Trade Math
2 Units of Measurement
Canadian cooks should feel comfortable working in three different measurement systems. Two of these systems (U.S. and imperial) are closely related, while the third (S.I., more commonly called metric) is different from the other two.
Although the metric system was introduced in Canada a number of years ago, the food industry and home cooks still rely heavily on equipment and cookbooks imported from the United States. In addition, because we used imperial measurements in Canada for the sale of liquids, some industry recipes will call for imperial measurements rather than U.S. liquid measurements.
The imperial and U.S. measuring systems evolved out of the system used in Europe prior to the 20th century. Although both the imperial and U.S. systems use the same terminology, there are slight differences in actual measurements that you must account for, particularly with volume.
The easiest way to work with the three systems is to have different sets of measuring devices: one for the metric system, one for the imperial system, and one for the U.S. system. Alternatively, you could have one set of devices that have measurements for all three systems indicated. U.S. measuring instruments can be used with slight adjustments for imperial measuring.
It is not good practice to use two systems of measurement when preparing a recipe. Working between two systems of measurement in a recipe may result in inaccuracies that could affect the final product’s taste, yield, consistency, and appearance. To ensure a consistent and successful result, a good practice is to convert the recipe into one standard system of measurement.
The S.I. (Metric) System: Types, Units, and Symbols
All measuring systems have basic units for length, mass (weight), capacity (volume), and temperature. The basic units for the metric system are shown in Table 1.
| Type of Measurement | Unit | Symbol |
|---|---|---|
| length (distance) | metre | m |
| mass (weight) | gram | g |
| capacity (volume) | litre | L |
| temperature | degrees Celsius | °C |
Note that the abbreviation or symbol of the unit is not followed by a period and that all the abbreviations are lowercase letters except for litre which is usually a capital L.
In the metric system, the basic units are turned into larger or smaller measurements by using a prefix that carries a specific meaning as shown in Table 2. The most commonly used prefixes are kilo (k), centi (c), and milli (m).
| Prefix | Symbol | Meaning |
|---|---|---|
| kilo | k | 1000 |
| hecto | h | 100 |
| deca | da | 10 |
| deci | d | 1/10 or 0.1 |
| centi | c | 1/100 or 0.01 |
| milli | m | 1/1000 or 0.001 |
When you read a measurement in the metric system, it is fairly easy to translate the measurement into a number of the basic units. For example, 5 kg (five kilograms) is the same as 5 × 1000 (the meaning of kilo) grams or 5000 grams. Or 2 mL (two millilitres) is the same as 2 × 0.001 (the meaning of milli) litres or 0.002 litres. This process is discussed further in the section on converting below.
The most commonly used measurements in commercial kitchens are mass (weight), capacity (volume), and temperature.
Units of Length (Distance)
The basic unit of length or distance in the metric system is the metre. The most frequently used units of length used in the Canadian food industry are the centimetre and millimetre. The units of length in the metric system are shown in Table 3.
| Unit | Abbreviation | Length (Distance) |
|---|---|---|
| kilometre | km | 1000 meter |
| hectometre | hm | 100 metres |
| decametre | dam | 10 metres |
| metre | m | 1 metre |
| decimetre | dm | 0.1 metres |
| centimetre | cm | 0.01 metres |
| millimetre | mm | 0.001 metres |
Units of Mass (Weight)
The basic unit of mass or weight in the metric system is the gram. The most frequently used units of mass or weight used in the Canadian food industry are the gram and kilogram. The units of mass in the metric system are shown in Table 4.
| Unit | Abbreviation | Mass (Weight) |
|---|---|---|
| tonne | t | 1000 kilograms |
| kilogram | kg | 1000 grams |
| hectogram | hg | 100 grams |
| decagram | dag | 10 grams |
| gram | g | 1 gram |
| decigram | dg | 0.1 g |
| centigram | cg | 0.01 g |
| milligram | mg | 0.001 |
Units of Capacity (Volume)
The basic unit of volume or capacity is the litre. The most commonly used units in cooking are the litre and the millilitre. The units of volume in the metric system are shown in Table 5.
| Unit | Abbreviation | Volume |
|---|---|---|
| kilolitre | kL | 1000 L |
| hectolitre | hL | 100 L |
| decalitre | daL | 10 L |
| litre | L | 1 L |
| decilitre | dL | 0.1 L |
| centilitre | cL | 0.01 L |
| millilitre | mL | 0.001 L |
Occasionally, you will encounter a unit of volume called cubic measurement (sometimes used to express the volume of solids or the capacity of containers), and the units will be expressed as “cc” or cm3 (cubic centimetre). Cubic centimetres are the same as millilitres. That is, 1 cc = 1 cm3 = 1 mL
In the metric system, 1 mL (cc) of water weighs 1 gram. We will explore this later when discussing the difference between measuring by weight and by volume.
1. Quantity of product or business.
2. A type of measurement that measures the space taken up by a substance.