Baking techniques

Cake Pan Size Conversions

Use pan area to scale a cake recipe from rounds to squares to a 9x13, adjust batter depth and bake time, and avoid the overflow or dry edges that follow guessing.

Recipes are written for a specific pan, and switching to a different size changes how deep the batter sits, how fast heat reaches the center and whether the batter fits at all. The good news is that a little arithmetic with pan areas gets you most of the way, and a few rules about depth and temperature cover the rest.

This guide gives the areas of common pans, shows how to calculate a scaling factor, and explains how to adjust oven temperature and timing when the batter ends up thicker or thinner than the original.

Key points

Compare pans by area: multiply length by width for rectangles, and 3.14 times the radius squared for rounds.
Divide the new pan's area by the original pan's area to get the factor for scaling the recipe.
Fill cake pans about one-half to two-thirds full to leave room for rise.
Shallower batter bakes faster; deeper batter needs a lower temperature and more time.
Always check doneness by touch and a toothpick rather than the original recipe's timing.

Common pan areas

Areas are rounded. Metric sizes are the usual equivalents sold, so small differences are normal. The numbers let you see at a glance which pans are interchangeable.

15 cm (6 inch) round: about 28 sq in (177 sq cm)
20 cm (8 inch) round: about 50 sq in (314 sq cm)
23 cm (9 inch) round: about 64 sq in (415 sq cm)
25 cm (10 inch) round: about 79 sq in (490 sq cm)
20 cm (8 inch) square: 64 sq in (400 sq cm)
23 cm (9 inch) square: 81 sq in (530 sq cm)
23 x 33 cm (9 x 13 inch) rectangle: 117 sq in (759 sq cm)
Two 20 cm (8 inch) rounds: about 100 sq in; two 23 cm (9 inch) rounds: about 127 sq in

Calculating a scaling factor

Divide the area of the pan you want to use by the area of the pan in the recipe. For example, a cake written for a 9 x 13 inch pan (117 sq in) baked in two 8 inch rounds (about 100 sq in) needs a factor of 100 / 117, or about 0.86. Multiply every ingredient by 0.86, which is easiest with a kitchen scale.

Going the other way, scaling an 8 inch round recipe down to a 6 inch round gives 28 / 50, or about 0.56. Many bakers simply halve the recipe in that case and accept slightly thicker layers.

A 23 cm (9 inch) round and a 20 cm (8 inch) square have nearly the same area and swap directly
Two 9 inch rounds hold slightly more than a 9 x 13; the 9 x 13 will be a little thicker
When eggs come out to a fraction, beat them and weigh; one large egg is about 50 g without the shell

Batter depth and pan volume

Area matching assumes pans of similar depth. Standard cake pans are 5 cm (2 inches) deep, and filling them one-half to two-thirds full leaves space to rise. A deeper 7.5 cm (3 inch) pan holds more batter, but a cake that thick takes longer and risks a dry edge.

For tube, Bundt or unusual pans, measure capacity instead: fill the pan with water using a measuring cup and note the volume. Fill a Bundt pan about two-thirds full and bake any extra batter as cupcakes.

Adjusting temperature and time

Thin batter in a large pan bakes faster, often 5 to 10 minutes sooner than the recipe states. Start checking early. Thick batter in a small or deep pan takes longer, and the outside may overbake before the center sets.

For batter deeper than about 5 cm, lower the oven by about 15°C (25°F) and expect a longer bake. A heating core or an upturned metal flower nail pressed into the center of pans 25 cm (10 inches) and larger helps conduct heat to the middle. Cupcakes bake at the original temperature in about 18 to 22 minutes.

Cupcakes and sheet cakes

A recipe for two 8 or 9 inch layers usually makes about 24 standard cupcakes, filled two-thirds full. A half sheet pan, 33 x 46 cm (13 x 18 inches), is about 234 sq in, or roughly twice a 9 x 13 pan, but it is shallower, so sheet cakes made in one often use about 1.5 times a 9 x 13 recipe for thin layers.

Dense batters such as cheesecake, brownies and pound cake are especially sensitive to depth. Scale them by area and adjust time carefully.

Checking doneness

Whatever the pan, a cake is done when the top springs back when pressed lightly, the edges begin to pull from the sides and a toothpick inserted in the center comes out clean or with a few moist crumbs. An instant-read thermometer in the center of most butter cakes reads about 93 to 99°C (200 to 210°F).

Common questions

Can I bake a layer cake recipe in a 9 x 13 pan without changing it?: Usually yes. Most two-layer 9 inch recipes fill a 9 x 13 pan nicely. The cake will be thicker, so bake at the same temperature for longer, often 30 to 40 minutes, and test it early.
What happens if I use a smaller pan without scaling?: The batter will be deeper and may overflow. If it fits, the edges overbake and the center can sink or stay underdone. Scale the recipe down or bake extra batter separately.
Does pan material affect conversions?: It affects time and browning. Dark metal and glass pans bake faster at the edges. With glass, many bakers lower the oven by about 15°C (25°F).

About this page

Written and reviewed by the BakedAI editorial team. Last reviewed 2026-10-14. This is general educational guidance, not professional or medical advice.