Converting Weight Measurements to Volume Measurements
Some products are purchased by weight and then expressed and measured in recipes as volume measurements such as teaspoons,
tablespoons, cups and quarts. To calculate accurate costs for these products in the menu costing process, the relationship of each product's
weight-to-volume relationship needs to be determined.
For example, sugar is usually purchased by the pound, a weight measurement. But sugar is usually measured in volume units like
tablespoons or cups in recipes. So to have accurate cost data in the recipes, there needs to be a way to convert the cost of a pound of sugar
into a volume unit like a tablespoon or cup.
The first step in doing this is to weigh a volume unit, say a cup, of sugar. You can see on the table below that a cup of sugar weighs 7.1
ounces. If we purchase sugar by the 50-pound sack, which costs $24, we can calculate the cost per ounce of sugar as 3 cents ($24 divided by
[50-pound container times 16 ounces per pound]). The cost of sugar per cup is 7.1 ounces times 3 cents or 21.3 cents.
Each product's density or weight per a given unit of volume can be different, so each product needs to be weighted at least once. Here are
weights, in ounces, of some common kitchen ingredients:
Yield Testing by Example
A meat example. When I was in the barbecue business, beef brisket represented a large portion of our total food cost. Since fluctuations in
shrinkage and trim could have a major effect on our costs, we would conduct yield tests of our brisket at least monthly and sometimes even
weekly if we were having food cost issues. Here's an illustration of how we conducted our yield tests.
Yield Test - Beef Brisket
Piece
Raw
Weight (lbs)
Cooked
Trim
Usable
Yield %
1
9.5
6.3
1.2
5.0
53.0%
2
11.2
7.2
1.5
5.7
51.0%
3
10.6
6.9
1.7
5.2
49.0%
4
8.7
5.4
1.0
4.4
50.0%
5
Average
9.8
6.5
1.4
5.1
52.0%
10.0
6.4
1.4
5.1
51.0%
Here we've taken five pieces of brisket and weighed each piece before cooking, after cooking, the weight of the trim and the amount of
brisket that's available to use. We'd do this with four to six pieces, all from different boxes and take an average. Usually the yield was about
50 percent but sometimes this would get as low as 45 percent, which had a very negative effect on our food cost. In these cases we would
double-check our cooking procedures and contact our supplier. Yields usually improved with the next brisket delivery.
This exercise is also important because it shows that the cost per pound or ounce of a product may increase significantly due to preparation
and cooking steps. With brisket, a customer's 8-ounce serving actually costs as much as a full pound of brisket coming in the backdoor.
A produce example. Likewise, if your kitchen preps the produce it uses, some of the usable product will be lost during the preparation
process. A simple yield test is needed to see how much usable product remains.
For example, say a restaurant uses tomato slices on burgers and sandwiches. It purchases tomatoes by the case and a case contains about
90 tomatoes. Yield tests show you get about eight to 10, say nine slices per tomato. The yield would then be about 810 (90 x 9) slices per
case if every tomato was in usable condition or it was possible to have a 100 percent yield. If there were usually three or four bad or spoiled
tomatoes per case then the yield would be say 96 percent (86.5/90) or 777 (810 X 96 percent) usable slices.
Now, this level of detail may seem like overkill, but if shortcuts are taken throughout the process on many products, the cumulative effect,
when calculating ideal food cost in particular, can be significant. It's best to get into the details, even minutiae of each product so you'll have
better information and more reliable results when this data is applied and used.