Why does tray area matter for baking?

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.

How do I measure a baking tray?

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.

How do I convert between tray sizes?

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.

What about round versus rectangular trays?

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).

What are standard baking tray sizes in the UK?

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.

BakeCalcs

Baking Tray Size Calculator

Calculate the area and volume of baking trays and compare between sizes.

Tray 1

Length

Width

Depth (optional)

Compare with a second tray

How We Calculate This

This calculator uses simple geometry to work out the area and volume of rectangular baking trays. When comparing two trays, it calculates the ratio so you know how to scale your recipe.

The Formulas

Area = Length x Width (cm²)
Volume = Length x Width x Depth (cm³)
Volume in litres = Volume / 1000
Area ratio = Tray 2 area / Tray 1 area

Common UK Baking Tray Sizes

Standard baking sheet: 38 x 25 cm
Swiss roll tin: 33 x 23 cm
Small roasting tin: 25 x 18 cm
Large roasting tin: 39 x 28 cm
Brownie tin: 20 x 20 cm or 23 x 23 cm

Frequently Asked Questions

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Last updated: February 2026

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