Guides /Pan Sizes
Round to square
pan conversion.
The shape doesn't matter — only the base area does. Here's how to find the scale factor for any round-to-square or square-to-round swap.
The formula
Scale factor = Target pan area ÷ Original pan area
- —Round pan area = π × r² (r = half the diameter). An 8-inch round: π × 4² = 50.3 sq in.
- —Square/rectangle area = length × width. An 8×8: 64 sq in.
Common round-to-square conversions
| Original pan | Target pan | Scale factor |
|---|---|---|
| 8-inch round (50 sq in) | 8×8 square (64 sq in) | 1.28× |
| 9-inch round (64 sq in) | 8×8 square (64 sq in) | 1.0× |
| 9-inch round (64 sq in) | 9×9 square (81 sq in) | 1.27× |
| 10-inch round (79 sq in) | 9×9 square (81 sq in) | 1.03× |
| 8×8 square (64 sq in) | 9-inch round (64 sq in) | 1.0× |
| 9×13 rectangle (117 sq in) | 10-inch round (79 sq in) | 0.68× |
9-inch round = 8×8 square — a useful equivalence
The most useful pan equivalence in home baking: a 9-inch round pan (≈ 64 sq in) and an 8×8 square pan (64 sq in) have virtually the same base area. You can substitute one for the other with no change to ingredients or bake time. This is why many brownie and bar recipes that list "an 8×8 or 9-inch round" are genuinely interchangeable.
Bake time and depth
Scale factors close to 1.0 require no bake time adjustment. Larger differences in area mean the batter will be deeper or shallower in the target pan. If the scale factor is above 1.2 (target pan is bigger, batter is shallower), reduce bake time by 5–10 minutes and check early. If below 0.8 (target pan is smaller, batter is deeper), add 10–15 minutes and reduce temperature by 15–25°F / 10°C to prevent over-browning.
Pan material and heat conduction
The shape swap also changes the material if you're moving from a glass or ceramic round dish to a metal square pan. Metal pans conduct heat faster, so the edges of a cake or brownie set more quickly. Dark metal pans absorb more heat than shiny aluminium and can over-brown the bottom. If you're swapping from a light-coloured round pan to a dark square pan of the same area, reduce temperature by 25°F / 15°C to compensate. Glass and ceramic bakeware runs cooler and slower than metal — give it an extra 10–15 minutes and check the centre with a probe thermometer.
Lining and releasing baked goods from different shapes
Round pans release cleanly with a parchment circle cut to fit the base. Square pans are best lined with a parchment sling — cut two strips slightly wider than the pan, lay them perpendicular so they cross-hatch the base and overhang all four sides, then clip the corners. This gives you handles to lift the whole bake out cleanly, which is especially useful for brownies and bar cookies where you want to cut them outside the pan. If you're converting a recipe that normally uses a springform, remember the sides release mechanically — line the base and sides or use a non-stick spray if moving to a standard square pan.
Frequently asked questions
- Can I substitute a 9-inch round pan for an 8×8 square pan?
- Yes — a 9-inch round pan (≈ 64 sq in) and an 8×8 square pan (64 sq in) have virtually the same base area. Use the same ingredient quantities and bake time.
- How do I calculate the scale factor when swapping round and square pans?
- Scale factor = target pan area ÷ original pan area. Round pan area = π × r² (e.g. 8-inch round: π × 4² = 50.3 sq in). Square/rectangle area = length × width. Divide and multiply every ingredient by the result.
- Does bake time change when switching from a round to a square pan?
- Scale factors close to 1.0 need no bake time adjustment. If the target pan is more than 20% larger (batter shallower), reduce bake time by 5–10 minutes. If more than 20% smaller (batter deeper), add 10–15 minutes and reduce temperature by 15–25°F / 10°C.
- Does the pan material matter when swapping round and square pans?
- Yes. Metal pans conduct heat faster than glass or ceramic. Dark metal pans absorb more heat than shiny aluminium. Moving from a light round pan to a dark square pan of the same area: reduce temperature by 25°F / 15°C to prevent over-browning.
- What is the scale factor from a 9×13 pan to a 10-inch round pan?
- A 9×13 pan is 117 sq in; a 10-inch round is approximately 79 sq in. Scale factor = 79 ÷ 117 = 0.68×. You would use 68% of the recipe quantities to fill a 10-inch round from a 9×13 recipe.
Apply the scale factor to your recipe
Calculate your pan-area ratio, enter it as the scale factor, paste your ingredients — every quantity updates instantly.