Convert a cake recipe to a different pan size
A recipe written for a 9-inch round tin will overflow an 8-inch one and bake flat in a 9 × 13. This cake pan converter works out the area and volume of any two pans — round, square, rectangular, loaf, bundt, oval or sheet, in inches or centimetres — and gives you the factor to multiply the recipe by, with a note on how the baking time and temperature should change. The classic example: a 9-inch round to an 8-inch round is (8 ÷ 9)² ≈ 0.79, so make about three-quarters of the recipe.
Two ways of scaling are offered. Same batter depth compares the pans’ areas and keeps the cake the same height, which is what you want for layers and most sponges, and keeps the baking time close to the original. Same fill level compares full volumes instead, which suits loaf tins, bundts and deep tins where you simply want the pan filled to the same proportion; the tool then reports how much deeper or shallower the batter will be and what that does to the bake.
Common pans are built in — 6 to 10-inch rounds, 18–23 cm rounds, square tins, 9 × 13, sheet pans, loaf tins and bundts — but any dimension can be typed. Everything is calculated in your browser.
How to use the Cake Pan Size Converter
- Choose inches or cm. Switching converts the numbers already typed.
- Under Recipe pan, pick a common pan from the menu or set the shape, dimensions and depth the recipe calls for.
- Under Pan you have, do the same for your tin.
- Choose Same batter depth (layers, sponges) or Same fill level (loaves, bundts, deep tins).
- Read the factor and the practical fraction (for example ≈ ¾), then scale the ingredients — paste the recipe into the recipe scaler with that factor — and follow the bake-time note.
Cake Pan Size Converter features
Six shapes, any size
Round and springform, square, rectangle and sheet, loaf, bundt/tube/ring (outer diameter with a tube allowance) and oval.
Area and volume of both pans
Shown in square inches or cm², cups and millilitres or litres, with the batter volume at two-thirds full.
Two scaling bases
By area for equal cake height, or by volume for equal fill level, with the resulting change in batter depth reported.
Practical factors
When the factor is within 8 % of a simple fraction — ½, ⅔, ¾, 1¼, 1½, 2 — it is suggested so you can scale with sensible quantities.
Bake-time guidance
Deeper batter: lower the oven and allow longer; shallower: check earlier; bundts bake faster from the tube. Factors above 1.5× prompt a two-layer plan.
Twenty common pans
US and metric rounds, squares, 9 × 13, half and quarter sheets, jelly roll, 9 × 5 and 8½ × 4½ loaves, 2 lb loaf tin, 10-inch bundt and more.
How the conversion works
The area of a round pan is π × (diameter ÷ 2)²; of a square or rectangle, length × width; of an oval, π × half-length × half-width; of a bundt, the outer circle minus the tube (taken as one-fifth of the outer diameter). Multiplying area by depth gives the full volume. The scaling factor is the ratio of the new pan to the recipe pan — areas for same-depth baking, volumes for same-fill baking.
Rectangles are not “equivalent” to rounds by diagonal or by side; only area or volume works. An 8-inch square (64 sq in) holds slightly more than a 9-inch round (63.6 sq in), while a 9-inch square (81 sq in) is 27 % bigger than it.
| Pan | Area | Full volume (2 in / 5 cm deep) |
|---|---|---|
| 6-inch round | 28 sq in · 182 cm² | 3.9 cups · 0.9 L |
| 8-inch round | 50 sq in · 324 cm² | 7.0 cups · 1.65 L |
| 9-inch round | 64 sq in · 410 cm² | 8.8 cups · 2.1 L |
| 20 cm round | 49 sq in · 314 cm² | 6.7 cups · 1.6 L |
| 23 cm round | 64 sq in · 415 cm² | 8.9 cups · 2.1 L |
| 8-inch square | 64 sq in · 413 cm² | 8.9 cups · 2.1 L |
| 9 × 13 inch | 117 sq in · 755 cm² | 16.2 cups · 3.8 L |
| 9 × 5 loaf (2¾ deep) | 45 sq in · 290 cm² | 8.6 cups · 2.0 L |
| 10-inch bundt (3½ deep) | 75 sq in · 487 cm² | 18.3 cups full · about 12 cups usable |
Adjusting the bake
- Same depth, bigger pan: similar time; the larger surface browns faster, so check 5–10 minutes early and tent with foil if needed.
- Deeper batter: drop the oven 10–15 °C (25 °F) and allow 20–30 % longer so the centre sets before the crust darkens. The temperature converter helps with °F ↔ °C.
- Shallower batter (a round recipe spread in a sheet pan) can take as little as half the time.
- Leftover batter bakes well as cupcakes — a standard muffin cup holds about ½ cup (120 ml) and bakes in 18–22 minutes.
- For bread doughs, scale by flour weight with the baker’s percentage calculator instead; dough rises, so pan volume rules differ.
Cake Pan Size Converter FAQ
How do I convert a 9-inch round cake recipe to an 8-inch pan?
Divide the areas: 50.3 ÷ 63.6 = 0.79. Make about three-quarters of the recipe (¾ is within 5 % of the exact factor) and bake for roughly the same time, checking a few minutes early.
Can I use a 9 × 13 pan instead of two 8-inch rounds?
Two 8-inch rounds total 100.5 sq in; a 9 × 13 is 117 sq in, a factor of 1.16. Use the full two-layer recipe, spread it in the 9 × 13 and expect a slightly thinner single-layer cake that bakes a little faster.
What size is a 2 lb loaf tin in inches?
Roughly 8½ × 4½ inches by 3 inches deep (about 21 × 11 × 7.5 cm) and holds about 1.9 litres. A 9 × 5 × 2¾ inch US loaf pan is a close match. Both are listed in the common-pan menu.
How full should I fill a cake pan?
Half to two-thirds for most batters; rich, dense batters can go to three-quarters. The volume read-out shows the batter at two-thirds full so you can compare with the recipe yield.
Does the bundt calculation include the tube?
Yes. The tube is assumed to be one-fifth of the outer diameter, which matches typical 10-inch and 12-cup pans. Bundt cakes also bake faster than their depth suggests because heat reaches the batter from the tube as well.