How do I convert a round cake recipe to a square pan?

A round pan holds less batter than a square pan of the same stated size. A 20cm round is roughly equivalent to an 18cm square. Use this calculator to get the exact volume ratio and batter multiplier.

How full should I fill a cake pan?

Fill cake pans to about two-thirds (67%) full. This allows room for the cake to rise without overflowing. For sponge cakes that rise a lot, fill to 60%. For dense cakes like fruitcake, you can fill to 75%.

Does bake time change with pan size?

Yes. Deeper pans take longer to bake because heat needs to reach the centre. As a guide, add about 5 minutes per extra centimetre of depth. Wider, shallower pans bake faster. Always check with a skewer.

How do I calculate bundt pan volume?

A bundt pan has a hollow centre tube. Its volume is the outer cylinder minus the inner cylinder. The inner tube is typically about 40% of the outer diameter. A standard 25cm bundt holds about 2.5 litres.

BakeCalcs

Baking Pan Conversion Calculator

Convert recipes between different pan shapes and sizes. Calculate batter adjustments and bake time changes.

Original Pan

Shape

Select the shape that matches your area

Diameter

Depth

Thickness or depth of the material

Target Pan

Shape

Select the shape that matches your area

Length

Depth

Thickness or depth of the material

How We Calculate This

This calculator compares the volume of two baking pans and gives you a multiplier to adjust your recipe. It accounts for different shapes, sizes, and depths.

Volume formulas

Round: π × r² × depth
Square: side × side × depth
Rectangle: length × width × depth
Bundt: π × (R² - r²) × depth (inner tube ~40% of diameter)

The batter multiplier is the target volume divided by the original volume. If the multiplier is 1.5, use 1.5× the original recipe quantities.

Frequently Asked Questions

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Last updated: March 2026

All calculations are based on standard ratios and conversions. Results may vary with specific ingredients, equipment, and conditions.