10-Cup Bundt to 9×13 Rectangle:
The Physics Challenge
Center tube = fast, even baking
10 cups (2.4L)
No center = slower center cooking
10.9 cups (2.6L)
Slight increase in ingredients
Major Physics Change: No Center Tube!
Bundt's center tube isn't just decorative—it's a heat conductor
Understanding Bundt Pan Physics
The Center Tube Effect
The tube conducts heat to the center, cooking from both inside and outside simultaneously
Maximum distance from heat is only ~1.5 inches, vs 3+ inches in a rectangle's center
Bundt cakes bake 35-40% faster than solid shapes!
Surface Area Differences
~380 sq inches (including center tube and ridges)
117 sq inches (flat top only)
Less browning, more moisture retention in 9×13
Essential Adjustments for Success
Temperature: Must Reduce
Bundt: 350°F standard
High heat works with center tube cooling
9×13: 325°F necessary
Lower temp prevents edges burning while center cooks
Time: Dramatic Reduction
If Bundt takes 55-60 minutes → 9×13 needs only 32-38 minutes
28 minutes
32-35 minutes
38-40 minutes
Crust & Moisture Changes
Bundt cakes develop a firm, caramelized crust. In 9×13:
- •Less crust formation: Only top surface browns
- •More moisture retention: Less surface area exposed
- •Consider glazing: Bundt's crust holds glaze; 9×13 may need frosting for structure
Pan Converter
Case Study: Lemon Bundt to Sheet Cake
What Worked:
- ✓ Scaling by 1.09 gave perfect volume
- ✓ 325°F prevented over-browning
- ✓ Done in 34 minutes (vs 55 original)
- ✓ Added lemon cream cheese frosting
Key Discovery:
The glaze problem: Bundt's ridges hold glaze beautifully. On flat 9×13, glaze pooled. Solution: Poke holes and do a soak, or use thicker frosting.
Bundt-Specific Pitfalls
❌ Using Bundt timing
"I set the timer for 55 minutes and it was completely overbaked!" Remember: no center tube = MUCH faster baking in 9×13.
⚠️ Expecting the same texture
Bundt's unique shape creates a specific crumb. 9×13 will be moister, less crusty, and more uniform. This isn't wrong—just different!
💡 Forgetting Bundt recipes are often less sweet
Bundt cakes rely on caramelized crust for sweetness. Consider adding 2-3 tbsp sugar or planning for frosting/glaze.