BAKING NOTE
Round to square cake pan conversion
An 8-inch round pan and an 8-inch square pan do not hold the same batter at the same depth. The square has more base area: multiply the round-pan recipe by 1.273240… to keep the batter depth unchanged.
1.27324×
Square area ÷ round area = 64 ÷ (16π)
Set up the round-to-square recipe calculator →Square pans use the Rectangle option with equal width and length. Apply settings before changing your ingredients.
TRY YOUR OWN NUMBERS
Calculate right here
Enter your measurements and ingredient weights. This example illustrates the math; it is not a tested recipe.
Your scaled amounts
| Ingredient | Original | Scaled |
|---|
These inputs stay on this page and clear on reload. Your saved recipes and working draft are unchanged. Use the full calculator to save a recipe or download it.
Choose between matching a pan and scaling the recipe
If you want to use the original quantity of batter, choose a square pan with approximately the same base area. If you already own a different square pan, divide its area by the original round pan’s area and scale the ingredients. These are two different questions.
Round area = π × (diameter ÷ 2)². Square area = side². At equal depth, an equivalent square side is round diameter × √π ÷ 2, approximately 0.886227 times the diameter. Use one unit consistently.
| Round diameter | Equivalent square side |
|---|---|
| 6 in | 5.32 in |
| 7 in | 6.20 in |
| 8 in | 7.09 in |
| 9 in | 7.98 in |
| 10 in | 8.86 in |
| 12 in | 10.63 in |
Equivalent sides are rounded to 0.01 inch and are mathematical targets, not promises that such pans are commercially available. A 9-inch round is close to an 8-inch square: their areas are about 63.62 and 64 square inches. An 8-inch round is close to a 7.09-inch square, not an 8-inch square.
Ratios for common swaps
| Original → new | Multiplier | Batter change |
|---|---|---|
| 8-inch round → 8-inch square | 1.273240 | +27.3% |
| 9-inch round → 8-inch square | 1.006016 | +0.6% |
| 8-inch round → 9-inch square | 1.611444 | +61.1% |
| 10-inch round → 9-inch square | 1.031324 | +3.1% |
For multiple pans, multiply each area by its pan count before dividing. For rectangular pans that are not square, use width × length. Measure inside the base of the pan, especially when the rim is wider than the bottom.
Worked ingredient example
Suppose your trusted 8-inch round recipe uses 200 g flour. In an 8-inch square at the same batter depth, the new amount is 200 × 64 ÷ (16π) = 254.6 g, rounded to 0.1 g. For 120 g sugar, the result is 152.8 g. Apply the ratio to each weighed ingredient in the full recipe. These weights illustrate the calculation; they are not a complete or tested recipe.
Going from square to round
Reverse the area ratio. An 8-inch square to an 8-inch round usesπ ÷ 4 = 0.785398…. The equal-area round diameter for a square of side s is 2s ÷ √π. An 8-inch square therefore matches approximately a 9.03-inch round.
Set up the square-to-round recipe calculator →
What the area calculation cannot tell you
Equal base area is useful only when the intended batter depth is also equal. Corners, pan material and oven behavior can still change how a cake bakes. Check doneness using the original recipe’s guidance rather than multiplying baking time by the ingredient ratio.
Do not use these tables as capacity estimates for tapered loaf tins, Bundt pans, pans with a center tube or irregular molds. Keep space for rising batter. If you intentionally change batter depth, the full calculator can include that ratio, but it does not predict finished texture or height.
Method and related guides
These independently calculated tables use base areas and assume straight sides. For practical pan substitutions, see King Arthur Baking’s alternative baking pan sizes. For two round pans, see 8-to-9-inch conversion; for a limited stock of butter or flour, see scaling by available ingredient weight.