2.1: Recipe Conversion

Scaling a recipe means that you are adjusting the ingredient quantities for a different amount of servings. While doubling or halving a recipe is relatively easy, you will need to do some math when you want to convert a six-serving recipe for two people or 14 people. Whether you're increasing a recipe or decreasing it—the procedure for adjusting the ingredient quantities is the same.

The first step is to determine a conversion factor. Next, you need to multiply this number by the ingredient measurements.

Determine the Conversion Factor

The conversion factor is a number you are going to use to convert all the quantities. There is a bit of math involved, but it is perfectly fine to use a calculator to do the math calculation. To find your conversion factor, simply divide the desired number of servings (what you want) by the original number of servings (what you have). The resulting number is your conversion factor.

Here is the formula:

\[\dfrac{\text{Desired servings}}{\text{original servings}} = \text{conversion factor} \nonumber\]

For example, to scale a 10-serving recipe down to six portions: Divide 6 (desired servings) by 10 (original servings), 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 in the recipe by this number. In the example above, you would multiply each ingredient amount by 0.6.

Use this simple example to illustrate the calculations. 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

As you see from the example, you are often left with a result that includes a decimal. You are in good luck if it is any of these numbers:

• 0.25: One quarter
• 0.33: One third
• 0.50: One half
• 0.66: Two thirds
• 0.75: Three quarters

When you have other numbers that result, such as the 0.2 of the 1.2 quarters, you can either try to ‘eyeball’ it or you can make a more precise conversion. The eyeballing route works fine for many types of cooking but can produce a flop if you are baking, where exact measurements are more important.

While the rest of the world uses the metric system, those in the U.S. will need to convert 1.2 quarts into ounces. Consulting a cooking conversion chart, you will learn that there are 32 ounces in a quart, so:

32 × 1.2 = 38.4 ounces

You 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. Go back to the cooking conversion tool to find that there are 8 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.

Do not worry this is going to take a long time or a lot of research. Not every ingredient is going to need multiple conversions. Many will be close to the easier decimals and you can use a half-cup, 2/3 cup, or other measures.

When Portion Sizes Change

Suppose that you are working with a book of standardized recipes. These types of recipes will produce a known quantity and quality of food. In addition, suppose you work for a fine catering company and a customer wants you to serve a six-ounce serving of jambalaya for a 284 guests, sit down dinner. Your standardized recipe is for 100, 4 oz. servings. What are you going to do so that you do not run out or produce too much? Convert the recipe by first obtaining the Conversion Factor:

1. Determine the total yield of both amounts:

284 X 6 = 1704
100 X 4 = 400

2. Divide what you want by what you have:

1704 divided by 400 = 4.26, your conversion factor.

3. Every ingredient in the standardized recipe is multiplied by 4.26, and then cook the jambalaya by the recipe directions.