9x13 to Half Sheet Pan Conversion
A half sheet pan has roughly 1.6 to 2 times the floor of a 9×13, but its walls are only about 1 inch tall. For most cakes, 1.5 times a 9×13 recipe is the safer conversion; a full double can climb too close to the rim.
- 4 min read
- Updated 2026-11-03
Printable chart
Use your browser’s Print command for this chart and your scaled ingredient list.
| Half sheet inside size | Inside area | Area vs. 9×13 | Batter depth at 1.5× | Batter depth at 2× | Back to 9×13: multiply by |
|---|---|---|---|---|---|
| 18×13 in (rim to rim) | 234 sq in | 2 | 75% | 100% | 0.5 |
| 17×12 in | 204 sq in | 1.74 | 86% | 115% | 0.57 |
| 16½×11½ in | 189.75 sq in | 1.62 | 92% | 123% | 0.62 |
Batter depth is relative to how deep the batter sat in the 9×13. The 18×13 row uses rim-to-rim measurements and overstates the baking surface; measure the flat inside of your own pan.
Scale your ingredients
Paste your 9×13 recipe into the scaler below. It starts at 1.5; change it to suit your measured pan, or enter the last chart column’s number to bring a half-sheet recipe down to a 9×13.
Measure the inside, not the label
“Half sheet” names a family of pans about 18 by 13 inches from rim to rim. The flat baking surface inside is smaller, and can be closer to 16½ by 11½ inches once the rolled edge and sloped walls are taken out. A 9×13 cake pan, by contrast, measures close to 9 by 13 inside. Multiply inside length by width for each pan and divide: a 17×12 interior gives 204 ÷ 117 = 1.74.
Wall height is the real limit
A typical 9×13 cake pan is about 2 inches deep; a half sheet is about 1 inch. Batter that sat ¾ inch deep in the 9×13 would still sit ¾ inch deep in a true 2:1 half sheet if you doubled the recipe, leaving only ¼ inch to rise before it reaches the rim. At 1.5 times, the same batter sits about 0.56 to 0.69 inch deep across the chart’s three sizes, which leaves more headroom. That is why the scaler above starts at 1.5 rather than 2.
When a full double works
Bars, brownies and thin sheet cakes that rise very little can often take a double batch in a half sheet, especially if the 9×13 version was shallow. Pour the batter and look: if it comes more than about two-thirds of the way up the rim, hold some back for a few cupcakes. Fluffy butter cakes and recipes with a lot of baking powder need the extra room.
Is a 9×13 a quarter sheet?
Close in footprint, not in depth. A quarter sheet pan is about 13 by 9 inches across the rim with walls about 1 inch tall, so it has a little less flat surface than a 9×13 cake pan and about half the depth. A cake recipe written for a 9×13 can overflow a quarter sheet, while a quarter-sheet recipe for cookies or roasted vegetables works fine in a 9×13. Bakery “quarter sheet cakes” are a separate matter: shop sizes vary, so ask for the dimensions when ordering. To scale between a half sheet and a quarter sheet, use the half sheet to quarter sheet guide.
Baking a thinner sheet cake
Keep the recipe’s temperature. A half-sheet layer is usually thinner than the 9×13 version, so it tends to bake faster; begin checking about 10 minutes before the recipe’s earliest time and use its doneness cues rather than a fixed reduction. Turn the pan halfway through if your oven heats unevenly, and make sure it fits with space around it for air to move. The top is 1.6 to 2 times larger, so plan on that much more frosting; the frosting calculator can help.
Frequently asked questions
How much should I scale a 9x13 recipe for a half sheet pan?
Start with 1.5 times for cakes. A half sheet usually has 1.6 to 2 times the floor of a 9x13, but its walls are about half as tall.
Can I double a 9x13 recipe in a half sheet?
Sometimes for bars and brownies that rise little, but doubled cake batter can reach the 1-inch rim before it rises.
Is a 9x13 pan a quarter sheet pan?
Not quite. They have a similar footprint, but a 9x13 cake pan is about twice as deep as a quarter sheet.
How do I convert a half sheet recipe to a 9x13?
Multiply by about 0.5 to 0.62, depending on your half sheet’s inside area. The 9x13’s taller walls give extra headroom.