Let's say you have a recipe that serves six people, but you want to make it for two people instead. Or even trickier, what if a recipe serves four people, but you need to make it for six? Or 14? It doesn't matter whether you're increasing a recipe or decreasing it—the procedure for adjusting the ingredient quantities for a different number of portions is the same. We call this scaling a recipe.
The first step is to determine a conversion factor; next, you need to multiply this number by the ingredient measurements.
If this number is an odd amount for that particular measurement, you will then need to convert to a different type of measurement. This may sound like a lot of work, but you won't need to convert every ingredient in a recipe into another form of measurement. And with these formulas, you are sure to have your recipe turn out perfectly.
Determine the Conversion Factor
The first thing you need to do is calculate your conversion factor, which is a number you're going to use to convert all the quantities. There's a tiny bit of math involved, but it's OK to use a calculator!
To find your conversion factor, simply divide the desired number of servings by the original number of servings. The resulting number is your conversion factor. Here's the formula:
———————— = conversion factor
For example, to scale a 10-serving recipe down to six portions you divide 6 by 10, which gives you a conversion factor of 0.6.
Applying the Conversion Factor
Once you determine the conversion factor, you need to multiply each ingredient measurement by this number. In the example above, you would multiply each ingredient amount by 0.6.
Let's work through a simple example to illustrate how this works. Say your recipe calls for 2 quarts of chicken stock.
All you need to do is multiply 2 quarts by your conversion factor of 0.6:
2 quarts × 0.6 = 1.2 quarts chicken stock
Converting the Measurements to Make Sense
Great! But wait for a second...What exactly are 1.2 quarts? Well, questions like that are why most of the world uses the metric system. The rest of us are going to have to convert 1.2 quarts into ounces. If we consult a handy cooking conversion chart, we will learn that there are 32 ounces in a quart, so:
32 × 1.2 = 38.4 ounces
We can round that down to about 38 ounces, but that's still kind of a weird amount. It would be more clear if it were given in cups, wouldn't it? Our cooking conversion tool reminds us that there are eight ounces in a cup, so:
38 ÷ 8 = 4.75
Which means 1.2 quarts is equal to approximately 4 3/4 cups, a much more doable number.
Not every ingredient is going to need multiple conversions, so don't worry this is going to take a long time or a lot of research.