In a dream world, recipes would all follow the same format and be written especially for you. It would make precisely how much you needed to make, list ingredients in the amount you happen to have in your fridge, and, of course, work just right every time.

But in the real world, recipes are written by different people all over the world. Some are intended to feed a banquet of 300, while others call for the teeniest 1/8th of a teaspoon of vanilla extract. Some might call for 2 1/2 cups of flour when you only have 2—but you still really want to make those cookies (and really don’t want to go to the grocery store!).

Fortunately for all of us, there’s an easy answer to solve some of those issues. We call it the Recipe Conversion Factor (RCF).

One of the first things students learn at the CIA, the RCF’s handiness cannot be overstated. The recipe conversion factor is a simple math equation that helps you to scale recipes for different yields, different ingredient quantities, and to some extent, different pan sizes.

Here’s an example: our recipe for Chimichurri Sauce yields 1 cup. We are cooking another dish that calls for 1 1/2 cups of chimichurri, so we need to scale the chimichurri recipe (increase the yield) to make 1 1/2 cups, rather than the 1 cup it makes as written.

Using the following formula, we can determine the RCF to solve this dilemma:

recipe conversion factor: Desired yield over original yield equals recipe conversion factor

Easily remembered as New Over Old, we divide the new (desired) yield of 1.5 cups with the old yield of 1 cup: 1.5 divided by 1 = 1.5. The Recipe Conversion Factor is 1.5. Now, we can multiply each ingredient by our RCF to determine their new quantity, to achieve a yield of 1 1/2 cups of chimichurri.

  • 1 cup roughly chopped flat-leaf parsley leaves (about 1 bunch) x 1.5 = 1.5 cups

  • 1 cup roughly chopped cilantro leaves (about 1 bunch) x 1.5 = 1.5 cups

  • 1/2 cup extra-virgin olive oil x 1.5 = .75 cups

  • 1/4 cup red wine vinegar x 1.5 = .375 cups (which we can round to 1/3 cup)

  • 1 teaspoon kosher salt x 1.5 = 1.5 teaspoons

  • 1/4 teaspoon freshly cracked black pepper x 1.5 = .375 tsp (1/3 tsp)

  • 1/8 teaspoon crushed red pepper flakes x 1.5 = .1875 tsp (which we can round to just shy of 1/4 tsp)

  • 2 large garlic cloves, coarsely chopped x 1.5 = 3 cloves

We can also use this formula to scale other ingredients to a specific quantity of one ingredient. We might do this to finish up a nearly-empty bag of sugar or to account for ingredients we may be short on. This may not be something you find yourself doing often, but once you know the RCF, you might be surprised how often you do!

Here’s an example: you are making Peanut Butter Banana Bread Muffins. The recipe calls for 3/4 cup of mashed banana, from about 2 bananas. When you mash your bananas, you’re a little short—yours only comes to about 1/2 cup. Instead of scrapping the project or running to the store, you decide you want to go forward with the banana you have.

If we follow the same equation of New Over Old, we can determine the RCF.

.5 cup banana / .75 cup banana = .666667 RCF, which we can round to .67. We then multiply the original ingredients by the RCF to determine the new quantities.

  • 1 1/2 cups all-purpose flour x .67 = 1 cup

  • 3/4 teaspoon baking soda x .67 = .5 teaspoon

  • 1 teaspoon baking powder x .67 = .67 tsp (which can be rounded to 2/3 or a heaping 1/2 teaspoon)

  • 3/4 teaspoon ground cardamom x .67 = .5 teaspoon

  • 1/2 teaspoon ground cinnamon x .67 = .33 teaspoon (which can be thought of as a heaping 1/4 teaspoon)

  • 3/4 teaspoon kosher salt x .67 = .5 teaspoon

  • 3/4 cup mashed banana (from about 2 very ripe bananas) x .67 = .5 cups

  • 3/4 cup crunchy or smooth peanut butter x .67 = 5 cups

  • 1/4 cup vegetable oil x .67 = .17 cup (which you can measure as a scant 1/4 cup, or break down into 2.75 tablespoons)

  • 3/4 cup light or dark brown sugar x .67 = .5 cup

  • 2 eggs x .67 = 1.34 eggs (we’ll explain that below)

  • 1/2 teaspoon vanilla extract x .67 = .33 teaspoon (which can be thought of as a heaping 1/4 teaspoon)

Some notes about certain ingredients:

  • Eggs are frequently called for by “the each,” meaning 1 egg, 2 egg, etc. When you use the RCF for eggs, you will often have a result that is a fraction of an egg. The best way to handle this is to crack on egg and weigh it on the scale. If that egg is, say, 1.5 oz, and your original recipe called for 2 eggs, you’ll want to find the total weight of the 2 eggs (1.5 oz x 2 = 3 oz), and then multiply that number by the RCF: 3 oz x .67 = 2.01 oz. 2 oz is your new quantity. Read more about that here. 

  • Leavening ingredients, like baking soda, baking powder, and yeast, do not always scale perfectly. Use the RCF as a guide, but use your judgement. If the new quantity is barely a pinch, you are usually safe using about 1/4 tsp to make sure there is enough. If it is several tablespoons, remember that leaveners have a flavor in too large of quantities, so feel free to scale down if the amount seems large compared to other baking you’ve done. It’s not a perfect system, so trust your gut.

Changing the ingredients quantities will, of course, impact your yield. Because you are a kitchen freestyler, this won’t stress you out. Fill your muffins tins to the same level you would normally (this recipe says 3/4 way full), and you will simply make less muffins.

If you are making recipes in a cake pan or something similar, you can either use the same size for a smaller result (be sure to check your item sooner, as less batter means a shorter cooking time), or you can apply the RCP to your cake pan.

If a recipe calls for a 9-inch cake pan, multiply that by your RCF (we’ll use the muffin batter as an example, so RCF is .67).

9 inch x .67 = 6.03 inches, so you would select a 6-inch cake pan. This is not always perfectly accurate, since pan sizes are somewhat dependent on the makeup of the batter, so you’ll want to use your judgement. If the pan seems too full, bake the remaining batter in a small tin or cupcake pan. If it seems very light, use a smaller pan or settle for a flatter cake.

CIA FOODIES

Culinary Math: Recipe Conversion Factor

In a dream world, recipes would all follow the same format and be written especially for you. It would make precisely how much you needed to make, list ingredients in the amount you happen to have in your fridge, and, of course, work just right every time. But in the real world, recipes are written by different people all over the world. Some are intended to feed a banquet of 300, while others call for the teeniest 1/8th of a teaspoon of vanilla extract. Some might call for 2 1/2 cups of flour when you only have 2—but you still really want to make those cookies (and really don’t want to go to the grocery store!). Fortunately for all of us, there’s an easy answer to solve some of those issues. We call it the Recipe Conversion Factor (RCF). One of the first things students learn at the CIA, the RCF’s handiness cannot be overstated. The recipe conversion factor is a simple math equation that helps you to scale recipes for different yields, different ingredient quantities, and to some extent, different pan sizes. Here’s an example: our recipe for Chimichurri Sauce yields 1 cup. We are cooking another dish that calls for 1 1/2 cups of chimichurri, so we need to scale the chimichurri recipe (increase the yield) to make 1 1/2 cups, rather than the 1 cup it makes as written. Using the following formula, we can determine the RCF to solve this dilemma: recipe conversion factor: Desired yield over original yield equals recipe conversion factor Easily remembered as New Over Old, we divide the new (desired) yield of 1.5 cups with the old yield of 1 cup: 1.5 divided by 1 = 1.5. The Recipe Conversion Factor is 1.5. Now, we can multiply each ingredient by our RCF to determine their new quantity, to achieve a yield of 1 1/2 cups of chimichurri.
  • 1 cup roughly chopped flat-leaf parsley leaves (about 1 bunch) x 1.5 = 1.5 cups
  • 1 cup roughly chopped cilantro leaves (about 1 bunch) x 1.5 = 1.5 cups
  • 1/2 cup extra-virgin olive oil x 1.5 = .75 cups
  • 1/4 cup red wine vinegar x 1.5 = .375 cups (which we can round to 1/3 cup)
  • 1 teaspoon kosher salt x 1.5 = 1.5 teaspoons
  • 1/4 teaspoon freshly cracked black pepper x 1.5 = .375 tsp (1/3 tsp)
  • 1/8 teaspoon crushed red pepper flakes x 1.5 = .1875 tsp (which we can round to just shy of 1/4 tsp)
  • 2 large garlic cloves, coarsely chopped x 1.5 = 3 cloves
We can also use this formula to scale other ingredients to a specific quantity of one ingredient. We might do this to finish up a nearly-empty bag of sugar or to account for ingredients we may be short on. This may not be something you find yourself doing often, but once you know the RCF, you might be surprised how often you do! Here’s an example: you are making Peanut Butter Banana Bread Muffins. The recipe calls for 3/4 cup of mashed banana, from about 2 bananas. When you mash your bananas, you’re a little short—yours only comes to about 1/2 cup. Instead of scrapping the project or running to the store, you decide you want to go forward with the banana you have. If we follow the same equation of New Over Old, we can determine the RCF. .5 cup banana / .75 cup banana = .666667 RCF, which we can round to .67. We then multiply the original ingredients by the RCF to determine the new quantities.
  • 1 1/2 cups all-purpose flour x .67 = 1 cup
  • 3/4 teaspoon baking soda x .67 = .5 teaspoon
  • 1 teaspoon baking powder x .67 = .67 tsp (which can be rounded to 2/3 or a heaping 1/2 teaspoon)
  • 3/4 teaspoon ground cardamom x .67 = .5 teaspoon
  • 1/2 teaspoon ground cinnamon x .67 = .33 teaspoon (which can be thought of as a heaping 1/4 teaspoon)
  • 3/4 teaspoon kosher salt x .67 = .5 teaspoon
  • 3/4 cup mashed banana (from about 2 very ripe bananas) x .67 = .5 cups
  • 3/4 cup crunchy or smooth peanut butter x .67 = 5 cups
  • 1/4 cup vegetable oil x .67 = .17 cup (which you can measure as a scant 1/4 cup, or break down into 2.75 tablespoons)
  • 3/4 cup light or dark brown sugar x .67 = .5 cup
  • 2 eggs x .67 = 1.34 eggs (we’ll explain that below)
  • 1/2 teaspoon vanilla extract x .67 = .33 teaspoon (which can be thought of as a heaping 1/4 teaspoon)
Some notes about certain ingredients:
  • Eggs are frequently called for by “the each,” meaning 1 egg, 2 egg, etc. When you use the RCF for eggs, you will often have a result that is a fraction of an egg. The best way to handle this is to crack on egg and weigh it on the scale. If that egg is, say, 1.5 oz, and your original recipe called for 2 eggs, you’ll want to find the total weight of the 2 eggs (1.5 oz x 2 = 3 oz), and then multiply that number by the RCF: 3 oz x .67 = 2.01 oz. 2 oz is your new quantity. Read more about that here. 
  • Leavening ingredients, like baking soda, baking powder, and yeast, do not always scale perfectly. Use the RCF as a guide, but use your judgement. If the new quantity is barely a pinch, you are usually safe using about 1/4 tsp to make sure there is enough. If it is several tablespoons, remember that leaveners have a flavor in too large of quantities, so feel free to scale down if the amount seems large compared to other baking you’ve done. It’s not a perfect system, so trust your gut.
Changing the ingredients quantities will, of course, impact your yield. Because you are a kitchen freestyler, this won’t stress you out. Fill your muffins tins to the same level you would normally (this recipe says 3/4 way full), and you will simply make less muffins. If you are making recipes in a cake pan or something similar, you can either use the same size for a smaller result (be sure to check your item sooner, as less batter means a shorter cooking time), or you can apply the RCP to your cake pan. If a recipe calls for a 9-inch cake pan, multiply that by your RCF (we’ll use the muffin batter as an example, so RCF is .67). 9 inch x .67 = 6.03 inches, so you would select a 6-inch cake pan. This is not always perfectly accurate, since pan sizes are somewhat dependent on the makeup of the batter, so you’ll want to use your judgement. If the pan seems too full, bake the remaining batter in a small tin or cupcake pan. If it seems very light, use a smaller pan or settle for a flatter cake.

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