How to Scale a recipe #cooking


Have you ever had one of those moments when you try a recipe and it is just so good you have to make it for your friends. Then you realize it’s written for the wrong number of people. It’s written for 4 but you have 11 that you want to have at the dinner party.

What do you do?

That is when you scale the recipe. No, it’s not as bad as scaling a mountain. Though it might sound like it at first if you don’t like math. It’s not really that bad though.

Honestly there is some math involved but stick with me, we will get through it.

So let’s work with this recipe I have for Mongolian Beef:

Servings: 4

2 pounds flank steak
1/2 cup cornstarch
3/8 cup oil
1 teaspoon ginger, grated
2 tablespoons garlic, sliced
1 cup water
1 cup soy sauce
1 cup brown sugar
1 teaspoon red pepper flakes
6 large green onion, sliced into thirds

The first thing we need to do is come up with our conversion factor. Sounds ominous doesn’t it? It’s not. All it is, is the number we need to multiply by to scale our recipe. As you can see the recipe is written for 4 and we have 11 coming to the party. So all we have to do is divide 11 by 4 and we get a conversion factor of 2.75. Now if we were only to have 2 at our party we would still do the same 2 divided by 4. That would give us a conversion factor of 0.5.

Given that we will have 11 all we need to do is take our nifty little conversion factor of 2.75 and multiply each of our ingredient amounts by that factor. So instead of just 2 pounds of flank steak we would need 5.5 pounds.

You may notice that we have some fractional amounts in our list of ingredients, e.g. 1/2 cup cornstarch. Those you do have to convert to decimal format first. That is easy enough. Just divide the top number by the bottom number in the fraction. In this case divide 1 by 2 and you get 0.5. We then multiply our decimal value by our conversion factor of 2.75 and we get 1.375. (we will get back to that in  a moment)

After we do that for each of the ingredients we end up with the following:

Servings: 11

5.5 pounds flank steak
1.375 cup cornstarch
1.03 cup oil
2.75 teaspoon ginger, grated
5.5 tablespoons garlic, sliced
2.75 cup water
2.75 cup soy sauce
2.75 cup brown sugar
2.75 teaspoon red pepper flakes
16.5 large green onion, sliced into thirds

Now we need to make this a little more useful. For example what is 1.375 cups of cornstarch really? Obviously there is 1 whole cup and an additional .375 cups. How do we make that useful? There are a couple of ways. Using the guidelines found at mathisfun.com  we can easily convert .375 to 3/8 of a cup. We can do the same for most of the other values too.

One though isn’t so easy. The oil. We know we will need 1 cup of oil. But how much oil is .03 cups. Honestly for this recipe you don’t need it. But for the sake of the example we’ll go with it. So, if we look at our handy dandy conversion chart we will find that there are 8 ounces in a cup. If we multiply .03 by 8 to find out how many ounces we need. We find we have about a 1/4 ounce as the result (.24 to be exact). Our chart shows us that a 1/2 ounce is equal to 1 tablespoon. So 1/4 ounce would be 1/2 tablespoon.

In the end our final scaled recipe looks like this:

5.5 pounds flank steak
1  3/8 cup cornstarch
1 cup + 1/2 tablespoon oil
2 3/4 teaspoon ginger, grated
5 1/2 tablespoons garlic, sliced
2 3/4 cup water
2 3/4 cup soy sauce
2 3/4 cup brown sugar
2 3/4 teaspoon red pepper flakes
17 large green onion, sliced into thirds (we just round this up for ease)

It is a little daunting but with some practice it isn’t too bad. Just think our parents and grandparents did this in their head. I bet you never knew they were such geniuses did you?

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