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Measurement systems in Canada and USA

Canadians typically use a mix of metric and imperial measurements in their daily lives.

Canadians typically discuss the weather in degrees Celsius, purchase gasoline in litres, observe speed limits set in kilometres per hour (km/h), and read road signs and maps displaying distances in kilometres. Cars have metric speedometers and odometers, although most speedometers include smaller figures in miles per hour (mph). Fuel efficiency for new vehicles is published by Natural Resources Canada in litres per 100 kilometres, (not kilometres per litre as an analog of miles per gallon) and miles per (imperial) gallon. Window stickers in dealer showrooms often include "miles per gallon" conversions. The railways of Canada such as the Canadian National and Canadian Pacific as well as commuter rail services, continue to measure their trackage in miles and speed limits in miles per hour (although urban railways including subways and light rail have adopted metres and kilometres for distances and kilometres per hour for speed limits). Canadian railcars show weight figures in both imperial and metric. Canadian railways also maintain exclusive use of imperial measurements to describe train length and height in feet and train masses in short tons.

USA used:

Small surfaces are usually measured in square inches, rooms and buildings in square feet, carpet in square yards, property in acres, and territory in square miles.

An act of Congress in 1866 legalized the use of metric units across the U.S. That means imperial-sounding measurements are actually derived from metric units. So at that point, the foot became a fraction of a meter. The math works like this: 36 inches divided by 3 feet is a foot, or 12 inches.

The use of the metric and imperial systems varies according to generations. Newborns are measured in kilograms at hospitals, but the birth weight and length is also announced to family and friends in pounds, ounces, feet and inches. Although Canadian driver's licences give height in centimetres, many Canadians also use feet, inches and pounds to indicate their height and weight. Most kitchen appliances in Canada are labelled with both degrees Celsius and Fahrenheit, and metric cooking measures are widely available; but Fahrenheit is often used for cooking, as are imperial cooking measurements, due to the import of kitchen appliances and recipes from the United States. Canadians also occasionally use Fahrenheit outside of the kitchen, such as when measuring the water temperature in a pool. Stationery and photographic prints are also sold in sizes based on inches and the most popular paper sizes, letter and legal, are sized in imperial units, though many agendas and notebooks are sold in ISO 216 sizes. Canadian football games continue to be played on fields measured in yards (with a gridiron layout with a length of 100.6 metres, or 110 yards, from one goal line to the other); golfers also expect courses to be measured in yards.


Metrication in Canada

Metrication in Canada began in 1970 and ceased in 1985. While Canada has converted to the metric system for many purposes, there is still significant use of non-metric units and standards in many sectors of the Canadian economy and everyday life today. This is mainly due to historical ties with the United Kingdom, the traditional use of the imperial system of measurement in Canada, proximity to the United States, and strong public opposition to metrication during the transition period.

Until the 1970s, Canada traditionally used the imperial measurement system, labelled as "Canadian units of measurement" under Schedule II of the Weights and Measures Act (R.S., 1985, c. W-6). These units have the same names and the same values as United States customary units, with the exception of capacity measures such as the gallon. For example, before metrication in Canada, gasoline was sold by the (imperial) gallon (about 4.55 litres). In cross-border transactions with the United States it was often unclear whether values quoted in gallons were referring to United States gallons (3.79 litres) or imperial gallons.

The Liberal federal government of Pierre Trudeau first began implementing metrication in Canada in 1970 with a government agency dedicated to implementing the project, the Metric Commission, being established in 1971. By the mid-1970s, metric product labelling was introduced. In 1972, the provinces agreed to make all road signs metric by 1977. During the Labour Day weekend in 1977, every speed limit sign in the country was changed from mph to km/h. From the same time every new car sold had to have a speedometer that showed speed in km/h and distance in km. The distances on road signs were changed to kilometres during the next few months. Gasoline pumps changed from imperial gallons to litres in 1979.

There was some resistance to metrication, especially as the sectors of the economy where the federal Weights and Measures Act required metric to be used grew in number. The metrication of gasoline and diesel fuel sales in 1979 prompted 37 Progressive Conservative Members of Parliament to open a "freedom to measure" gas station in Carleton Place, Ontario, selling gas in both imperial gallons and litres. The city of Peterborough, Ontario, was a noted hotbed of opposition to metrication, having been one of the government's three test centres for the metrication process. Bill Domm, a Member of Parliament representing the riding of Peterborough, was one of the country's most outspoken opponents of metrication. During this period, a few government employees lost their jobs for their opposition to metrication. Neil Fraser, an official with Revenue Canada who publicly opposed mandatory metric conversion, was dismissed for "conduct unacceptable for a public servant".


Metrication stalled

Common usage today


Commercial usage

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".

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 historical reason, it is still common to refer to distance in miles. 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. 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.

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.


Canada uses an Avery or imperial bushel (36.369 litres) when selling oats, wheat, and other grains. When dealing with the US oat markets though, special attention must be paid to the definition of bushel weight because US uses a Winchester bushel (35.239 litres). In livestock auction markets, cattle are sold in dollars per hundredweight (short), whereas hogs are sold in dollars per hundred kilograms.

Health care

In the health care system, metric units are often given precedence, although actual metric units may still be different than the United States (for example, for measurements of blood cholesterol, the units are millimole per litre, whereas they are milligram per decilitre in the United States). Most physicians chart patient height and weight in imperial units, and while most growth charts display both systems of measurement, the majority of hospitals officially document such parameters in metric. Dieticians still use kilocalories, and cause most fasteners, machine parts, pumps, piping, and all building materials are sold in imperial or US customary units, many mechanical and civil engineers in Canada mainly use imperial units for these items. Overall building dimensions for new construction are usually in SI units.[citation needed] Many chemical, nuclear and electrical engineers and engineering physicists employ metric units. Unlike in the United States, Canadian engineers are not always educated in both systems but those who are not become keenly aware of the differences between the imperial, metric and US customary systems once they enter the workforce.


Trades associated with machine work, such as machinists, automotive, and heavy duty technicians, frequently use both metric and imperial. Machines made in Canada often incorporate parts from other countries and thus the finished product may have both metric and imperial parts. Farm and industrial equipment manufactured in Canada will most often use inch system fasteners and structural steel, but fluid capacities are always listed in metric.

Building trades such as plumbing and carpentry often use imperial units. Rough timber, drywall, plywood, fasteners, pipes, and tubing are all sold in imperial units. Nails in hardware stores are measured in inches but sold in metric weight packages.

Electricians in every country use metric units such as volts and amperes, but motors and engines in Canada are still often quoted in horsepower. Electric car motors are rated in kilowatts. However, Canada uses, among other things, the US American wire gauge standard instead of the square millimetre (mm2) used in the IEC 60228 standard of the International Electrotechnical Commission. Conduit sizes are in inch diameters, although some manufacturers include the metric size printed on the conduits – for example, 1⁄2 in (13 mm), 5⁄8 in (16 mm), 3⁄4 in (19 mm).


Imperial units remain in common use in firearms and ammunition on the international market. Cartridges may have either commercial or military descriptions. In the former, the manufacturer will choose a name for proprietary reasons, perhaps to associate the name with a brand or designer, or otherwise distinguish it from comparable cartridges. Typical terms include bullet or bore diameter, cartridge length or capacity, a proper name or company. Designs are registered with Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) or Commission internationale permanente pour l'épreuve des armes à feu portatives (CIP) for standardization. Canadian industry follows both conventions, but there is little appetite in the Canadian firearms industry or hobby to pursue metrification simply for the sake of conformity when the trade is global.

Military designations use technical nomenclature to avoid confusion or misrouting of supplies. There are several examples of similar names and similar design dimensions. For example, the civilian cartridge .303 Savage was introduced by the Savage Arms Company in 1894, but is incompatible with the .303 British used throughout the Commonwealth. The .308 Winchester cartridge derived from the 7.62×51mm NATO cartridge in the 1950s, with slight variations in production but not in external dimensions. All four examples are common small arms cartridges in Canada.

Imperial measures are often encountered in the description of cartridges, even when the cartridge is of a relatively recent product introduction (e.g. .204 Ruger, .17 HMR, where the calibre is expressed in decimal fractions of an inch). Ammunition which is classified in metric already is still kept metric (e.g. 9 mm, 7.62 mm). In the manufacture of ammunition, bullet and powder weights are expressed in terms of grains for both metric and imperial cartridges. The popular .30-30 Winchester is a 0.30-inch-calibre (7.62 mm) bullet originally loaded with 30 grains (1.9 g) of smokeless gunpowder.


Canada uses the inch-based paper standard e.g. the US Letter (8.5 inches × 11 inches), rather than the metric-based A4 paper size (210 mm × 297 mm) used throughout most of the world. The government, however, uses a combination of ISO paper sizes, and CAN 2-9.60M "Paper Sizes for Correspondence" specifies P1 through P6 paper sizes, which are the US paper sizes rounded to the nearest 5 mm.

Air transportation

Luggage restrictions and limits at Canadian airports are in metric values with soft imperial conversion values. Runway lengths are given in feet and speed in knots as in the US. Like a number of metric countries altitude is given in feet.

Fuel is nowadays measured in metric units. The Gimli Glider incident in July 1983 is a famous case of a kilogram–pound mistake, in which the miscalculation of the amount of fuel in an Air Canada airplane with a malfunctioning fuel gauge caused the plane to run out of fuel mid-flight.

Education regarding the imperial system

In 2005, the Ontario government announced changes to the secondary school mathematics curriculum that would allow imperial units to be taught along with metric units. This marked a departure from previous governments' efforts to make sure that the curriculum used only the metric system. This was done in light of the refusal or reluctance of much of the private sector to metricate; thus students had been leaving school unprepared for the units used in the workplace. Many other provinces and territories also include the imperial system of measurements as part of their educational curriculum.


The square foot is an imperial unit and U.S. customary unit of area, used mainly in the United States and partially in Canada, the United Kingdom, Bangladesh, India, Nepal, Pakistan, Ghana, Liberia, Malaysia, Myanmar, Singapore and Hong Kong. It is defined as the area of a square with sides of 1 foot.

Although the pluralization is regular in the noun form, when used as an adjective, the singular is preferred. So, an apartment measuring 700 square feet could be described as a 700 square-foot apartment. This corresponds to common linguistic usage of foot.

The square foot unit is commonly used in real estate. Dimensions are generally taken with a laser device, the latest in a long line of tools used to gauge the size of apartments or other spaces. Real estate agents often measure straight corner-to-corner, then deduct non-heated spaces, and add heated spaces whose footprints exceed the end-to-end measurement.

1 Square foot conversion to other units of area:

1 square foot (ft²) = 0.000022956341 acres (ac)

1 square foot (ft²) = 0.000009290304 hectare (ha)

1 square foot (ft²) = 0.09290304 square meters (m²)

1 square foot (ft²) = 144.0000002229 square inches (in²)

1 square foot (ft²) = 0.111111106982 square yards (yd²)

1 square foot (ft²) = 929.0304014422 square centimeters (cm²)

1 square foot (ft²) = 9.290304 square decimeters (dm²)

1 square foot (ft²) = 0.00000009290304 square kilometers (km²)

1 square foot (ft²) = 144003673094580 square microinches (µin²)

1 square foot (ft²) = 92903040000 square micrometers (μm²)

1 square foot (ft²) = 0.0000000358701 square miles (mi²)

1 square foot (ft²) = 92903.04 square millimeters (mm²)


A Guide To House Size

Like most things in the U.S., American houses are big. In 1973, the earliest year for which U.S. Census data is currently available, the average square footage of a house in the U.S. was 1,660 square feet. By 2015, the average square footage of a home increased to a whopping 2,687 square feet, although since then, it’s begun to drop.

In 2019, the most recent year for which data is available, the average square footage of a house dropped to 2,301 square feet. The 1,000+ increase in average square footage comes despite the fact that average household size has dropped from 3.5 to 2.53 people over the same period.

Why Are US Houses So Big?

Larger Houses Are Not That Much More Expensive To Build

From a builder’s point of view, the materials needed to create additional square footage is a small percentage of the overall costs of building a new house. Upping the square footage is an easy and relatively inexpensive way to increase the buyer’s perception of value.

Zoning Laws

Many communities have passed zoning laws specifying that new homes must have a minimum square footage or sit on a certain size of lot. These laws are aimed at preserving the character of a town or neighborhood and limiting the number of homes to be built, as well as who can afford to buy them.

Consumer Demand

We like our walk-in closets, laundry rooms, en suite bathrooms and all the other amenities, and as long as we do, larger homes will continue to be built. However, it appears that millennials and Gen Z’ers are less enamored of size for size’s sake and more concerned with affordability and sustainability, prompting the drop in average square footage from 2015’s high.

Resale Value

Somewhere along the line, Americans stopped thinking of houses as homes and started to think of them as investment opportunities. The thinking went that the larger the home, the greater its resale potential.

Size Vs. Functionality

Many people confuse good design with size, figuring that larger houses will – by virtue of size alone – accommodate them more comfortably. This is a myth. A thoughtfully designed home can maximize its space while a large home can waste tons of space.

National American Standards Institute (ANSI) calculates square footage for detached single-family homes by the sum of finished square footage of each level.

For attached single-family homes, square footage equals the sum of the finished areas on each level, measured to the outside wall or from the centerlines between buildings. They also provide specific guidelines on how to measure finished areas adjacent to unfinished areas, openings to the floor below, above- and below-grade finished areas, garages, and more.

Multiple Service Listings (MLS) also reports on a home’s primary livable, permitted square footage. It does not include garages, other buildings or unpermitted structures on the property.

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