Free Cake Pan Size Converter calculator
A cake pan size converter rescales a recipe between pan sizes by baking area, so it bakes to the same depth in the pan you own — updated live, as you type.
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Scaling is by baking area; batter depth and bake time still shift. How accurate is this?
Results are estimates. Consult a professional.
How the cake pan size converter works
Cake batter spreads across the bottom of the pan, so the amount a recipe needs scales with the pan's baking area — not its diameter, and not its volume. The converter finds the area of the pan your recipe was written for, finds the area of the pan you want to use, and divides the second by the first. That ratio is your scale factor. Multiply every ingredient by it and the batter rises to the same depth in the new pan.
Why area, not diameter
A 9-inch round pan sounds barely bigger than an 8-inch one. By area it holds more than a quarter more batter, because area grows with the square of the radius. Pour an 8-inch recipe into a 9-inch pan unchanged and the cake bakes thinner, drier and faster. The square in the formula is the whole reason a converter beats guessing by diameter.
A worked example: 8-inch round to 9-inch round
Maria's layer-cake recipe calls for an 8-inch round pan and 1½ cups of flour. She only owns a 9-inch round. She needs to know how much to scale every ingredient so the cake isn't thin and overbaked.
Step 1 — Area of the original pan
The 8-inch round has a 4-inch radius: π × 4² = 50.27 sq in.
Step 2 — Area of the new pan
The 9-inch round has a 4.5-inch radius: π × 4.5² = 63.62 sq in.
Step 3 — Divide to get the scale factor
63.62 ÷ 50.27 = 1.27 — the 9-inch pan holds about 27% more batter. So 1½ cups of flour becomes 1.5 × 1.27 = 1.90 cups, and every other ingredient scales the same way.
Common cake pan areas at a glance
If you just want to eyeball a swap before reaching for the calculator, this table lists the baking area of the pans most home recipes use. Pans with nearly equal areas are interchangeable with little or no scaling.
| Pan | Dimensions | Baking area (sq in) | Batter (cups) |
|---|---|---|---|
| 6" round | 6 × 2 in | 28.3 | 3–4 |
| 8" round | 8 × 2 in | 50.3 | 6 |
| 9" round | 9 × 2 in | 63.6 | 8 |
| 10" round | 10 × 2 in | 78.5 | 10–11 |
| 8" square | 8 × 8 in | 64.0 | 8 |
| 9" square | 9 × 9 in | 81.0 | 10 |
| 11 × 7" rect | 11 × 7 in | 77.0 | 10 |
| 9 × 13" rect | 13 × 9 in | 117.0 | 14 |
| 9 × 5" loaf | 9 × 5 in | 45.0 | 8 |
Areas are geometry; batter capacities follow Sally's Baking Addiction. An 8" square (64 sq in) and a 9" round (63.6 sq in) are the classic interchangeable pair.
Converting round to square (and back)
Round and square pans swap freely once you compare them by area. The shapes look different, but the batter only cares how much floor it has to cover. The classic example is the one King Arthur leads with.
An 8-inch square is 8 × 8 = 64 sq in. A 9-inch round is 4.5² × π = 63.6 sq in. Within a hair of each other, so a recipe written for one bakes in the other with no scaling at all. A square pan runs a touch larger than the round of the same number because its corners add area the circle doesn't have.
Scaling across multiple pans and layers
A layer cake or a doubled batch spreads batter across several pans, so add their areas together before you divide. The converter does this for you when you set the pan count, but the logic is worth seeing.
Say a sheet recipe fills one 9 × 13 pan (117 sq in) and you'd rather bake two 8-inch rounds. Two rounds total 2 × 50.3 = 100.5 sq in. Divide: 100.5 ÷ 117 = 0.86, so scale the recipe to about 86% — or accept slightly taller layers and bake it as-is.
The same addition works the other way. Three 6-inch rounds give a tall, dramatic tier; two 9-inch rounds give a wider, lower cake. Total the areas, divide by what your recipe was built for, and the scale factor tells you whether you're stretching the batter thin or piling it deep.
Adjusting bake time and temperature
Scaling the ingredients is only half the job. The new pan changes how deep the batter sits, and depth changes how the cake bakes. A wider, shallower pan bakes faster; a smaller, deeper pan bakes slower and risks a raw centre under a set top. Most pan-size charts stop at the scale factor and leave you to guess the rest.
Wider and shallower — bake hotter and shorter
Spreading the same batter over more area makes a thinner layer that sets quickly. Keep the recipe temperature or nudge it up about 25°F, and start checking for doneness several minutes before the original time. A thin cake left in too long dries out at the edges.
Smaller and deeper — bake cooler and longer
Pile the batter into a smaller, deeper pan and the centre takes longer to reach temperature. Lower the oven about 25°F so the outside doesn't overbake while the middle catches up, and add 10–25 minutes. Going from a 2-inch to a 3-inch pan is the common case where this matters most.
When to use a cake pan converter
Reach for it whenever the pan you own isn't the pan the recipe names — which is most of the time, because every recipe assumes one specific pan and no kitchen stocks them all.
- Wrong-size pan — your recipe calls for a 9-inch round and you only have an 8-inch, or vice versa.
- Round to square (or back) — turning a layer cake into a sheet cake, or a square recipe into rounds.
- Layer cakes — splitting one batter across two or three tiers of a given size.
- Scaling a recipe up or down — halving a sheet cake into a single round, or doubling a round into a 9 × 13.
- Bundt and tube pans — matching batter volume to a 10- or 12-cup mould.
For converting the ingredient units themselves — cups to grams, sticks of butter, tablespoons — pair this with the cooking converter.
Cake pan terms, defined
How accurate is this cake pan converter?
The area math is exact. π times radius squared, and length times width, are precise to the decimal, so the scale factor between any two pans is as accurate as your measurements. Measure across the top inside edge, since the outside dimension includes the pan walls.
What the converter can't predict is how your specific cake behaves at a new depth. Scaling the ingredients keeps the batter at the same depth when the fill level matches, but bake time, doming and edge texture still shift with the pan's shape and your oven. Treat the scale factor as exact, the bake time as a starting point, and test for doneness with a skewer rather than the clock. When in doubt, keep the new layer close to the depth the recipe was written for.
Frequently asked questions about the free Cake Pan Size Converter calculator
About this Cake Pan Size Converter calculator
This converter runs entirely in your browser — nothing is sent anywhere. Enter the pan your recipe was written for and the pan you want to use, and it works out the area of each, divides them for the scale factor, and rescales any ingredient amount you type, all live as you adjust the dimensions.
It's part of our cooking and baking calculators, alongside the full library of free calculators for everyday kitchen math.