Free Cake Pan Conversion calculator with clear step-by-step results.
A round pan and a square pan hold the same batter when their base areas match, and the side of that equivalent square is simply the square root of the circle's area. If your square pan is a different size, the area ratio is the factor to scale the recipe by.
Round pan area
Area = pi x (diameter / 2)^2
Equivalent square side
Side = square root of the round pan area
No. The square holds about 27% more batter, because a 20 cm circle is 314 cm2 and a 20 cm square is 400 cm2. The matching square for a 20 cm round is about 17.7 cm.
Slightly - square corners receive heat from two sides and set sooner, so check for doneness a few minutes early and consider lining the corners.