# Cake Pan Size Converter Convert a recipe between baking pans by base area, so the batter sits at the same depth and the bake time stays close. --- - **Canonical URL:** https://dothecalculation.com/calculators/cake-pan-size-converter - **Category:** Hobbies & Leisure Utilities - **Publisher:** Do The Calculation (https://dothecalculation.com) - **Cost:** Free, no account or sign-up required - **Privacy:** Runs entirely in the browser; inputs are never sent to a server - **Methodology:** https://dothecalculation.com/methodology --- ## Use the pan you have, not the one the recipe wants Enter the pan a recipe calls for and the pan in your cupboard, and this works out how much to scale the recipe so the batter sits at the same depth. Base area is what matters, and it is the thing most conversions get wrong. - Round, square, rectangular, loaf, tube and bundt - Handles multiple tins: two 6-inch layers into one 8-inch - Scales by base area, so the bake time stays close ## Quick answer To move a recipe between pans, **scale it by the ratio of the base areas**, not by the ratio of the volumes. Base area decides how deep the batter sits, and depth is what drives bake time. Keep the depth the same and the original time and temperature stay roughly right; change the depth and they do not. Three swaps worth knowing, all of which this calculator produces from the dimensions rather than from a lookup table: • An 8-inch square and a 9-inch round are within 1% of each other. Swap them straight across. • Going from an 8-inch round to a 9-inch round needs about 27% more batter. • A 9×13 inch pan has about 84% more base area than a single 9-inch round, so a single-layer recipe needs almost doubling. ## Why area rather than volume This is the part that trips people up, and it is worth thirty seconds of thought because it changes the answer. Suppose a recipe fills an 8-inch round tin two inches deep and you want to use a 9-inch round of the same depth. By volume the pans differ by 27%, and by area they also differ by 27%, so either answer works. The two only agree because the pans are the same depth. Now suppose your 9-inch tin is three inches deep. By volume it holds 90% more, so scaling by volume means nearly doubling the recipe — and you would get a cake half as tall again as the original, baking far more slowly in the middle. By area it still needs only 27% more, and the batter sits at the original two inches. The second answer is the one you want. The rule of thumb: **scale by area to keep the cake the same, scale by volume to fill the pan.** For cakes, brownies and traybakes you almost always want the first. ## What changes besides the quantity Bake time. Even at the same batter depth, a wider pan has more edge relative to its middle and tends to finish sooner. Start checking about 20% earlier than the recipe says, and go by a skewer rather than by the clock. Oven temperature. If the batter ends up noticeably deeper than the original, dropping the oven by 15 to 25 °F and baking longer helps the middle set before the outside dries. If it ends up shallower, leave the temperature alone and just check sooner. How full to fill. Cake batter is usually filled to between half and two thirds of the pan height so it has room to rise. If a conversion asks you to fill a pan much fuller than that, split it across two pans instead. Structure. Scaling a delicate sponge a long way changes how it holds together, and a very thin layer in a very wide pan can dry out before it colours. Big jumps are better done as two batches than as one large one. ## Measuring the pans properly Measure across the **inside** of the rim, not the outside, and measure the depth on the inside too. On a tapered tin, measure the base rather than the top, since the base is what the batter sits on. Bundt and tube pans are the awkward case. They are fluted and sloped, so the cylinder their outside dimensions describe holds more than the pan does. The capacity figure this page gives for them is an upper bound. The reliable method is to fill the pan with water a cup at a time and count; that number is worth writing on a label taped to the tin. ## Worked examples Every figure below comes from the calculator, using base area. | Recipe calls for | You have | Scale by | Base area change | |---|---|---|---| | 8 in round | 9 in round | 1.27× | +27% | | 9 in round | 9 × 13 in | 1.84× | +84% | | 8 in square | 9 in round | 0.99× | −1% | | Two 6 in rounds | One 8 in round | 0.89× | −11% | That last row is the one people get wrong most often. Two 6-inch tins have more base area between them than a single 8-inch tin, so a two-layer recipe baked as one 8-inch cake needs scaling **down**, not up. ## Scaling the ingredients afterwards Once you have the multiplier, the [recipe scaler](/calculators/recipe-scaler-calculator) applies it to a whole ingredient list and returns kitchen fractions rather than decimals, flagging the ingredients that resist straight multiplication — leavening, salt, strong spices and eggs. For bread rather than cake, where everything is expressed against flour weight instead of against a pan, the [baker’s percentage calculator](/calculators/bakers-percentage-calculator) is the right tool. ## Frequently asked questions ### Can I use a 9x13 pan instead of two 9-inch rounds? Close, but not exact. Two 9-inch rounds have about 127 square inches of base between them against roughly 117 for a 9×13, so the traybake version comes out slightly deeper. Bake it a little longer and check with a skewer. ### Is an 8-inch square the same as a 9-inch round? Within about 1%, yes. 8×8 is 64 square inches and a 9-inch round is 63.6. It is the safest swap in baking and needs no change to the recipe. ### How much bigger is a 9-inch round than an 8-inch? About 27% more base area, because area goes with the square of the diameter. An inch of diameter is a larger change than it sounds. ### Do I change the oven temperature when I change pan? Only if the batter ends up noticeably deeper. Deeper batter benefits from 15 to 25 °F lower and a longer bake so the middle sets. At the same depth, leave the temperature alone and just start checking earlier. ### How full should I fill a cake pan? Between half and two thirds of its height, so the batter has room to rise. If a conversion would fill a pan fuller than that, split the batter between two pans. ### Why is my bundt pan capacity wrong? Because its fluting and slope mean it holds less than its outside dimensions suggest. Fill yours with water a cup at a time and use that figure; it is the only reliable way. ## Related concepts - **Base area** — The footprint of the pan. It decides how deep the batter sits and therefore the bake time. - **Batter depth** — Volume divided by base area. Keeping it constant is what keeps a converted recipe behaving. - **Pan capacity** — Base area times depth, usually quoted in cups. Useful for judging how full a pan will be. - **Fill level** — How much of the pan height the batter occupies before baking. Half to two thirds is the usual target. ## Related guides - [How to Double or Halve a Recipe](https://dothecalculation.com/blog/hobby/scaling-recipes-math-guide) — A conversion chart for doubling, halving and thirding, what to do about half an egg, and the four ingredients that will not take a multiplier. ## Related calculators - [Recipe Scale & Multiplier Calculator](https://dothecalculation.com/calculators/recipe-scaler-calculator) — Scale recipe ingredient quantities up or down by any multiplier or exact serving size to cook the perfect portion every time. - [Scale Converter Calculator](https://dothecalculation.com/calculators/scale-converter) — Convert dimensions between drawing, model, and real-world scales instantly using any common scale ratio for accurate results. - [Number Base Converter](https://dothecalculation.com/calculators/base-converter) — Convert whole numbers between binary, octal, decimal, and hexadecimal instantly, with positional-notation and successive-division proofs shown. - [Binary, Hexadecimal, & ASCII Multi-Base Converter](https://dothecalculation.com/calculators/binary-hex-ascii-calculator) — Convert integers and strings between binary, hexadecimal, ASCII, and decimal formats instantly with this free online conversion tool. - [Metal Detector Target Depth Estimator](https://dothecalculation.com/calculators/metal-detector-depth-calculator) — Estimate the maximum target detection depth for your metal detector based on coil size, frequency, and soil mineral type. - [Scuba Diving No-Decompression Limit Calculator](https://dothecalculation.com/calculators/scuba-diving-no-decompression-limit-calculator) — Look up no-stop bottom time for a planned depth on air or nitrox, from the published U.S. Navy air table. --- _Every figure here is geometry applied to the dimensions you enter, so there is no table of standard pan sizes to be out of date. The one approximation is bundt and tube pans, whose fluted shape holds less than their outside dimensions describe; measure yours with water if capacity matters. Bake times and temperature adjustments are guidance rather than arithmetic, so test with a skewer._ --- _Source: [Do The Calculation](https://dothecalculation.com/calculators/cake-pan-size-converter). Quote freely with attribution and a link to this page._