

Round: A = π d² / 4

Square: A = a²

Rectangle: A = a × b

k = A_new / A_original

a₁: original pan: diameter, side or length
b₁: original pan: width
A₁: original pan area
a₂: new pan: diameter, side or length
b₂: new pan: width
A₂: new pan area
k: scale the recipe by

Worked example

A cake recipe is written for one 9-inch round pan. You want to bake it in a 9 × 13 in rectangular pan.

Round pan area = π × 9² ÷ 4 = 63.6 in².
Rectangular pan area = 13 × 9 = 117 in².
Scale factor = 117 ÷ 63.6 = 1.84.

Make about 1¾–2 times the recipe for the 9×13 pan; doubling and filling slightly less deep works well.

Common pan areas

Pan	Area
8 in round	50 in²
9 in round	64 in²
8 × 8 in square	64 in²
9 × 9 in square	81 in²
11 × 7 in	77 in²
13 × 9 in	117 in²
Half sheet, 18 × 13 in	234 in²

A 9-inch round and an 8-inch square hold almost exactly the same batter.

Assumptions and limits

Both pans are filled to the same depth with straight sides. Pans with sloped sides hold a little less than their top dimensions suggest.
Baking time depends on batter depth rather than volume: same depth, similar time; deeper batter needs a lower temperature and longer bake.

Frequently asked questions

Can I bake a 9×13 recipe in two 9-inch rounds?

Yes. Two 9-inch rounds total 127 in², slightly more than 117 in² for a 9×13, so the layers will be a little thinner and bake a few minutes faster.

What can I use instead of an 8-inch square pan?

A 9-inch round (64 in²) is the closest match. An 11 × 7 in pan (77 in²) works with slightly thinner results.

How do I adjust the baking time for a different pan?

Keep the temperature and start checking 5–10 minutes early for a shallower pan; for a deeper pan, reduce the temperature by 25 °F and bake longer.