Baking-pan area converter
Work out a rectangular baking pan's area, and the diameter of a round tin with the same baking area — useful for substituting one pan for another.
Result
Baking area
Equivalent round tin diameter
How to use this calculator
- Measure the pan's internal length and width.
- Read its baking area, and the equivalent round tin diameter with the same area.
Assumptions
- Matches baking area only, not depth — use a pan of similar depth too, or adjust baking time if the depths differ noticeably.
Technical details: what the fields mean
- Length
length - Internal length of the pan.
- Width
width - Internal width of the pan.
Methodology
Area = length × width. Equivalent round diameter = 2 × √(area ÷ π) — the diameter of a circle with the same area.
Worked example
20cm × 20cm pan
Inputs: length=20, width=20
Result: 400cm² area, equivalent to a 22.6cm round tin
Practical guidance
- When substituting a rectangular pan for a round one (or vice versa) with a similar area, check for doneness a few minutes early — corners and edges can cook slightly faster than curves.
Common mistakes
- Assuming two pans with similar-sounding dimensions (e.g. '20cm round' vs '20cm square') actually have the same baking area — they usually don't.
FAQs
What round tin is equivalent to a 20cm x 20cm square pan?
About a 22.6cm diameter round tin, matching the same 400cm² baking area.