Cake pan size conversion chart
An 8 in round tin is not the same as an 8 in square.
Tins are compared by area, not by side or diameter. An 8 in round (50.3 sq in) matches a 7 in square, not an 8 in one, which has 27 % more area.
Area of the most common tins
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| Tin | Area | Roughly equivalent to |
|---|---|---|
| 6 in round | 28.3 sq in | 5 in square |
| 7 in round | 38.5 sq in | 6 in square |
| 8 in round | 50.3 sq in | 7 in square |
| 9 in round | 63.6 sq in | 8 in square |
| 10 in round | 78.5 sq in | 9 in square |
| 8 in square | 64 sq in | 9 in round |
| 9 in square | 81 sq in | 10 in round |
| 9 x 13 in rectangular | 117 sq in | 12 in round |
| 8 x 12 in rectangular | 96 sq in | 11 in round |
| 9 x 5 in loaf | 45 sq in | 7.5 in round |
Quick factors between round tins
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| From | To | Multiply the recipe by |
|---|---|---|
| 7 in | 8 in | 1.31 |
| 8 in | 9 in | 1.27 |
| 8 in | 10 in | 1.56 |
| 9 in | 10 in | 1.23 |
| 9 in | 8 in | 0.79 |
| 10 in | 9 in | 0.81 |
The square rule
The area of a circle is πr², so it grows with the square of the radius. Doubling the diameter multiplies the area by four, not two. That is the source of nearly every mistake when swapping tins.
To go from a round tin to a square of the same capacity, multiply the diameter by 0.886. The other way, divide by 0.886 (or multiply by 1.13).
Area or volume
Comparing by area assumes the batter will sit at a similar depth in both tins, which is usually the case. If one tin is noticeably deeper (a tall cake tin against a sheet pan), compare by volume: area times height.
Baking time changes
A wider tin spreads the batter thinner and bakes sooner; a narrower, deeper one takes longer and sometimes needs 25 °F less so the outside does not burn before the middle sets. Start checking 10 minutes before the stated time.
Sources and methodology
All the figures are geometry: the area of a circle, a square and a rectangle. Conversion factors are the ratio of those areas.
Frequently asked questions
Is an 8 inch round tin the same as an 8 inch square?
No. The square has 64 sq in and the round 50.3: 27 % more. The equivalent square would be 7 inches.
How do I convert a round tin to a square one?
Multiply the round tin's diameter by 0.886 to get the equivalent square side. A 9 in round matches an 8 in square.
How much batter do I need going from 8 to 10 inches?
56 % more. The area goes from 50.3 to 78.5 sq in, so multiply every ingredient by 1.56.
Should I compare by area or volume?
By area if the batter depth will be similar. By volume if the tins have very different depths.
How full should I fill the tin?
About two thirds of its height for chemically leavened batters. Beyond that it can overflow as it rises.