Converting 10-Cup Bundt Cake to 9×13 Rectangle Pan
When converting a 10-cup Bundt pan recipe to a 9×13 rectangular pan, multiply all ingredients by 1.09. This accounts for the nearly identical volumes: a 10-cup Bundt holds approximately 10 cups (2.4 liters), while a 9×13 pan holds 10.9 cups when half-filled. However, the conversion requires critical adjustments: reduce oven temperature by 25°F and decrease baking time by 35-40% because removing the center tube dramatically changes heat distribution.
Quick Conversion Reference
- Ingredient multiplier: ×1.09 (all ingredients)
- Temperature: Original temp -25°F (e.g., 350°F → 325°F)
- Time: Original time ×0.6 to ×0.65 (much faster without tube)
- Key difference: No center tube = thinner layer + less even heating
Why Bundt to Sheet Conversion is Unique
This isn't a simple pan swap—it's a fundamental change in baking physics. Understanding these differences is crucial for success.
The Center Tube Factor
10-Cup Bundt Pan (With Tube)
- Volume: 10 cups (2.4L)
- Heat sources: Outside + inside (center tube)
- Batter depth: ~2-2.5 inches (thick ring)
- Baking: Dual heat penetration = faster, even cooking
- Advantage: Center tube conducts heat to middle
9×13 Rectangle (No Tube)
- Volume: 10.9 cups (2.6L half-filled)
- Heat sources: Bottom + top only
- Batter depth: ~1 inch (thin, wide layer)
- Baking: Heat travels from edges to center
- Challenge: Edges cook faster than center
⚠️ Critical Insight:
Bundt pans cook from both outside AND inside simultaneously. When you remove the center tube, you lose 50% of your heat conductivity. This is why we reduce both temperature (prevent edge burning) and time (thinner layer cooks faster from top/bottom).
Volume Comparison
| Pan Type | Capacity | Typical Fill | Batter Depth |
|---|---|---|---|
| 10-cup Bundt | 10 cups (2.4L) | 6-7 cups | 2-2.5 inches |
| 9×13 Rectangle | 14 cups (3.3L) | 7 cups (half) | ~1 inch |
Multiplier calculation: 7 ÷ 6.5 (average Bundt fill) = 1.08 ≈ 1.09
Temperature & Time: The Double Adjustment
Unlike most conversions that change only time OR temperature, Bundt-to-sheet requires adjusting BOTH factors.
Why Reduce Temperature?
Problem Without Adjustment:
If you use the original Bundt temperature (e.g., 350°F) in a 9×13 pan:
- • Edges brown too fast (exposed to direct pan heat)
- • Center stays raw (no tube to conduct heat)
- • Top cracks (too-rapid surface setting)
Solution: Drop temp by 25°F to slow edge browning while center cooks through.
Why Drastically Cut Time?
The Thin Layer Effect:
Bundt: 2.5-inch thick ring → Heat travels 1.25 inches to center
9×13: 1-inch flat layer → Heat travels only 0.5 inches to center
Result: Heat reaches the middle in 60% of the time, even with the center tube removed.
Conversion Chart
| Original Bundt | Converted 9×13 | Cake Type |
|---|---|---|
| 325°F for 50 min | 300°F for 30-32 min | Delicate pound cake |
| 350°F for 45 min | 325°F for 27-30 min | Standard Bundt (vanilla, lemon) |
| 350°F for 55 min | 325°F for 33-36 min | Dense cakes (chocolate, spice) |
Step-by-Step Conversion Process
Step 1: Multiply Ingredients by 1.09
Original 10-Cup Bundt:
- 3 cups (375g) flour
- 2 cups (400g) sugar
- 1 cup (227g) butter
- 4 eggs
- 1 cup (237ml) sour cream
- 1 tbsp baking powder
- 1 tsp vanilla
Converted 9×13:
- 3¼ cups (409g) flour
- 2⅛ cups (436g) sugar
- 1⅛ cups (248g) butter
- 4⅓ eggs (or 218g)
- 1⅛ cups (258ml) sour cream
- 1⅛ tbsp baking powder
- 1⅛ tsp vanilla
Step 2: Reduce Temperature by 25°F
Bundt recipe at 350°F? Bake at 325°F.
Bundt recipe at 325°F? Bake at 300°F.
This compensates for the loss of the center tube's heat conduction.
Step 3: Cut Time by 35-40%
Original Bundt: 45 minutes → Start checking at 27 minutes
The Edge-Check Method:
- 1. Insert toothpick in CENTER (slowest spot)
- 2. Also check 2 inches from each EDGE
- 3. Center should come out with few moist crumbs
- 4. Edges should be set but not dry
Real Recipe Conversion Example
Example: Classic Lemon Bundt to Sheet Cake
Original Bundt (350°F, 50 min):
- 3 cups (375g) all-purpose flour
- 2½ cups (500g) sugar
- 1 cup (227g) butter, softened
- 4 large eggs
- 1 cup (237ml) buttermilk
- ¼ cup (60ml) lemon juice
- 2 tbsp lemon zest
- 1 tbsp baking powder
- ½ tsp baking soda
- ½ tsp salt
Converted 9×13 (325°F, 30-33 min):
- 3¼ cups (409g) flour
- 2¾ cups (545g) sugar
- 1⅛ cups (248g) butter
- 4⅓ eggs (or 218g beaten)
- 1⅛ cups (258ml) buttermilk
- ¼ cup + 1 tsp (65ml) lemon juice
- 2⅛ tbsp lemon zest
- 1⅛ tbsp baking powder
- ½ tsp + ⅛ tsp baking soda
- ½ tsp + ⅛ tsp salt
Presentation tip: Bundt cakes look dramatic with glaze dripping down fluted sides. For 9×13 sheet cakes, consider a lemon cream cheese frosting spread evenly, or keep it simple with a dusting of powdered sugar.
Common Bundt-to-Sheet Problems
Problem: Dry Edges, Gooey Center
Classic symptom of not reducing temperature enough.
Solutions:
- • Reduce temp by FULL 25°F (not 15°F)
- • Use light-colored metal pan, not dark/glass
- • Cover edges with foil strips after 20 minutes
- • Rotate pan 180° halfway through baking
Problem: Cake Sinks in Middle
Usually from opening oven too early or undermixing.
Solutions:
- • Don't open oven until minimum time (e.g., 25 min)
- • Verify baking powder/soda are fresh (test in water)
- • Ensure butter and eggs are room temperature
- • Mix batter just until combined (don't undermix)
Problem: Tough, Dense Texture
Bundt cakes are often rich and tender. Sheet version can turn tough.
Solutions:
- • Don't overbake (check at 60% of Bundt time)
- • Don't overmix batter after adding flour
- • Add 1-2 tbsp extra sour cream or oil for moisture
- • Let cool in pan 15 min, then cover with foil to retain moisture
When NOT to Convert Bundt to Sheet
Some Bundt recipes rely on the pan's unique shape for more than just aesthetics.
❌ Not Recommended:
- Tunnel of Fudge cakes: Need center tube for molten center
- Extremely dense pound cakes: Require dual heat penetration
- Show-stopping designs: Bundt's fluted pattern is the point
✅ Perfect For:
- Casual gatherings: Sheet cakes serve more easily
- Potlucks: Easier to transport rectangular pans
- Frosted cakes: Flat surface better for decorating
Related Pan Conversions
Frequently Asked Questions
Can I go the opposite direction (9×13 to Bundt)?
Yes, but it's trickier. Divide ingredients by 1.09, INCREASE temp by 25°F, and ADD 35-40% more time. The center tube requires longer baking to cook the thick ring of batter.
What about 12-cup Bundt pans?
12-cup Bundt to 9×13 requires multiplying by 0.91 (slightly LESS ingredients). Same temperature and time adjustments apply. Most recipes are better suited to a larger 11×15 inch pan for 12-cup Bundts.
Why not just fill the Bundt pan less?
You could, but Bundt pans are designed to showcase their shape. An underfilled Bundt looks sad and doesn't benefit from the fluted design. Better to convert to a pan that shows off a flat-topped cake properly.