Formula
A round pan uses the circle area. A rectangular or square pan uses length times width:
multiplier = new area / original area
For two round pans the pi terms cancel, so an 8-inch pan to a 9-inch pan is (4.5 / 4) squared. The multiplier is rounded to three decimal places. Baking time is not scaled.
Assumptions
- Both measurements use the unit you select.
- Width is ignored for a round pan. Diameter is the first measurement.
- The pans are filled to a similar depth. A much deeper pan is a different decision.
Worked example
A 9-inch round pan has 1.266 times the area of an 8-inch round pan.
Input definitions
- Diameter or length
- The diameter of a round pan, or the longer side of a rectangular pan.
- Width
- The second side. Enter it only for a rectangular or square pan.
Limitations
Area scales ingredients. It does not tell you whether the batter will overflow, or how long the new pan should bake.
Questions
How do I enter a square pan?
Choose rectangular or square and enter the same number for length and width.
Does a larger multiplier mean a longer bake?
Not by itself. A wider, shallower layer can finish sooner. Use the multiplier for ingredients only.