Kitchen tools
Pan size converter
The recipe wants a 20 cm round and you have an 8 inch square. Pick both tins and this tells you how much to scale the recipe so it bakes the same.
Common tins compared
Against a 20 cm round sandwich tin, the tin most British cake recipes use. Multiply a 20 cm recipe by the figure to fill the other tin to the same depth.
| Tin | Base area | Scale |
|---|---|---|
| 15 cm round | 177 cm² · 27 in² | 0.56 |
| 18 cm round | 254 cm² · 39 in² | 0.81 |
| 20 cm round | 314 cm² · 49 in² | 1.00 |
| 23 cm round | 415 cm² · 64 in² | 1.32 |
| 25 cm round | 491 cm² · 76 in² | 1.56 |
| 6 inch round | 182 cm² · 28 in² | 0.58 |
| 8 inch round | 324 cm² · 50 in² | 1.03 |
| 9 inch round | 410 cm² · 64 in² | 1.31 |
| 10 inch round | 507 cm² · 79 in² | 1.61 |
| 18 cm square | 324 cm² · 50 in² | 1.03 |
| 20 cm square | 400 cm² · 62 in² | 1.27 |
| 23 cm square | 529 cm² · 82 in² | 1.68 |
| 8 inch square | 413 cm² · 64 in² | 1.31 |
| 9 inch square | 523 cm² · 81 in² | 1.66 |
| 30 × 20 cm traybake | 600 cm² · 93 in² | 1.91 |
| 33 × 23 cm traybake | 759 cm² · 118 in² | 2.42 |
| 13 × 9 inch pan | 755 cm² · 117 in² | 2.40 |
| 11 × 7 inch pan | 497 cm² · 77 in² | 1.58 |
Loaf, bundt and ring tins vary too much between makers for a chart. Measure yours, or fill both with water from a jug and compare. More shapes are on the way; see all tools.
Tin size questions
Can I bake an 8 inch recipe in a 9 inch round pan?
Yes. A 9 inch round has 27% more room than an 8 inch, so multiply the recipe by 1.27 (about 1¼ times) to keep the same depth and bake time. Unscaled, the cake comes out about 21% thinner and bakes faster.
What size square tin is the same as a 20 cm round?
An 18 cm square. A 20 cm round has the same area as a 17.7 cm square, so an 18 cm square is within 3%. A 20 cm square is 27% bigger.
How much bigger is a 9 × 13 inch pan than a 20 cm round?
A 9 × 13 inch pan holds 2.4 times a 20 cm round at the same depth, so a sponge recipe made for two 20 cm sandwich tins needs multiplying by 1.20 to fill it at the same depth.
Why does a slightly bigger tin need so much more batter?
Area grows with the square of the size. Going from 20 cm to 23 cm across is 15% wider but 32% more area, so it needs about 1⅓ times the batter.
Do I change the bake time?
If you scale the recipe so the batter is the same depth, the time stays close; start checking a few minutes early. If you do not scale it, a bigger tin gives a thinner cake that bakes faster, and a smaller one a deeper cake that takes longer and needs a tin deep enough to hold it.