Pan size
converter.
Pick your original and target pans — or enter custom dimensions — and get the exact scale factor for your recipe.
Pan size calculator
How the scale factor is calculated
The scale factor is simply the ratio of the two pan areas. For rectangles and squares, area = length × width. For round pans, area = π × (diameter ÷ 2)². Multiply every ingredient quantity in your recipe by the scale factor, then adjust bake time based on how the batter depth changes.
Bake time and depth
Bake time depends primarily on batter depth, not volume. A smaller pan concentrates the same batter into a deeper layer — heat takes longer to reach the center. When scaling down (factor < 1), add 10–20 min and check with a probe thermometer. When scaling up (factor > 1), the batter is shallower — reduce time by 5–15 min and check early. Keep temperature the same unless depth changes dramatically, then consider reducing by 25°F / 15°C.
Why pan material affects the result
The scale factor only accounts for pan area — it doesn't account for material. Dark metal pans absorb heat faster than light-coloured aluminium, so a swap from a light round pan to a dark square pan of the same area will still brown the edges faster. Glass and ceramic bakeware conducts heat more slowly than metal: a glass 9×9 runs about 25°F / 15°C cooler than an equivalent metal pan, and takes 10–15 minutes longer to fully bake a cake. If your pan swap also involves a material change, adjust the temperature accordingly: reduce by 25°F for dark non-stick, reduce by 25–50°F for glass or ceramic.
When the area method doesn't apply
Area-based scaling works well for most cakes, brownies, bar cookies, and casseroles where batter depth is the main variable. It works less well for Bundt cakes (where the tube creates uneven heat distribution that the area formula can't capture) and for very tall or deep items like angel food cakes or cheesecakes in springforms (where side-wall conduction matters as much as base area). For Bundt substitutions, use the pan's volume capacity rather than its base area. For very deep items, stick to pans with the same diameter and depth as specified; the recipe was likely tested specifically for that geometry.
Lining pans after a substitution
Pan substitutions sometimes require a lining approach different from the original recipe. Round pans are easily lined with a parchment circle cut to fit the base. Square and rectangular pans are best lined with a parchment sling — two strips laid perpendicular, overhanging all four sides — so the finished bake can be lifted out cleanly for slicing. Loaf pans benefit from a sling too. If you're moving from a springform (which releases the sides mechanically) to a standard square pan, grease the sides well and consider a full parchment lining to ensure clean release, especially for cheesecakes or other delicate bakes.
Common pan areas
Base area in square inches and approximate batter capacity at 2 inches deep.
| Pan | Area (sq in) | Capacity |
|---|---|---|
| 6-inch round | 28 | 4 cups |
| 8-inch round | 50 | 6 cups |
| 9-inch round | 64 | 8 cups |
| 10-inch round | 79 | 11 cups |
| 8×8 square | 64 | 8 cups |
| 9×9 square | 81 | 10 cups |
| 9×13 rectangle | 117 | 14 cups |
| 10×15 jelly roll | 150 | 16 cups |
| 8½×4½ loaf | 38 | 6 cups |
| 9×5 loaf | 45 | 8 cups |
| 9-inch springform | 64 | 10 cups |
| 10-inch Bundt* | ~79 | 12 cups |
*Bundt area is approximate — use capacity as a guide instead.
Frequently asked questions
- What pan can I substitute for a 9×13?
- Two 9-inch round pans are the closest substitute for a 9×13 pan — their combined area (128 sq in) is nearly equal to a 9×13 (117 sq in), so the scale factor is close to 1.0. An 8×8 uses a 0.55× scale factor, meaning deeper batter and longer bake time.
- How do I convert a 9-inch round recipe to an 8×8 pan?
- A 9-inch round has 64 sq in of base area; an 8×8 square also has 64 sq in — the scale factor is exactly 1.0. Use the same ingredient quantities and the same bake time.
- Does changing pan size affect bake time?
- Yes. Bake time depends primarily on batter depth, not total volume. A smaller pan concentrates batter deeper — add 10–25 min and use a probe thermometer. A larger pan spreads batter shallower — reduce time by 5–20 min and check early.
- How do I calculate a pan substitution scale factor?
- Divide the target pan's base area by the original pan's base area. For rectangles, area = length × width. For round pans, area = π × (diameter ÷ 2)². Multiply every ingredient quantity by this factor.
Scale your recipe to the new pan
Once you have your scale factor, paste your ingredient list and apply it — all quantities update instantly with clean kitchen fractions.