Cooking
The scale factor
The single ratio that drives everything else. A recipe for four scaled to six gives 6 / 4 = 1.5.
The Formula
factor = desired servings / original servings
The single ratio that drives everything else. A recipe for four scaled to six gives 6 / 4 = 1.5.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| desired | Servings you want to end up with | servings | The numerator of the division. Six in the worked example. |
| original | Servings the recipe as written makes | servings | The divisor. Four in the worked example. Swapping it with the desired count inverts the factor. |
What Each Symbol Means
desiredservings
Servings you want to end up with
The numerator of the division. Six in the worked example.
originalservings
Servings the recipe as written makes
The divisor. Four in the worked example. Swapping it with the desired count inverts the factor.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to scale a recipe page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Scale A Recipe, filed under Everyday Life. Every number the guide produces comes from substituting into this one line.