Scaling means to measure out the ingredients of a recipe for the quantity you need. You can scale a recipe by doubling or halving the ingredients to adjust for the number of servings you will need. In Baking, if the recipe calls for a 9 inch round pan and all you have is a 10 inch round pan what do you do? You can convert the recipe to fit the size pan you want to use.
To do this, you need to calculate what is referred to as the ‘conversion factor’. The conversion factor is usually calculated by taking the desired volume and dividing it by the original volume (desired volume/original volume).
Here is an easy example:
If you wish to double a recipe’s ingredients, the conversion factor would be 2. Let’s say that the original recipe makes 2 cups of batter. The desired volume is 4 cups of batter (doubled). The conversion factor is desired volume/original volume = 4 cups/2 cups = 2. Therefore, you would multiply each ingredient amount in the recipe by 2 to double the recipe.
To go from a 9 inch round pan to a 10 inch round pan both 2 inches high, the conversion factor is calculated using the volume of each pan. Since the size of a round cake pan is determined by its diameter, and the radius is needed for the calculation, divide the diameter by 2 to get the radius.
Volume (10 inch round pan) = πx 52 x 2 = x (25) x 2 =50π
Volume (9 inch round pan) = πx 4.52 x 2 = x (20.25) x 2 = 40.5π.
So, the conversion factor would be: Desired/Original = 50π/40.5π= 1.25 approximately.
So, if your original recipe calls for 2 cups of flour, converting that to a 10 inch round pan, you would now take 2 cups flour times the conversion factor of 1.25 for a total of 2 ½ cups flour. Do this for the remaining ingredients in the recipe.
To go from a 9 inch round cake pan that is 2 inches high to a 9x13x2 inch rectangular pan:
First calculate the volume of the rectangular pan:
Volume= length x width x height = 13 x 9 x 2 = 234
Volume of the 9 inch round pan (see example 2) is 40.5π. Since the value of π is approximately 3.14, 40.5 π = 40.5 x 3.14 = 127.
So, the conversion factor would be: Desired/Original = 234 / 127 = 1.8 approximately or, rounding up, 2.
Now multiply each ingredient of the recipe by 2 to get your original recipe to fit the new larger, rectangular pan.