Baking Pan Size Converter
Find out whether you can swap one baking pan for another. The amount of batter a pan holds depends on its area, so two pans of the same area are roughly interchangeable even if their shapes differ — a 9-inch round pan, for example, holds almost exactly the same as an 8-inch square. Enter the pan a recipe calls for and the pan you actually own, and the converter compares their areas so you can decide whether the substitution works.
Calculate
Default result: 0.994
Baking Pan Size Converter · Result
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Substitution factor
round × 9 × 13 × square × 8 × 11
- Original pan area (in²)
- 63.6
- Target pan area (in²)
- 64.0
Reviewed by the calculators.dev team · Last updated 2026-06-24
Formula reviewed against Geometry of pan area (πr² / length × width); King Arthur Baking pan-substitution guidance
How to calculate
Choose the shape and size of the original pan and the pan you want to use instead. The converter works out each pan's area and divides the original by the target to give a substitution factor. A factor near 1 means the pans are interchangeable; below 1 the target is larger, so the batter spreads thinner and bakes faster; above 1 the target is smaller and may overflow. For round pans the size is the diameter; for square, the side; for rectangular, length × width.
Round pan area = π × (diameter ÷ 2)². Square or rectangular area = length × width. Substitution factor = original pan area ÷ target pan area. A 9-inch round (π × 4.5² ≈ 63.6 in²) into an 8-inch square (64 in²) gives 63.6 ÷ 64 ≈ 0.994.
Example calculation
A 9-inch round pan and an 8-inch square pan hold almost the same amount of batter. The round pan's area is π × 4.5² ≈ 63.6 in² and the square is 8 × 8 = 64 in², giving a substitution factor of about 0.994 — close enough to 1 that the two are effectively interchangeable.
- substitutionFactor
- 0.994
- originalArea
- 63.6
- targetArea
- 64
Assumptions
- This compares pan area, which governs how much batter fits, not pan depth — a shallower or deeper pan changes the bake even when the area matches, so this is an approximation, not a guaranteed result.
- A different pan area usually changes the baking time: a larger pan spreads the batter thinner and bakes faster, a smaller one slower. Check for doneness rather than relying on the original time.
- Pan dimensions are the nominal measurements; real pans vary slightly and have sloped sides, so treat the factor as a close guide.
Common mistakes
- Substituting only by shape, ignoring area — a 9×13 pan holds far more than two 8-inch rounds, so the swap is not one-for-one.
- Keeping the original bake time after switching pans. A thinner or thicker layer of batter bakes at a different rate.
- Overfilling a smaller pan, which causes the batter to spill or dome — leave room and bake any excess separately.
Frequently asked questions
Can I use an 8-inch square pan instead of a 9-inch round?
Yes. Their areas are almost identical (about 64 in² versus 63.6 in²), so the substitution factor is close to 1 and the two are effectively interchangeable.
How do I know if a pan substitution will work?
Compare the two pans' areas. If the substitution factor is close to 1, the swap works with little change; if it is well above or below 1, the batter depth and bake time will differ noticeably.
Does the pan depth matter?
Yes. This converter compares area only. A pan with the same area but a different depth holds the batter at a different thickness, which changes the baking time and texture.
Will the baking time change with a different pan?
Usually. A larger pan spreads the batter thinner and bakes faster; a smaller pan bakes slower. Start checking earlier or later than the original recipe and judge by doneness.