Baking Pan Size Converter
Find the equivalent square or rectangular pan for a round pan, or compare pan areas to adjust baking times.
How to use this tool
- Enter pan shape, diameter / side / width and length (rectangular only) in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your pan area and the full breakdown beneath it.
Formula
Round pan area: A = π × (diameter ÷ 2)2
Square pan area: A = side2
Rectangular pan area: A = width × length
Area in cm²: Acm = Ain × 6.4516
Equivalent round diameter: d = 2 × √(A ÷ π)
Equivalent square side: s = √A
How it works
All pan shapes are compared by their base area in square inches. A round pan's area uses the circle formula (π r²), while square and rectangular pans use simple multiplication. Converting to square centimetres uses the factor 6.4516 (since 1 in² = 6.4516 cm²). The equivalent round and square pan dimensions are back-calculated from the area so bakers can substitute one pan shape for another with similar batter volume and baking behaviour.
A common mistake is substituting pans based only on stated size (e.g., swapping a 9-inch round for a 9-inch square) without checking the area difference — a 9-inch square pan (81 in²) holds about 27% more batter than a 9-inch round pan (≈ 63.6 in²), which will substantially change baking time and rise.
Worked example
Find the area and equivalent pans for a 9-inch round pan
- Shape: round. Diameter = 9 inches, so radius = 4.5 inches.
- Area: π × 4.5² = π × 20.25 ≈ 63.617 in².
- Area in cm²: 63.617 × 6.4516 ≈ 410.3 cm².
- Equivalent square side: √63.617 ≈ 7.98 inches.
A 9-inch round pan has an area of 63.617 in², equivalent to a square pan with approximately 7.98-inch sides.
Common mistakes to avoid
- Swapping a 9-inch round for a 9-inch square -- the square holds about 27% more batter (81 sq in vs 63.6 sq in for the round), which means the layer is thinner and bakes faster.
- Ignoring pan depth when substituting -- a 2-inch deep pan holds far less than a 3-inch deep pan of the same footprint; overfilling causes overflow and underbaking at the center.
- Adjusting only quantity and not baking time -- a shallower layer from a larger pan bakes 15-25% faster; not reducing time causes a dry, over-baked result.
Key terms
- Pan area (in²)
- The base surface area of a baking pan in square inches, used to compare capacity across different shapes and sizes.
- Equivalent pan
- A pan of a different shape whose base area matches the original pan's area closely enough to substitute in a recipe with minimal baking time adjustment.
- Square inch (in²)
- A unit of area equal to a square with 1-inch sides. One square inch equals 6.4516 cm².
- Batter depth
- The height to which batter fills a pan; pan area determines batter depth for a given recipe volume, which in turn affects baking time and rise.
Frequently asked questions
- Can I substitute a round pan for a square pan?
- Compare the pan areas. A 9" round pan (≈64 in²) is smaller than a 9" square (81 in²); use an 8" square instead. Adjust baking time for shallower batter.
- How does pan size affect baking time?
- A larger pan spreads batter thinner and bakes faster. A smaller pan has deeper batter and takes longer. Check for doneness 5–10 minutes earlier or later.