Baking pan size conversion chart (with the area math)

To swap baking pans, compare their area, not their name. Two pans of the same depth and the same area hold the same batter and bake in about the same time.

The most useful fact: an 8-inch square (64 sq in) and a 9-inch round (about 63.6 sq in) are almost identical. King Arthur Baking treats them as interchangeable.

How to work out pan area

• Square or rectangle: length × width. A 9 × 13 pan is 117 sq in.
• Round: π × radius × radius. The radius is half the diameter. A 9-inch round: 3.1416 × 4.5 × 4.5 = 63.6 sq in.

Measure across the top inside edge, not the outside rim.

Pan area chart

Pan	Area
8-inch round	50.3 sq in
9-inch round	63.6 sq in
10-inch round	78.5 sq in
8-inch square	64 sq in
9-inch square	81 sq in
7 × 11 rectangle	77 sq in
9 × 13 rectangle	117 sq in
10 × 15 jelly roll	150 sq in
13 × 18 rimmed sheet	234 sq in
8 1/2 × 4 1/2 loaf	38.3 sq in
9 × 5 loaf	45 sq in

Rimmed sheets and loaf pans are much shallower or deeper than cake pans, so area alone is a rough guide for those.

Common swaps and their scale factors

The scale factor is new area ÷ old area. Multiply every ingredient by it.

From	To	Factor
8-inch square	9-inch round	0.99 (same)
8-inch square	9-inch square	1.27
8-inch round	9-inch round	1.27
9-inch square	9 × 13	1.44
8-inch square	9 × 13	1.83
9-inch round	9 × 13	1.84
9 × 13	10 × 15	1.28
9 × 13	13 × 18	2.00
8 1/2 × 4 1/2 loaf	9 × 5 loaf	1.18

A 13 × 18 sheet is exactly twice a 9 × 13: 234 ÷ 117 = 2.

Splitting a 9 × 13 into layers

A 9 × 13 sheet cake recipe makes 117 sq in of cake. Two layer pans give:

• Two 9-inch rounds: 2 × 63.6 = 127.2 sq in, about 9% more room than the 9 × 13. The layers come out slightly thinner. King Arthur says two 9-inch rounds offer about 10% more space.
• Two 8-inch rounds: 2 × 50.3 = 100.5 sq in, about 14% less room. The layers are thicker and can overflow if the pans aren't deep.

So a 9 × 13 recipe is a good fit for two 9-inch layers.

What King Arthur recommends for a 9-inch square recipe

From King Arthur Baking's pan guide:

• To fill a 9 × 13, increase the ingredients by 50%. The pan is about 45% larger.
• An 11 × 7 pan (77 sq in) works as is.
• An 8-inch square or 9-inch round (64 sq in) is about 20% smaller. Bars come out thicker, and cakes may overflow.

Worked example: brownies from 8 × 8 to 9 × 13

An 8-inch square brownie recipe uses:

• 1/2 cup (113 g) butter
• 1 cup (198 g) sugar
• 2 large eggs
• 1/2 cup (60 g) flour
• 1/3 cup (28 g) cocoa

Factor: 117 ÷ 64 = 1.83.

• Butter: 113 × 1.83 = 207 g.
• Sugar: 198 × 1.83 = 362 g.
• Eggs: 2 × 1.83 = 3.66 eggs. Use 3 eggs plus about 33 g of a fourth, beaten. King Arthur lists a large egg as 50 g, so 3.66 eggs ≈ 183 g.
• Flour: 60 × 1.83 = 110 g.
• Cocoa: 28 × 1.83 = 51 g.

Many bakers would just double the recipe for a 9 × 13 and bake slightly thicker brownies. That's a factor of 2 instead of 1.83, about 9% more batter per square inch. It works, but expect a longer bake.

The recipe scaler does this for a whole pasted list, including the grams in parentheses, and rewrites awkward amounts like 0.91 cup as cups plus spoons.

Baking time after a pan swap

• Same depth, different size: time stays roughly the same. Start checking at the original time.
• Deeper batter: more time. The center sets last.
• Shallower batter: less time. Check early.
• Bundt pans: King Arthur says a 10-cup Bundt needs about 30% more time than the same batter in a 9 × 13.
• Glass or stoneware: may need slightly longer, possibly at a lower temperature, according to the same guide.

Use cake pans about 2 inches deep. King Arthur recommends 2-inch-deep pans for cakes. Shallower pans can work for bars.

For oven settings, see the oven temperature conversion chart.