Cake Pan Conversion Calculator

How it is calculated

The tool compares the floor area of the two pans. For a round pan the one size you enter is the diameter, area = π × (size ÷ 2)²; for a square pan it is the side, area = size × size. The scaling factor is new area ÷ old area, shown to two decimals, and you multiply every ingredient by it. Areas are labelled cm², so enter sizes in centimetres; two pans measured in inches would still give the right factor, but the cm² labels would then be misleading. Only round and square shapes are available, and there is no field for a rectangle's second side. Both sizes are required and each must be above 0 and at most 200 (cm); anything else shows no result. Pan height is not asked for, so the method assumes the batter stays at about the same depth. A factor below 1 means you scale the recipe down, above 1 up.

Common mistakes

• Entering the radius instead of the diameter for a round pan. The size field is the full width across the pan, so a 20 cm pan is 20, not 10.
• Choosing square for a rectangular pan and entering only one side. The tool squares that one number, so a 23 × 33 cm tin entered as 23 gives an area of 529 cm² instead of 759 cm².
• Measuring the outside of the tin. Use the inside size at the batter line, since the rim and wall thickness take up space.
• Rounding the egg count blindly. A factor of 1.68 on 3 eggs gives 5.04; beat one egg and add part of it.
• Expecting the bake time to scale by the same factor. The factor adjusts quantities, but timing usually changes only slightly, so watch the cake instead of the clock.