Baking Tray Size Calculator

When you switch to a different sized tray, the batter or dough spreads over a different area. This changes the thickness, which affects baking time and texture. Knowing the area ratio lets you adjust the recipe quantity to maintain the same depth.

Measure the inside dimensions at the base, not the top edge or outside. Use the length and width of the flat base where food actually sits. For depth, measure from the inside base to the top of the rim.

Calculate the area ratio between the two trays. If your new tray is 1.5x the area of the original, multiply all ingredients by 1.5 to maintain the same depth. Use our area ratio result for this.

This calculator is for rectangular trays. For round tins, the area is Pi x radius squared. A 20cm round tin has an area of about 314cm², which is similar to a 16x20cm rectangular tray (320cm²).

Common UK baking tray sizes are: quarter sheet (23x33cm), half sheet (33x46cm), and full sheet (46x66cm). Swiss roll tins are typically 23x33cm or 25x38cm. Most home ovens accommodate trays up to about 38x45cm. Always measure the inside dimensions of your tray for accurate calculations.