Convert 9-inch Square to 9-inch Round Pan

Converting 9×9 square to 9-inch round pan? Multiply ingredients by 0.78. Square holds 10 cups, round only 8. Learn why same "9-inch" creates 27% difference.

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Common Baking Conversions

Weight

  • 1 cup all-purpose flour ≈ 125g
  • 1 cup granulated sugar ≈ 200g
  • 1 cup brown sugar ≈ 220g
  • 1 stick butter = 113g
  • 1 large egg ≈ 50g

Volume

  • 1 cup = 237ml = 16 tbsp
  • 1 tbsp = 3 tsp = 15ml
  • 1 fl oz = 30ml = 2 tbsp
  • 1 liter = 4.23 cups
  • 1 gallon = 3.785 liters

Temperature

  • 350°F = 175°C = Gas Mark 4
  • 375°F = 190°C = Gas Mark 5
  • 400°F = 200°C = Gas Mark 6
  • 425°F = 220°C = Gas Mark 7
  • 450°F = 230°C = Gas Mark 8

Pro tip: For accuracy in baking, always prefer weight measurements (grams) over volume measurements (cups).

⚠️ The 9-inch Trap: Don't Use All Your Batter!

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9×9 Square

10 cups

81 square inches

⭕

9" Round

8 cups

63.6 square inches

Only use 78% (multiply by 0.78)

The remaining 22% = perfect for 2-3 bonus cupcakes!

Why Same "9-inch" Creates Different Volumes

The Geometry Truth

  • • Square: 9 × 9 = 81 square inches
  • • Round: π × 4.5² = 63.6 square inches
  • • Difference: 27% less capacity

Visual Comparison

Imagine cutting the corners off your square pan - that's exactly the volume you lose when switching to round. Those four corners represent 2 cups of capacity!

Quick Conversion Guide

Square Recipe ×0.78 Round Pan Extra Batter Use
3 cups flour → 2⅓ cups ⅔ cup for cupcakes
4 eggs → 3 eggs 1 egg for glaze
2 cups sugar → 1½ cups + 2 tbsp Save for topping
1 cup butter → ¾ cup + 1 tbsp Perfect!

Baking Adjustments for Round Pans

🌡️ Temperature

No change needed. Keep at original temperature. Round pans distribute heat evenly.

⏱️ Time

Add 3-5 minutes. Slightly deeper batter in center needs extra time. Start checking at original time.

📏 Even Baking

Better results! No corners means more uniform browning and texture.

Already Mixed Your Batter?

Three Smart Solutions:

Option 1: Cupcake Bonus

Fill round pan 2/3 full. Use extra for 2-3 cupcakes. Bake cupcakes at same temp for 18-20 minutes.

Option 2: Tomorrow's Treat

Store extra batter in fridge (up to 24 hours). Perfect for pancakes or muffins tomorrow!

Option 3: Mini Layer

Have a 4-inch or 6-inch pan? Make a mini version for taste-testing or gifting.

Pro Baker's Secret

"When I convert from square to round, I actually prefer it! The round shape eliminates dry corners, and the slightly thicker center creates a moister crumb. Plus, those 'extra' cupcakes? They're perfect for testing if the cake is good before serving to guests!"

— Sarah Chen, Professional Pastry Chef

Related Conversions:

Reverse Conversion:
Similar Conversions:

Baking Clinic

Problem: Batter overflowing in oven!

Diagnosis: Used 100% of square recipe in smaller round pan. The 27% volume difference caused overflow.

Solution: Immediately: 1) Lower temp by 25°F, 2) Place sheet pan below to catch drips, 3) Open oven briefly to scoop excess. Next time: Use only 78% of ingredients or choose our 9" square to 10" round for same volume.

Problem: Cake sunk in the middle

Diagnosis: Overfilled round pan disrupted proper heat circulation. Round pans need center space for even baking.

Solution: Never fill pans more than 2/3 full. For this conversion, that means using exactly 78% of the square recipe. The math matters!

Problem: Don't have measuring cups for 78%

Diagnosis: Calculating 78% of measurements like '2/3 cup' can be tricky without proper tools.

Solution: Use our Baker's Percentage Calculator or this trick: Make full recipe, weigh total batter, use 78% by weight. Much more accurate!

Frequently Asked Questions

Q: Why does 9-inch square hold more than 9-inch round?

A: The "9 inches" measures different things! Square: 9×9 = 81 square inches of area. Round: π×4.5² = only 63.6 square inches. Those corners in the square add 27% more space. Think of it this way: if you cut the corners off your square to make it round, you'd lose over 2 cups of capacity!

Q: Can I just use a deeper round pan instead?

A: Yes! A 9×3 inch round pan (instead of standard 9×2) gives you 12 cups capacity - even more than the square. This is perfect if you want to keep the full recipe. Find deep pans at restaurant supply stores. Just add 5-10 minutes to baking time for the extra depth.

Q: What if my recipe specifically needs corner pieces?

A: Some recipes (like brownies with crispy edges) rely on corners. For these, stick with square pans or try our reverse conversion. Round pans eliminate corners completely, which changes texture distribution.

Q: Is the 0.78 conversion exact or approximate?

A: It's mathematically exact: 63.6 ÷ 81 = 0.785, rounded to 0.78 for practical use. For most recipes, this precision is perfect. For finicky recipes like soufflés or angel food cakes, weigh your batter and use exactly 78.5% for best results.