Round pans and square pans of the same inch measurement are not the same size. A 9-inch round pan holds about 63.6 square inches of area; a 9x9 square pan holds 81 square inches. The square is 27% larger.
Area formula for a round pan: pi × radius squared = 3.14159 × (diameter ÷ 2)²
Use this to compare any round and square pan pair.
Pan Area Reference Table
| Pan | Area (sq in) | Notes |
|---|---|---|
| 6-inch round | 28.3 | Small cake layer |
| 8-inch round | 50.3 | Standard two-layer cake |
| 9-inch round | 63.6 | Most common cake size |
| 10-inch round | 78.5 | Larger celebration cake |
| 8x8 square | 64 | Brownies, bar cookies |
| 9x9 square | 81 | Snack cakes, cornbread |
| 9x13 rectangle | 117 | Sheet cake, casseroles |
| 8x4 loaf | 32 | Banana bread, pound cake |
| 9x5 loaf | 45 | Standard sandwich loaf |
Conversion Multipliers: Round to Square
| Round pan → Square pan | Multiplier | Notes |
|---|---|---|
| 9-inch round → 8x8 square | 64 ÷ 63.6 = 1.01 | Nearly identical — no adjustment needed |
| 9-inch round → 9x9 square | 81 ÷ 63.6 = 1.27 | Add 27% to every ingredient |
| 8-inch round → 8x8 square | 64 ÷ 50.3 = 1.27 | Add 27% to every ingredient |
| 8-inch round → 9x9 square | 81 ÷ 50.3 = 1.61 | Add 61% — or use 1.5x recipe |
Conversion Multipliers: Square to Round
| Square pan → Round pan | Multiplier | Notes |
|---|---|---|
| 9x9 square → 9-inch round | 63.6 ÷ 81 = 0.79 | Use 80% of the recipe |
| 8x8 square → 8-inch round | 50.3 ÷ 64 = 0.79 | Use 80% of the recipe |
| 8x8 square → 9-inch round | 63.6 ÷ 64 = 0.99 | Same recipe, nearly identical |
Worked Example: Birthday Cake From Square to Round
Your recipe is written for a 9x9 square pan. You want to bake it in a 9-inch round cake pan.
Multiplier = 63.6 ÷ 81 = 0.79
Original recipe:
| Ingredient | 9x9 amount | × 0.79 | 9-inch round amount |
|---|---|---|---|
| Flour | 250 g | × 0.79 | 197 g |
| Sugar | 200 g | × 0.79 | 158 g |
| Butter | 115 g | × 0.79 | 91 g |
| Eggs | 2 | × 0.79 | 1.6 (use 2; minor difference) |
| Buttermilk | 120 ml | × 0.79 | 95 ml |
| Baking powder | 1.5 tsp | × 0.79 | 1.2 tsp |
The round pan will have almost exactly the same batter depth as the square, so baking time and temperature stay the same.
Worked Example: Brownie Recipe From Round to Square
You have an 8-inch round brownie recipe and want to fill a 9x9 square pan.
Multiplier = 81 ÷ 50.3 = 1.61
| Ingredient | 8-inch round amount | × 1.61 | 9x9 square amount |
|---|---|---|---|
| Butter | 115 g | × 1.61 | 185 g |
| Sugar | 200 g | × 1.61 | 322 g (use 320 g) |
| Eggs | 2 | × 1.61 | 3.2 (use 3) |
| Flour | 65 g | × 1.61 | 105 g |
| Cocoa | 50 g | × 1.61 | 80 g |
With 3 eggs instead of 3.2, the batter will be very slightly stiffer — the difference in a dense brownie is negligible. Use the full recipe and add any leftover batter to a ramekin.
Batter Depth and When It Changes
All the multipliers above assume you keep batter depth constant — the same height of batter in the new pan as in the original. If batter depth changes significantly, baking time must change too:
- Thinner batter (smaller multiplier, larger pan): bakes faster. Reduce time 5–10 minutes and check early.
- Thicker batter (larger multiplier, smaller pan): bakes slower. Reduce oven temperature 25°F and extend time by 5–15 minutes. Check with a probe thermometer: 200°F for cakes, 205°F for dense quick breads.
If you switch shapes (say, a round layer cake to a 9x9 square) without scaling the recipe, your batter will be shallower in the larger pan. The result bakes faster and has a slightly different texture — denser and more like a bar than a tall round cake.
Springform and Cake Ring Conversions
A 9-inch springform pan has the same base area as a 9-inch round cake pan (63.6 sq in). You can substitute one for the other without changing the recipe, with these notes:
- Springform → round: Line the bottom of the regular round pan with parchment. The cake must cool completely before unmolding to avoid sticking.
- Round → springform: The springform sides may leak if the batter is very liquid. Wrap the outside of the base in aluminum foil before filling.
- 9-inch springform → 8x8 square: Areas are nearly identical (63.6 vs. 64 sq in). No recipe adjustment needed; check doneness a few minutes earlier since corners of square pans conduct extra heat.
When a Round Recipe Fits a 9-Inch Round Exactly
A standard two-layer round cake recipe built for two 9-inch pans (63.6 sq in each) can also bake in one 9-inch round for a taller, single-layer cake — or in a 9x9 square by using 1.27× the recipe. This is a common reason bakers switch between shapes without adjusting the recipe.
Use the pan size converter calculator to enter any two pan dimensions and get the multiplier automatically.
For how switching pans affects baking time, see adjust baking time for pan size.