About test weight for Canadian grains

The following information answers questions about test weight and how grain volumes are measured and describes how grain is measured for test weight in Canada.

What is test weight?

Test weight is the measure of grain density determined by weighing a known volume of grain. In Canada's grain grading specifications, it is expressed in grams per 0.5 litre or kilograms per hectolitre. Test weight is a grading factor for many grains under the Canada Grain Act. Despite the name, test weight is not a measure of weight or quantity, but is a measure of density (a measure of mass in a given volume).

In the current Canadian grading system, test weight is assessed after dockage is removed and is expressed as kilograms per hectolitre, kg/hL (kilograms per 100 litres of volume), or as g/0.5L (grams per half-litre). This is the official measure in Canada, and the Official Grain Grading Guide issued by the Canadian Grain Commission specifies minimum test weights required to make grades for certain grains.

In Canada, producers commonly refer to grain weight using Imperial (British) measurement. However, the Canadian Grain Commission uses metric measurements, which can then be converted to Avery and Winchester bushels. Both Avery and Winchester bushels differ from the Imperial bushel.

The importance of test weight

A bushel of wheat in Canada may not be equal to a bushel of wheat in the United States. The Winchester bushel volume is smaller than the British bushel volume that is used to calculate the Avery bushel used in Canada.

In addition to the difference in volume, there is a difference in how the effect of grain compaction is treated. In Canada, determining test weight takes compaction into account, and conversion of the official metric test weight measure to pounds per bushel is based on the Imperial bushel, and is referred to as pounds per bushel-Avery. Conversion of the official metric test weight measure to pounds per bushel based on the Winchester bushel does not take compaction into account, and is referred to as pounds per bushel-Winchester. Therefore, it is critical to make sure which type of bushel is being used when making formal grain transactions.

If you are selling your grain by contract to a company in the United States, test weights specified in the contract are in pounds per bushel. Usually, this means the Winchester bushel. However, if you get a test weight measurement for your grain at a primary elevator in Canada, it will be in Avery bushels. The difference between the two bushels could mean a loss for you.

Example: If the contract for Select CW two-row barley specifies a test weight of 45.5 lb/bu, this means that it is 45.5 pounds per Winchester bushel (45.0 lb/W bu). The equivalent test weight in the test weight conversion chart for barley is 48.8 pounds per Avery bushell (lb/A bu). Therefore, any shipment of barley with a Canadian test weight of less than 48.8 lb/A bu will not meet the United States contract specifications.

Conversely, the Canadian test weight of 45.5 A lb/ bu is equivalent to 42.4 lb/W bu. so will not meet a specification for 45.5 lb/ W bu.

Imperial, Avery and Winchester bushels

The Imperial bushel is 36.369 litres (or 1.2843 ft³). It is the British bushel and is commonly used by Canadian producers. In the table below, the figures showing conversion to Imperial are approximate values.

The Avery bushel is the Imperial bushel, but the weight conversion accounts for grain compaction. It is in use in Canada.

The Winchester bushel is 35.239 litres (or 1.244 ft³) and is in use in the United States.

The following table shows how these measurements differ in reference to test weights of specific grains and grades.

Measurement in:	g/0.5 L	kg/hL	lb/Imperial bushel (approx.)	lb/Avery bushel	lb/Winchester bushel
Special Select Canada Western two-row barley	303	63.0	49.1	50.5	47.0
Special Select Canada Western six-row barley	298	62.0	48.3	49.7	46.2
No. 1 Canada Western Red Spring wheat	365	75.0	58.2	60.1	56.6
No. 1 Canada Western Amber Durum wheat	387	79.0	61.5	63.3	60.1

Converting to Winchester bushels

Conversions from grams per half litre to pounds per Winchester bushel involve a straight mathematical conversion. The conversion doesn't account for grain compaction because the weight per small volume is simply multiplied to reach the larger volume. The same conversions are used for each crop.

Example: This range of conversions is the same in all the tables.

Sample range of conversions

g/0.5 L	lb/W bu
291	45.2
292	45.3
293	45.5
294	45.6
295	45.8

Conversion factors and different grains

Different grains have different densities. As a result, all different grains have different conversion factors. When converting from grams per half litre to pounds per Avery bushel, there is no single conversion factor that can be applied to all grains.

Make sure to use the conversion factors and methods appropriate for the grain being measured.

Contacts

For more information please contact the Statistics unit