Pan Size Converter
Calculate the scale factor when changing baking pan sizes.
Pick the original and new pan shapes and dimensions. Get the scale factor to multiply every ingredient by.
Original pan
New pan
Why pan size matters in baking
Baked goods rise and cook based on the surface area and depth of the batter. Switching pans without adjusting the recipe changes how the batter cooks: too-thick batter undercooks in the middle and overcooks on the edges; too-thin batter dries out. This calculator gives you the area-based scale factor so you can multiply (or divide) the entire recipe to fit a different pan.
How the scale factor works
Scale factor = new pan area divided by original pan area. If the new pan is 1.25x the area of the original, multiply every ingredient by 1.25. A 9-inch round (63.6 sq in) is about 80 percent of a 9-inch square (81 sq in), so you would multiply by 0.78 going from square to round.
Common pan equivalents
- 8-inch round (50 sq in) ~ 7-inch square (49 sq in)
- 9-inch round (64 sq in) ~ 8-inch square (64 sq in)
- 10-inch round (79 sq in) ~ 9-inch square (81 sq in)
- 9x13 rectangular (117 sq in) ~ two 9-inch rounds (127 sq in combined)
Cooking time adjustments
A larger pan means shallower batter, which usually means shorter cooking time. A smaller pan means deeper batter, longer time. Start checking doneness about 70 percent through the original time and adjust. Use a toothpick or thermometer to verify, not the clock.