How pan conversion works
What matters when you switch pans is the floor area. If the new pan has more area, the same batter spreads thinner and bakes faster; if it has less, the batter sits deeper and takes longer, or overflows. Multiplying the recipe by the ratio of the two areas keeps the batter at its original depth, so it bakes in roughly the original time.
The formula
square or rectangular area = length × width
scale factor = new pan area ÷ recipe's pan area
unscaled depth = recipe's pan area ÷ new pan area
Example: 8x8 recipe in a 9x13 pan
| Step | Result |
|---|---|
| 8x8 area: 8 × 8 | 64 sq in (413 cm²) |
| 9x13 area: 9 × 13 | 117 sq in (755 cm²) |
| Scale factor: 117 ÷ 64 | × 1.83 |
| Easy multiplier | about 1 3/4× |
| Batter needed | 83% more |
| Without scaling: 64 ÷ 117 | 55% of the original depth |
Common pan areas
| Pan | Area (sq in) | Typical depth |
|---|---|---|
| 9x5" loaf | 45 | 2 1/2–3" |
| 8" round | 50 | 2" |
| 9" round | 64 | 2" |
| 8x8" square | 64 | 2" |
| 11x7" baking dish | 77 | 1 1/2–2" |
| 10" round | 79 | 2" |
| 9x9" square | 81 | 2" |
| 9x13" pan | 117 | 2" |
| Half sheet, 18x13" | 234 | 1" |
Measure across the top inside edges if you're unsure of a pan's size. Sloped sides make the bottom a little smaller, which this simple area math ignores.
Pan swapping tips
- Equal-area swaps are free. A 9" round and an 8x8 square hold the same, as do a 10" round, an 11x7 and a 9x9 within a few percent.
- Deeper means slower. Batter that ends up deeper needs more time and sometimes 25 °F less heat.
- Glass and dark pans run hot. Many bakers lower the oven 25 °F for glass or dark metal.
- Use the recipe scaler. Plug the factor into our recipe scaler to rewrite every ingredient.
Frequently asked questions
How do I convert an 8x8 recipe to a 9x13 pan?
A 9x13 pan has 117 square inches against 64 for an 8x8, so multiply the recipe by about 1.83. In practice, 1 3/4 times the recipe works well, or simply double it and accept slightly thicker brownies or bars, adding a few minutes of baking time.
Can I use a 9-inch round pan instead of an 8-inch square?
Yes. A 9-inch round is about 64 square inches, almost exactly the same as an 8-inch square, so you can swap them without changing the recipe or baking time much.
How many 9-inch rounds equal a 9x13 pan?
Two 9-inch rounds total about 127 square inches, a little more than a 9x13's 117. Batter for a two-layer 9-inch cake will fill a 9x13 slightly deeper than the rounds; bake it a bit longer and test with a toothpick.
Do I need to change the baking time for a different pan?
If you scale the batter so it's the same depth, the time stays close to the original. If the batter ends up deeper, bake longer, sometimes at 25 °F lower so the edges don't overbake; if it's shallower, start checking early. Always test for doneness rather than trusting the clock.
How full should I fill a cake pan?
About half to two-thirds full for most cake batters, leaving room to rise. Overfilled pans can overflow or sink in the middle.
Rates and figures last checked October 2026.
This calculator gives estimates for planning. Check current rates and product labels before you buy, list or file.