<P> In restaurants, wine is usually served by the litre, 750 mL (26 - imperial - fluid - ounce; 25 - US - fluid - ounce) or 500 mL (18 - imperial - fluid - ounce; 17 - US - fluid - ounce) bottle, but a wine glass is measured in ounces . Similarly, fast food restaurants (e.g. McDonald's Quarter Pounder) often advertise measurements of food and drink in US customary units, but converted to metric units, because either the containers are made to US standards, or the franchise is US - based and uses a standard size for its products . Thus in Canada a 20 US fluid ounce bottled soft drink is labelled as 591 mL (or occasionally rounded up to 600 mL). Beer in bottles continues to be 12 imperial fluid ounces (labelled as 341 mL), but beer in cans is filled to 12 US fluid ounces (labelled as 355 mL). There is also a larger sized beer bottle which is labelled as containing 1.18 L (42 imperial fluid ounces; 40 US fluid ounces). Some of these package sizes have been introduced since Canadian metrication began; for example, the traditional Canadian soft drink can was 10 imperial fluid ounces (284 mL), later marketed as 280 mL . Only in the early 1990s did the US - derived 355 mL size displace it . Television sets and computer screens are also measured in inches . Standard and special fasteners like alloys, nuts, bolts, washers, studs, tapping, self drilling screw and socket screware are often quoted in both imperial and metric; products range from ⁄ in (0.91 mm) diameter up to 4 in (100 mm). </P> <P> Supermarkets will often advertise foods such as meats and produce "per pound", and small businesses are exempt from having metric scales and legally sell by the pound . While most supermarket scales display both metric and imperial units, products advertised by the pound in a supermarket flyer are invariably sold to the customer (at the point of sale) based on a price "per 100 grams" or "per kilogram". </P> <P> Construction materials, including construction lumber and drywall, continue to be sold in imperial measurements; retrofitting metric - sized (designed for 400 mm centres) wallboard on old 16 in (410 mm) spaced studs is difficult . In English - speaking Canada commercial and residential spaces are mostly (but not exclusively) constructed using imperial units and advertised accordingly, while in French - speaking Quebec commercial and residential spaces are constructed in metres and advertised using both metric and imperial units as equivalents . However, the zoning by - laws and building codes that govern construction are in metric, although most building codes will also contain imperial equivalents . In addition, rural areas in Western Canada (Canadian Prairies) were mapped and segmented using the Dominion Land Survey . This based most rural roads on a mile measurement which when viewed from the air has the appearance of a checkerboard or grid . Because of this standard now etched into the landscape, it is still common to refer to distance in miles, since counting the number of mile roads is easy . In contrast, in much of southern Ontario the basic survey grid was based on a mile - and - a-quarter (1.25 mi), which corresponds almost exactly to a 2 kilometre grid and which makes miles no more natural than kilometres . It should be noted that 1.25 mi is equal to 100 chains (or 10 furlongs) and it was that sized grid that was used in the original surveys and thus would have been more familiar . </P> <P> Free trade with the United States has resulted in continued exposure to the US system . Since the United States is Canada's largest trading partner and vice versa, Canadian exporters and importers must be accustomed to dealing in US customary units as well as metric . </P>

When did canada go to the metric system