★ FOOD · BAKING · REFERENCE TABLES
A 9 × 13 in pan is 117 sq in — and it is its own nearest standard pan, scaling factor 1.00. Enter any pan's dimensions to find its area, the closest standard pan, and the factor for scaling a recipe into it.
Recipes are written for a pan size, and swapping pans without scaling the batter is how cakes overflow or bake dry. This calculator finds your pan's area, matches it to the nearest standard pan in the chart, and gives you the scaling factor — nearest area divided by your pan's area.
Area is what matters when you swap pans, not the shape name. A rectangle's area is length times width; a round pan's area is π times radius squared. That is why a 9-inch round pan (63.6 sq in) is nearly the same batter capacity as an 8-inch square (64 sq in), even though the two pans look nothing alike. The chart below lists the ten standard pans this calculator matches against, smallest first.
| Pan | Dimensions | Area (sq in) | Closest swap |
|---|---|---|---|
| Loaf | 8 x 4 in | 32 | 9 x 5 loaf (45 sq in) |
| Loaf | 9 x 5 in | 45 | 8-in round (50.3 sq in) |
| Round | 8-in diameter | 50.3 | 9 x 5 loaf (45 sq in) |
| Round | 9-in diameter | 63.6 | 8 x 8 square (64 sq in) |
| Square | 8 x 8 in | 64 | 9-in round (63.6 sq in) |
| Round | 10-in diameter | 78.5 | 9 x 9 square (81 sq in) |
| Square | 9 x 9 in | 81 | 10-in round (78.5 sq in) |
| Round | 12-in diameter | 113.1 | 9 x 13 rectangle (117 sq in) |
| Rectangle | 9 x 13 in | 117 | 12-in round (113.1 sq in) |
| Half-sheet | 13 x 18 in | 234 | Two 9 x 13 pans (234 sq in combined) |
Matching area gets the batter amount right, but depth is the second half of a pan swap. A shallower pan spreads the same batter thinner, so it bakes faster and can dry out; a deeper pan holds it thicker, so the middle needs more time and can stay underdone while the edges set. Keep the batter depth within about half an inch of the original pan's depth, or adjust the baking time — start checking a shallower pan 5 to 10 minutes early, and give a deeper pan extra time with a foil tent if the top browns first. As a rule of thumb, never fill any pan more than two-thirds full: batter rises, and a pan matched on area but filled to the brim will still overflow.
| Output | Formula | What it means |
|---|---|---|
| Rectangle area | Length × width | 9 × 13 = 117 sq in at the defaults. |
| Round area | π × (diameter ÷ 2)² | π × 5² = 78.5 sq in for a 10-in round. |
| Nearest standard pan | Smallest |area − chart area| | 117 sq in matches the 9 x 13 in pan itself. |
| Scaling factor | Nearest area ÷ your pan area | 117 ÷ 117 = 1.00 at the defaults; 63.6 ÷ 64 = 0.99 for an 8 x 8 in pan. |
Areas here are the inside dimensions of standard pans, rounded to one decimal for round pans; real pans vary by a few percent by brand, and sloped sides make the top area larger than the bottom area. The calculator matches on area alone, so it cannot see depth: a 9 x 13 pan that is 2 inches deep and a 12-in round that is 3 inches deep hold the same area of batter at different depths, and the bake time will differ. Volume, not area, is the exact measure for very deep or very shallow pans — multiply area by depth when depth differs by more than half an inch. Treat the scaling factor as the batter adjustment, then watch the bake, not the clock.
Bright Side Kit. "Baking Pan Size Chart: Area, Substitutions & Scaling." https://brightoolbox.com/baking-pan-size-chart/ Accessed October 24, 2026.117 square inches: 9 times 13. It is the most common rectangular cake pan, and it matches a 12-in round pan (113.1 sq in) closely enough for most recipes.
Yes — they are nearly identical in area: 64 sq in for the square against 63.6 sq in for the round, a scaling factor of 0.99. Use the recipe as written and check the bake a few minutes early.
An 8-in round pan is the closest standard swap: 50.3 sq in against 45 sq in, a scaling factor of 1.12. Multiply the recipe by 1.12, or accept a slightly thinner bake with the recipe as written.
Divide the new pan's area by the recipe pan's area to get the scaling factor, then multiply every ingredient by it. A factor of 1.12 means 12% more of everything; a factor of 0.99 means essentially no change.
Most likely depth, not area: the new pan held the batter deeper, or you filled it past two-thirds full. Match area first, then keep batter depth within about half an inch of the original, and never fill a pan more than two-thirds full.
Yes. Thinner batter sets faster, so start checking a shallower swap 5 to 10 minutes before the recipe's time. A deeper pan needs the opposite: more time, and a foil tent if the top browns early.
78.5 square inches: π times 5 squared (78.54, rounded to one decimal). Its closest standard swap is the 9 x 9 in square at 81 sq in, scaling factor 1.03.
Exactly, by area: 13 times 18 is 234 sq in, which is twice 117 sq in. Doubling a 9 x 13 recipe into a half-sheet gives the same batter depth if both pans are the same depth.