Baking Pan Size Converter

How the conversion works

Batter spreads to fill the bottom of the pan, so what matters is the area of the base.

• Round pan: area = 3.1416 x radius x radius
• Square or rectangular pan: area = width x length

The calculator divides the area of the pan you have by the area of the pan the recipe uses.

scale factor = area of your pan / area of the recipe’s pan

Multiply every ingredient by that factor and the batter will sit at the same depth as in the original recipe. That is the important part, because depth is what sets the baking time.

Worked example

A brownie recipe is written for an 8 inch square pan. You want to make it in a 13 x 9 inch pan for a party.

1. 8 inch square: 8 x 8 = 64 square inches.
2. 13 x 9 inch pan: 13 x 9 = 117 square inches.
3. 117 / 64 = 1.83.

Multiply each ingredient by 1.83. In practice most bakers double the recipe, which makes the brownies about 10 percent deeper, and add a few minutes.

Pan areas at a glance

• 6 inch round: 28 square inches
• 8 inch round: 50 square inches
• 9 inch round: 64 square inches
• 10 inch round: 79 square inches
• 8 inch square: 64 square inches
• 9 inch square: 81 square inches
• 11 x 7 inch: 77 square inches
• 13 x 9 inch: 117 square inches
• 18 x 13 inch half sheet: 234 square inches
• 8 1/2 x 4 1/2 inch loaf: 38 square inches
• 9 x 5 inch loaf: 45 square inches

A few useful matches fall out of those numbers:

• A 9 inch round and an 8 inch square are the same size.
• A 10 inch round and an 11 x 7 inch pan are within 2 percent of each other.
• A half sheet is exactly two 13 x 9 inch pans.
• One inch of diameter matters more than it looks: a 9 inch round is 27 percent bigger than an 8 inch round, and a 6 inch round holds less than half of a 9 inch.

When you do not want to scale

Sometimes you want to bake the recipe as written in a different pan. That works when the factor is close to 1: anything between 0.9 and 1.1 needs no change.

Outside that range you have two choices:

• Bigger pan, same batter. The layer will be thinner. It bakes faster and can dry out, so start checking well before the original time.
• Smaller pan, same batter. The layer will be deeper. Do not fill any pan more than about two thirds full, or it may overflow. Bake the extra batter as cupcakes.

Depth and baking time

The calculator compares area only, which assumes the pans are about the same height. Most cake and brownie pans are around 2 inches deep, so this holds for the usual swaps.

If you keep the batter at the same depth, keep the oven temperature and the time roughly the same. If the batter ends up deeper, the center takes longer to set while the edges keep cooking. Lowering the oven by 25 °F and baking longer helps the middle catch up.

Tips and common mistakes

Measure your pan across the inside top edge. Pans are sold by nominal size, and some slope inward, so the base is smaller than the label suggests.

Eggs do not scale neatly. A factor of 1.27 on a 2 egg recipe gives 2.5 eggs. Beat an extra egg and add half, or use the Recipe Scaler to see every line of the recipe at the new size.

Loaf pans are deeper than cake pans. Comparing a loaf pan with a cake pan by area understates how much the loaf pan holds, so use the factor for loaf to loaf swaps only.

Springform and tart pans follow the same math as any round pan. Use the inside diameter.

Dark and glass pans bake hotter than shiny metal ones. If you move from a light metal pan to glass or a dark nonstick pan, check earlier.