Rebar Sizes in Canada: 10M to 55M Size Chart

Canadian rebar comes in eight standard metric sizes: 10M, 15M, 20M, 25M, 30M, 35M, 45M and 55M. The number is the bar's nominal diameter in millimetres, rounded, so a 15M bar is about 16 mm across and weighs 1.570 kg per metre. These sizes are set by CSA G30.18, the Canadian standard for carbon-steel reinforcing bars.

Canadian rebar size chart

These are the nominal values for each bar size. Imperial figures are converted and rounded.

A quick way to remember the pattern: the cross-sectional area of each size is a round number (100, 200, 300, 500 mm² and so on), and the weight follows directly from the area, because steel weighs about 7,850 kg per cubic metre. Area in mm² × 0.00785 gives kg per metre.

How Canadian sizes compare to US rebar

US rebar uses numbered sizes (#3, #4, #5 and up), where the number is the diameter in eighths of an inch. The two systems don't line up one-to-one, which matters when you're reading American details, buying from a US source or following a product spec written for the US market.

"Closest" is not the same as "equivalent". The areas differ, so a substitution changes the amount of steel in the member. If a drawing calls for one system and you can only get the other, the engineer of record needs to approve the swap.

Which sizes get used where

The size and spacing on any job come from the structural drawings, or for houses, from the requirements that apply to your design. As a general picture of what we cut and bend most often:

• 10M: slabs on grade, light walls, ties and stirrups, and general residential work.
• 15M: footings, foundation walls, grade beams and dowels. It is the workhorse size for houses and small commercial buildings.
• 20M and 25M: heavier footings, columns, beams and suspended slabs in commercial and multi-unit buildings.
• 30M and larger: heavily loaded columns, transfer beams, large foundations and civil work such as bridges and retaining structures.

Bigger is not automatically better. Larger bars need longer lap splices and development lengths, more concrete cover and bigger bend diameters, so engineers often prefer more bars of a smaller size where the layout allows it.

Reading the bar itself

Canadian rebar is deformed: the ribs rolled onto the surface lock the bar into the concrete. Each bar also carries rolled-in markings that identify the producing mill, the bar size and the grade. The most common grade on Canadian jobs is 400W, where 400 is the minimum yield strength in megapascals and W means the steel is weldable. Higher-strength 500W bar is also used where the design calls for it.

If you're unsure what you have on site, the markings plus a caliper reading across the bar (ignoring the ribs) will usually settle it.

Working out weight and tonnage

Rebar is often priced and shipped by weight, so it helps to know how to estimate it:

1. Add up the total length of each bar size from your bar list, in metres.
2. Multiply each total by the weight per metre from the chart above.
3. Add the sizes together for the total weight.

For example, 40 bars of 15M at 6 m each is 240 m, and 240 × 1.570 = 376.8 kg. Bent bars are measured along their full developed length, including hooks and bends, which is one reason a proper bar list from a rebar detailer gives a much better number than a rough take-off.

Getting the right bar on site

Most problems with rebar on site come from three things: the wrong size delivered, bars cut or bent to the wrong length, or bundles that don't match the placing drawings. Ordering fabricated rebar from a detailed bar list avoids all three, because every bundle is cut, bent and tagged to a mark on the drawings.

If you have drawings for a project, send them over and we'll put together a bar list and quote. You can also see the rebar products we supply, including straight bar, fabricated dowels and stirrups, and GFRP bar.