Baking Pan Size Converter – Round to Square & Volume

To convert a round pan to a square pan, you need to match the surface area. For a round pan with diameter d, the equivalent square side length is d × √π / 2 ≈ d × 0.886. For example, a 9-inch round pan has an area of about 63.6 sq in, which is nearly identical to an 8-inch square pan (64 sq in). This means an 8-inch square pan is the perfect substitute for a 9-inch round pan in most recipes.

A 9-inch round pan (area ≈ 63.6 sq in) is best matched by an 8-inch square pan (area = 64 sq in). The difference is less than 1%, making them virtually interchangeable. You can use the same batter amount, baking temperature, and roughly the same baking time. This is one of the most common pan substitutions in baking.

Yes, depth significantly affects volume and thus the amount of batter needed. If two pans have the same surface area but different depths, the deeper pan will hold more batter. Our calculator factors in depth to give you accurate volume comparisons in both cubic units and cups. If the volume difference is less than 5%, no recipe adjustment is needed. For 5-15% differences, monitor baking time. Above 15%, you should scale your recipe accordingly.

Baking time is primarily affected by batter depth (how thick the batter is in the pan). If your substitute pan has a larger surface area, the batter will be shallower and bake faster. Conversely, a smaller area means thicker batter and longer baking time. As a general rule: if the area increases by 10-15%, reduce baking time by 5-10 minutes and check for doneness early. Always rely on the toothpick test rather than exact timing when substituting pans.

Absolutely! Simply calculate the area of the rectangular pan (length × width) and find the round pan with the closest area. For example, a 9×13 inch rectangular pan has an area of 117 sq in, which is closest to a 12-inch round pan (113 sq in) or a 12.2-inch round for an exact match. Use our "Rect → Round" mode for this calculation. Note that rectangular pans often have shallower sides, so check the depth as well.

The most common round cake pans are 6", 8", 9", and 10" in diameter, typically 2" deep. Square pans commonly come in 8" and 9" sizes, also about 2" deep. Rectangular pans (like the classic 9×13") are usually 1.5-2" deep. Springform pans (used for cheesecakes) are often 9" or 10" round and 2.5-3" deep. Knowing these standards helps you choose the right substitute when a recipe calls for a specific pan.

Cake sinking often happens when the batter is too shallow in the pan (too large a pan for the amount of batter) or when the baking time isn't adjusted. A shallow batter bakes faster on the outside while the center may still be undercooked, causing collapse. Always aim for the batter to fill the pan 1/2 to 2/3 full. If substituting a significantly larger pan, consider increasing the recipe by the volume ratio shown in our calculator.

For round pans, measure the inside diameter from one inner edge to the opposite inner edge (not the outer rim). For square and rectangular pans, measure the inside length and width. For depth, measure the inside height from the bottom to the top rim. Most pans have the size stamped on the bottom, but older pans may have worn markings, so it's always good to measure manually. Use a ruler or measuring tape for accuracy.

Most baking pans worldwide are manufactured in inch-based sizes (6", 8", 9", 10", 12"), even in countries that primarily use metric. However, some European pans use centimeter measurements. For reference: 20 cm ≈ 7.9", 23 cm ≈ 9.1", 26 cm ≈ 10.2". Our calculator supports both inches and centimeters—simply toggle the unit switch. When in doubt, use inches as that's the baking industry standard.