KitchenCake tin size conversion
The recipe says "an 8 inch round tin" and the cupboard holds a 6 inch tin, a 9 inch tin and a square one. Batter does not care about the shape of the tin. It cares about the area of the base, because that decides how deep it sits. Match the area and the cake bakes as the recipe intended.
Round tins: area and the matching square
| Round tin | Base area | Matching square tin | Compared with 8 inch |
|---|---|---|---|
| 5 inch (13 cm) | 127 sq cm | 4.4 inch (11 cm) | 0.39 |
| 6 inch (15 cm) | 182 sq cm | 5.3 inch (14 cm) | 0.56 |
| 7 inch (18 cm) | 248 sq cm | 6.2 inch (16 cm) | 0.77 |
| 8 inch (20 cm) | 324 sq cm | 7.1 inch (18 cm) | 1.00 |
| 9 inch (23 cm) | 410 sq cm | 8.0 inch (20 cm) | 1.27 |
| 10 inch (25 cm) | 507 sq cm | 8.9 inch (23 cm) | 1.56 |
| 12 inch (30 cm) | 730 sq cm | 10.6 inch (27 cm) | 2.25 |
Area is worked out as π × radius × radius. "Matching square tin" is the side of a square with the same area. The last column compares each tin with an 8 inch round.
The simple rule for round and square
A square tin holds about the same as a round tin one inch wider. A 7 inch square is close to an 8 inch round, and an 8 inch square is close to a 9 inch round. Corners make the difference.
For a rectangular tin, multiply the length by the width to get the area and compare it with the table. A 9 × 5 inch loaf tin has a base of 45 square inches (290 sq cm), a little under an 8 inch round. Loaf tins are deeper, so the cake will be taller and take longer.
Changing the size of the recipe
To move a recipe from one round tin to another, multiply every ingredient by the factor where the row of the recipe's tin meets the column of your tin.
| From \ To | 6 in | 7 in | 8 in | 9 in | 10 in |
|---|---|---|---|---|---|
| 6 in | 1.00 | 1.36 | 1.78 | 2.25 | 2.78 |
| 7 in | 0.73 | 1.00 | 1.31 | 1.65 | 2.04 |
| 8 in | 0.56 | 0.77 | 1.00 | 1.27 | 1.56 |
| 9 in | 0.44 | 0.60 | 0.79 | 1.00 | 1.23 |
| 10 in | 0.36 | 0.49 | 0.64 | 0.81 | 1.00 |
Going from an 8 inch tin to a 6 inch tin, the factor is 0.56: a little over half the recipe. Going from 8 to 10, it is 1.56: one and a half times the recipe, generously. The factor grows faster than the tin because area goes with the square of the width. A 12 inch tin has four times the area of a 6 inch tin, not twice.
Rounding the factor to the eggs
Eggs set the practical factor. If the recipe uses 3 eggs and the factor is 0.56, use 2 eggs, which makes your true factor 0.67, and scale everything else by 0.67. The cake will be slightly taller. If it uses 2 eggs, a factor of 0.56 rounds neatly to 1 egg and exactly half the recipe. Our page on halving and doubling has the spoon and cup arithmetic.
If you would rather not change the recipe
You can pour the original recipe into a different tin if you follow two rules.
- Fill the tin only half to two-thirds full. Bake any extra batter as cupcakes.
- Adjust for depth. In a smaller tin the batter is deeper: lower the oven by about 10 to 15 °C and bake longer, so the centre cooks before the top darkens. In a larger tin the batter is shallower: keep the temperature and start checking much earlier.
Baking time when the tin changes
No table can give exact minutes, because ovens differ. Use the recipe's time as a guide and test the cake itself:
- the top springs back when pressed lightly;
- the cake has just begun to pull away from the sides of the tin;
- a thin skewer or toothpick pushed into the centre comes out clean, with no wet batter.
Start testing about ten minutes before the stated time for a shallower cake, and expect ten to twenty minutes more for a deeper one. Do not open the oven in the first two-thirds of the baking time, or the cake may sink.
Measuring a tin
Measure across the inside of the top, from inner edge to inner edge. Tins in India are sold by inches, and a "half kg cake tin" is usually 6 inches across while a "1 kg tin" is usually 8 inches. Those names describe the finished, iced cake a bakery would sell, not the weight of batter, so go by the measurement.
Depth matters as well. Most recipes assume a tin about 2 to 3 inches (5 to 7.5 cm) deep. In a shallower tin, use less batter.
Other vessels
- Pressure cooker or kadhai baking: the tin must sit inside with a finger's width of space all round, which usually means a 6 or 7 inch tin. Scale the recipe to fit that tin.
- Glass dishes heat slowly and hold heat. Lower the oven by about 10 °C.
- Dark tins brown faster than shiny ones. Check early.
- Ring (bundt) tins bake faster than their size suggests, because heat reaches the centre through the tube.
Oven settings in Celsius, Fahrenheit and gas mark are on the oven temperatures page.
Questions people ask
Can I use a square tin instead of a round one?
Yes. Use a square tin about one inch smaller than the round tin: a 7 inch square for an 8 inch round recipe.
How do I convert an 8 inch cake recipe to a 6 inch tin?
Multiply every ingredient by 0.56, a little over half. If the recipe has 2 eggs, simply make half the recipe.
How full should a cake tin be?
Half to two-thirds full. The batter needs room to rise.
What size is a 1 kg cake tin?
Usually about 8 inches across, but the name refers to the finished bakery cake, so measure the tin itself.
More kitchen help
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- Spice namesJeera, ajwain, kalonji: English and Hindi names with uses.
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- Recipe words explainedAbbreviations and cooking words, with Hindi kitchen words.
- Reheating leftoversCooling, storing, thawing and reheating, from official guidance.
- Safe cooking temperaturesOfficial minimum temperatures for chicken, meat, fish, eggs.