9×13 to 8×8
pan conversion.

Why 0.55×, not 0.5×

The 9×13 is not exactly twice the area of an 8×8. The exact ratio is 64 ÷ 117 = 0.547, which rounds to 0.55. Using 0.5× would give you slightly too little batter, and the result would be shallower and potentially dry at the edges. Use 0.55 for accuracy — or simply use Servings mode if the 9×13 recipe specifies a serving count and you want to scale to a proportional number of servings.

Bake time and temperature

The 8×8 holds the same batter volume in a smaller footprint — the batter sits about 80% deeper than in the 9×13. Heat must travel further to reach the center, so bake time increases. Start by adding 10 minutes and checking doneness. For dense items like brownies or bar cookies, the center can easily be underdone while the edges are perfect — a toothpick test or probe thermometer (195°F / 90°C for brownies, 200°F / 93°C for cakes) is the most reliable method.

Reduce the oven temperature by 25°F / 15°C to compensate for the deeper pan — this slows the top browning while the center catches up.

What the 8×8 is good for

The 8×8 is the standard half-batch pan for brownies, bar cookies, sheet cakes, casseroles, and rice dishes. It's a versatile size that fits most home ovens alongside another pan. The slightly deeper result from the 0.55× conversion often produces a fudgier brownie or moister cake than the original 9×13 version — which many bakers prefer.

Going the other way: 8×8 to 9×13

To scale an 8×8 recipe up to a 9×13, use a scale factor of 1.83× (117 ÷ 64). This isn't far from doubling — using 2× is an acceptable shortcut if you want to avoid awkward fractions, accepting that the batter will be a little shallower and the bake time about the same as the original. For baked goods where exact texture matters, stick to 1.83×.

Frosted, glazed, and layered items: cutting and serving differences

The shape of the finished bake matters for service. A 9×13 typically yields 12–20 rectangular pieces depending on the cut; an 8×8 yields 9–16 pieces. If you're converting a brownie recipe for a different number of portions, recalculate the cut grid rather than adjusting the recipe. A 9×13 cut 4×5 gives 20 pieces; an 8×8 cut 3×3 gives 9. The 0.55× scale factor ensures each piece is roughly the same thickness and size across both formats, which matters for catering or event baking where portion consistency is expected.