Swap baking pans.

The recipe wants a 9×13 and you own an 8×8. Here’s the multiplier, what it does to the batter depth, and how the timing shifts.

Swap thefor

69%

Multiply every ingredient by 0.69 to fill the 9" × 9" square to the same depth.

Workable, but scale the ingredients or accept a different depth and bake time. The new pan is smaller, so the batter sits deeper and bakes slower. Add roughly 5–10 minutes and test the centre before pulling it. Unscaled, the batter sits 44% deeper (117 to 81 square inches).

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Baking pan sizes by area

Base area in square inches: the number that decides how deep the batter sits, and so how it bakes.

Baking pan sizes with their base area in square inches
Pan	Area	Shape
6" round	28.3 in²	Round
7" round	38.5 in²	Round
8" round	50.3 in²	Round
9" round	63.6 in²	Round
10" round	78.5 in²	Round
8" × 8" square	64 in²	Square
9" × 9" square	81 in²	Square
9" × 13" rectangular	117 in²	Rectangular
11" × 7" rectangular	77 in²	Rectangular
8½" × 4½" loaf	38.3 in²	Loaf
9" × 5" loaf	45 in²	Loaf
9" springform	63.6 in²	Specialty
10" springform	78.5 in²	Specialty
10" bundt (12-cup)	78.5 in²	Specialty
Quarter sheet (9" × 13")	117 in²	Rectangular
Half sheet (13" × 18")	234 in²	Rectangular

Swaps that need no change

9″ round and 8″ square, within 1%
10″ round and 9″ square, within 4%
9″ springform and 9″ round, the same base
Quarter sheet and 9″ × 13″, the same pan

The material matters too

Glass and dark metal hold more heat than light aluminium, so edges brown faster and the bake finishes sooner. Drop the oven about 10 °C for glass or a dark non-stick tin. The area conversion assumes you aren’t also changing material.

Scaling the ingredients

Once you have the multiplier, paste the ingredient list into the recipe scaler and enter it there. It gives back fractions instead of the 0.55-cup arithmetic you’d otherwise do at the counter.

Real recipes, other pans.

Three published recipes moved to a tin you might own, worked through with the areas above.

Slices of cranberry loaf cake with a cream cheese centre, from Mediterranean Recipes 2026’s reel

Cranberry cream cheese loaf cake

Recipe from Mediterranean Recipes 2026, from their Instagram reel. Baked in a 9 × 5-inch loaf pan.

In an 8½" × 4½" loaf85% of everything
Multiply each amount by0.85
Unscaled, it sits17% deeper

Open the recipe

Salmon fillets, Boursin and cherry tomatoes in a red baking dish, from Carman Wilken’s reel

Boursin salmon bake

Recipe from Carman Wilken, from her Instagram reel. Baked in a 9 × 13-inch dish.

In a 9" × 9" square69% of everything
Multiply each amount by0.69
Unscaled, it sits44% deeper

Open the recipe

Cabbage rounds topped with beef and melted mozzarella in a baking dish, from quotidian recipes’ reel

Oven-baked cabbage burgers

Recipe from quotidian recipes, from their Instagram reel. Baked in a 9 × 13-inch dish.

In an 8" × 8" square55% of everything
Multiply each amount by0.55
Unscaled, it sits83% deeper

Open the recipe

Keep the recipes you bake in one place.

ReelsMeals turns saved Reels, TikToks, YouTube videos and photos of paper recipes into cards you can search by ingredient, each linked to the original.

Try one reel Browse recipes

Common questions

Can I use an 8×8 pan instead of a 9×13?

Only with the recipe scaled down. A 9×13 has 117 square inches of base and an 8×8 has 64, about 55% of the area. Pour the full recipe into the smaller pan and the batter sits nearly twice as deep, so the edges set long before the centre. Scale the ingredients to 55% and the bake behaves normally.

How do I work out pan conversions myself?

Compare base areas. For a rectangular pan multiply length by width; for a round one use π times the radius squared. Divide the area of the pan you have by the area the recipe calls for, and that ratio is your ingredient multiplier. Depth is what changes how a bake behaves, and area sets the depth.

Is a 9-inch round the same as an 8-inch square?

Very nearly, which is why they’re the classic swap. A 9-inch round is 63.6 square inches and an 8-inch square is 64, under 1% apart. Use either without touching the recipe.

How much does the bake time change?

As a rule of thumb, deeper batter needs more time at a slightly lower temperature, and shallower batter needs less time at the stated temperature. If you go much deeper, dropping the oven by 10–15 °C stops the outside setting before the middle catches up. Test the centre rather than trusting a converted time.

How full should I fill a cake tin?

Two-thirds at most. Cake batter rises, and a tin filled higher will dome and crack or spill over. If the conversion asks for more than that, use a taller tin or split the batter between two.

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