How to use the baking pan size converter
- Choose the units, inches or centimeters. Both pans use the same unit, and nothing is converted behind your back.
- Pick the shape of the pan in the recipe and enter its diameter, side or length and width. Do the same for the pan you plan to use.
- Leave the scaling on pan area for pans of similar depth. If you know the inside depth of both pans, you can scale by volume instead.
- Multiply every ingredient by the multiplier. Read the note about checking for doneness, and compare the common pans in the table.
Formula
Round area = pi x diameter x diameter / 4
Square area = side x side
Rectangle area = length x width
Volume = area x depth
Multiplier = new pan area (or volume) / original pan area (or volume)
Dimensions are measured on the inside of the pan, at the top. One square inch is 6.4516 square centimeters, and a US cup is 14.4375 cubic inches.
Worked example
A recipe is written for a 9 inch round pan, whose area is pi x 9 x 9 / 4 = 63.62 square inches. You want to bake it in an 11 x 7 inch pan, which has an area of 77 square inches. The multiplier is 77 / 63.62 = 1.21, so multiply every ingredient by about 1.21.
If the 9 inch pan is 2 inches deep and the 11 x 7 pan is 1.5 inches deep, the volumes are 8.81 cups and 8.00 cups. By volume the multiplier is 0.908, so scaling by area would make a batter about 21 percent bigger than the deeper pan holds. Which number to trust depends on how full you want the pan.
Why area is the default
A cake or a pan of brownies is a layer of batter, and the thickness of that layer decides how it bakes. If the new pan has more surface, the same batter spreads thinner. Scaling the recipe by the ratio of areas keeps the layer about as thick as the original. This works well when the two pans are about the same depth, which is true of many everyday pans.
When to scale by volume
Loaf pans, springform pans and deep cake pans differ a lot in depth, so area alone can mislead. If you know both depths, the volume multiplier compares how much each pan can hold. Remember that batter rises, so pans are rarely filled to the brim. Use the volume figure as a ceiling check and your recipe for the fill level.
Baking time
The calculator does not give an exact new baking time, because time depends on the recipe, the oven, the pan material and the depth of batter. As a general guide, a thinner layer in a larger pan tends to set sooner, and a deeper layer in a smaller pan can take longer. Start checking early and use the doneness signs in your recipe, such as a clean toothpick or a set center. The line on the result called batter depth shows how deep the batter would be if you did not scale the recipe, as a share of the original depth.
Scaling the ingredients
Eggs do not divide neatly. For a multiplier like 1.21, round to the nearest whole egg or whisk one egg and measure part of it. Turn cups into grams with the ingredient grams to cups converter and check unit changes in the cooking measurement converter. The table in the result lists a few common pans, computed from the same formulas, as multiples of the pan in your recipe. They are not a claim about standard pan sizes.
Assumptions and limits
- Dimensions are inside measurements at the top of the pan. Sloped sides, fluted or novelty pans and tube pans are not modeled.
- Scaling by area assumes both pans have about the same depth and that you want a similar batter thickness.
- Volume uses the full pan depth. It is a comparison of capacity, not a fill level, and batter that rises needs room.
- Baking time is only a general note, never a computed time. Leavening, pan material, color and your oven all change it.
Frequently asked questions
How do I convert a 9 inch round pan to a 9 x 13 inch pan?
A 9 inch round has about 63.62 square inches and a 9 x 13 pan has 117, so the multiplier is about 1.84. Multiply each ingredient by that number, then check for doneness early because the batter will be thinner.
Is a 9 inch round the same as an 8 inch square?
Nearly. An 8 inch square has 64 square inches and a 9 inch round has 63.62, a ratio of 1.006. For most recipes you can swap them with no change in quantities.
Should I scale by area or volume?
Use area when the pans are about equally deep and the recipe makes a layer of batter. Use volume when depths differ a lot, such as swapping a loaf pan for a shallow sheet pan.
Does the bake time change when the pan changes?
Often, yes. A thinner layer usually sets sooner and a deeper layer later, but no formula gives the exact change. Use your recipe's doneness signs and start checking early.