Baking Guides

Bundt Pan to Loaf Pan Conversion (Ring-Area Math)

By Xin He Jia · 2026-09-03

Converting a bundt (tube) pan to a round pan, the classic error is treating the outer diameter as the diameter — the chimney eats roughly 15% of the area. A bundt is a ring, not a circle.

The correct math: subtract the chimney

ring area = π(outer r² − chimney r²); equivalent Ø = 2√(ring area ÷ π)

Chimney bore is estimated at 38% of the outer diameter (varies by maker, ±0.1").

Bundt ↔ equal-area round

BundtEqual-area round
6" bundt≈ 5.5" round
8" bundt≈ 7.4" round
9" bundt≈ 8.3" round
10" bundt≈ 9.2" round
12" bundt≈ 11.1" round

Feel it: a 10-inch bundt holds like a 9.2-inch round — one size smaller than intuition.

Matching a loaf pan

A standard 900 g / 2 lb loaf (19.6×10.6×11 cm) holds ~2.3 L at 70% fill. A 9–10" bundt recipe (1.4–1.6 L of batter) fits one loaf loosely — use volume (batter ÷ pan volume), not area, because the loaf is much taller.

What must not leave the bundt

The reverse (round recipe into a bundt) usually works: multiplier from the table, about −10% time (rings conduct faster).

Bake Scaler (by Xin He Jia): the tube pan is one of 11 shapes — the ring area subtracts the chimney automatically, converting to rounds, squares, loaves. Fully offline, one-time purchase — no ads, no subscription.

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Bake Scaler

Scale any recipe to any pan in a second. 11 shapes, multiple pans, whole-egg suggestions, unit guard. One-time purchase, no ads, no subscription, fully offline.

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