Conversion Factor

Often you need more or fewer servings than a recipe makes. Multiplying or dividing the amount of ingredients to increase or decrease the yield of a recipe is called scaling.

 
To convert a recipe, first you need to find out the total amount to produce:

Portion Size x Number of Servings Needed = TOTAL TO PRODUCE

The total to produce will be my new yield. In order to scale, you need to use the new yield to find the conversion factor:

Conversion Factor

1. Find your conversion factor: Divide the desired new yield by the original yield:

Yield is the specific amount of product that the recipe makes, may be expressed in volume, weight or servings.

       New Yield
———————— = CONVERSION FACTOR
       Old Yield

2. Then multiply each ingredient in the recipe by the conversion factor to get the new ingredient amount. Note: if your conversion factor is not a whole number, but has a decimal, you can either multiply by the exact conversion factor or round up! For example, round 5.5 up to 6.

Old Quantity x Conversion Factor= NEW INGREDIENT QUANTITY

When calculating a conversion factor, the new and old yields can be in any unit (cups, ounces, pounds, servings, etc) as long as the numerator and the denominator are in the same unit.

The mathematical conversion described above do not take into account changes in spices, equipment and cooking time. Good cooks learn to use their judment, knowledge of cooking principles and skills to compensate for these factors. 

               1. Spices and Seasonings: Spices and seasonings such as garlic and ginger (fresh or dried), salt, dried herbs, and spices should not be scaled at the same level as other ingredients. They are potent so you will need less. Start with small quantities, use common sense and taste frequently. For example, if you are multiplying all ingredients by a factor of 4, multiply spices by 1.5 to begin, and add more if you need to. Remember: you can’t take it out, but you can always add more.

               2. Equipment: When you change the size of a recipe, you must often change the equipment used as well. If you’re doubling the recipe, use a pan that will hold double the volume. Make sure the depth of the food is the same as it was in the original recipe. If a single batch comes about halfway up the side of the pan, a double batch should be the same depth. This ensures even cooking and prevents you from having a mushy, too-thick centre and burnt edges. If you end up with a significantly thicker or thinner layer, try adjusting the cooking time and temperature. For thicker baked goods, back the temperature down about 25°F (10°C) and cook for a little longer. For thinner baked goods, do the opposite: up the temperature and cook for less time. Watch carefully for doneness cues and adjust accordingly.

              3. Cooking Time: You may need to adjust cooking time as you scale up, do not multiply time specifications given in a recipe by the conversion factor used with the recipe’s ingredients.  Cooking time will be affected, however, by changes in evaporation rate or heat conduction caused by changes in pots and pans or bakeware. Larger quantities will often require a slightly longer cooking time. Taste and adjust accordingly.