Square baking pan sizes are measured by inside dimensions, with the standard 8x8x2-inch pan holding about 8 cups of batter.
For the full breakdown, see our best Square Baking Pan guide.
Whether you’re doubling a brownie recipe or swapping pans mid-mix, the numbers stamped on the bottom of a pan can lie. Square baking pan sizes look simple — 8×8, 9×9, 10×10 — but the depth and the way you measure change everything. Most recipes expect a specific volume, and a shallow pan stuffed with too much batter spills over your oven floor. Here’s how to read a square pan correctly, match it to your recipe, and know when a swap works.
How Square Pan Sizes Are Measured
Square pan dimensions always refer to the inside of the pan, measured from one inner edge straight across to the opposite inner edge. That number never includes the thickness of the walls or the rim.
If you measure outside edge to outside edge, you’ll overestimate the pan’s true size and likely overfill it.
To measure your own pan correctly:
- Place a ruler or tape measure inside the pan, from the inside edge of one wall to the inside edge of the opposite wall.
- Measure both directions — a warped pan can be slightly off square.
- Measure the depth from the inside bottom to the top rim; this number is as important as the width.
Square Pan Capacity: The Numbers That Matter
The most reliable way to match a pan to a recipe is by volume, not by the name on the label. A 9×9 pan that’s 1.5 inches deep holds far less than one that’s 2 inches deep, even though both are called “9×9.”
These are the standard capacities for square pans at common depths, as compiled by baking references:
| Pan Size (Inside) | Depth | Capacity |
|---|---|---|
| 8 x 8 inches | 1.5 inches | 6 cups |
| 8 x 8 inches | 2 inches | 8 cups |
| 9 x 9 inches | 1.5 inches | 8 cups |
| 9 x 9 inches | 2 inches | 10 cups |
| 10 x 10 inches | 2 inches | 12 cups |
Metric equivalents are also common on manufacturer labels: an 8x8x2-inch pan is roughly 20 x 20 x 5 cm, a 9x9x2 is about 23 x 23 x 5 cm, and a 10x10x2 is close to 25 x 25 x 5 cm.
Substituting Pans Safely
You can swap a square pan for a round one when the batter volume and pan area are close enough — but “close” has limits. An 8×8-inch square pan is commonly treated as the area equivalent of a 9-inch round pan, which is why so many recipes offer that swap.
When you change pan size, the batter’s depth changes, and that changes how the center cooks relative to the edges. A deeper pan means a taller cake that needs a longer bake at a slightly lower temperature. A shallower pan bakes faster and can dry out. Compare the batter volume against the pan’s capacity first, then plan to check the bake 5–7 minutes before the original recipe’s time.
Two more practical limits come up often. And be sure to verify the pan’s depth before assuming all 9×9 pans — or any labeled size — hold the same amount.
FAQs
Can I use an 8×8 pan instead of a 9×9?
Only if you adjust for the smaller capacity. An 8x8x2 pan holds 8 cups while a 9x9x2 holds 10, so you would need to cut the recipe by about 20% or accept a thicker, longer-baking result. Fill the pan no more than two-thirds full to avoid overflow.
Does a 9×9 pan hold exactly 10 cups?
Only at a 2-inch depth. A 9×9 pan that is 1.5 inches deep holds about 8 cups, and a 3-inch-deep version holds roughly 15. Always check the pan’s depth and calculate from there rather than trusting the label alone.
How do I know the inside size of my pan?
Measure from the inside of one wall to the inside of the opposite wall, across the bottom. Do this in both directions, then measure the depth from the bottom to the rim. Ignore the outside dimensions printed on the packaging or the bottom of the pan.
References & Sources
- Joy of Baking. “Pan Sizes.” Standard pan dimensions and capacities for common baking pans.
- Cook’s Info. “Baking Pans by Dimension.” Reference for interior pan sizes and their metric equivalents.
- Sally’s Baking Addiction. “Cake Pan Sizes.” Capacity chart and substitution guidance for square and round pans.