30 cm / 12 in round vs 20 × 30 cm traybake
| 30 cm / 12 in round | 20 × 30 cm traybake | |
|---|---|---|
| Size | 30 cm across | 20 × 30 cm |
| Base area | 706.9 cm² | 600 cm² |
| Usual depth | 5 cm | 5 cm |
| Holds | 3.53 L | 2.7 L |
Can you swap them?
Swap without changing the recipe, but watch the oven. 30 cm / 12 in round has 17.8% more area, so a mixture written for 20 × 30 cm traybake sits about 85% as deep in it and browns sooner.
Nothing standard sits between these two, so this is the smallest change available in this shape.
Scaling the recipe
| Recipe written for | Baked in | Multiply by | Or leave it and get |
|---|---|---|---|
| 30 cm / 12 in round | 20 × 30 cm traybake | 0.85 | 118% of the depth |
| 20 × 30 cm traybake | 30 cm / 12 in round | 1.18 | 85% of the depth |
Multiply every ingredient, including the eggs — round to the nearest half egg and adjust the liquid rather than rounding a whole one up.
Baking time
A mixture 85% as deep is done earlier, not cooler. Leave the temperature alone, start testing at about 85% of the stated time, and let the skewer decide. Why depth sets the time and diameter barely does →
Frequently asked questions
Can I use a 20 × 30 cm traybake instead of a 30 cm / 12 in round?
Yes, with the mixture multiplied by 0.85. 20 × 30 cm traybake has 600 cm² of base against 706.9 cm², so an unscaled 30 cm / 12 in round recipe sits 118% as deep and bakes faster.
What is the difference between a 30 cm / 12 in round and a 20 × 30 cm traybake?
30 cm / 12 in round has a base area of 706.9 cm² and 20 × 30 cm traybake has 600 cm² — 30 cm / 12 in round is 17.8% larger. At their usual depths they hold 3.53 L and 2.7 L.
Do I need to change the baking time between a 30 cm / 12 in round and a 20 × 30 cm traybake?
Yes. Moving a 20 × 30 cm traybake mixture into 30 cm / 12 in round makes it 85% as deep, so start checking at about 85% of the stated time. Depth drives baking time far more than tin diameter does.
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