Cubic metres, bags, rebar, and cost for slabs, footings, columns, and stairs. Reviewed by a licensed Canadian P.Eng.
Estimator · v3.2 · CA
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Order this much— m³
Litres— L
Cubic yards— cu yd
30 kg bags—
25 kg bags—
Rebar 15M @ 300— m
Cost—
— How the calculator works
From dimensions to a ready-mix order.
Volume is length × width × thickness, returned in cubic metres. Round columns use π × radius² × height. Stairs are figured riser-by-riser as a stack of rectangles — the method that matches what gets poured for cast-in-place steps.
A waste allowance of 5% to 10% is added to the raw volume. Eight percent suits most residential pours in Canada — driveways, garage pads, basement floors. Push it to ten for hand-dug footings or rough excavation. Ready-mix is delivered in 0.25 m³ increments, so the figure rounds up to the next quarter cubic metre.
Bag yields use the printed values on Canadian pre-mixed concrete: a 25 kg bag gives about 0.0125 m³, a 30 kg bag about 0.015 m³ (Sika, Quikrete Canada, King Packaged Materials). The rebar estimate assumes 15M bar at 300 mm centres each way — common for a basement slab or driveway to CSA A23.1.
— Concrete mix selection
Strength and exposure under CSA A23.1.
In Canada, concrete is specified by compressive strength in MPa (megapascals) at 28 days, plus an exposure class that drives air entrainment, water-cement ratio, and minimum cement content. The exposure classes you'll see on a delivery ticket come from CSA A23.1:24.
Canadian concrete strength and exposure classes (CSA A23.1)
Strength
Exposure Class
Typical Use
Air %
20 MPa
N (Normal)
Basement floors, mass fill
None
25 MPa
F-2
Interior slabs, footings
4–7%
30 MPa
F-1, C-2
Garage floors, foundations
5–8%
32 MPa
C-2
Residential driveways, exposed slabs
5–8%
35 MPa
C-1
Structural slabs with de-icing salt exposure
5–8%
40+ MPa
A-1, S-1
Bridges, parking structures, industrial
5–8%
Exposure classes are the part that matters most across Canada. C-class covers chloride exposure (de-icing salts, marine). F-class covers freeze-thaw with low chloride. N means no exposure to chlorides or freezing. If your driveway will see road salt, specify C-2 minimum — N or F-class won't last.
— Slab thickness & foundation depth
Sizing for Canadian conditions.
Slab thickness is set by load. Foundation depth is set by frost, which varies more across Canada than almost anywhere else in the world. Both are governed by the National Building Code of Canada and provincial amendments.
100mmSidewalks, patios. 25 MPa with air entrainment. 152×152 mm welded mesh.
125mmDriveways for cars. 32 MPa, C-2 exposure. 15M rebar @ 400 mm.
150mmGarage floors, RV pads. 32 MPa, C-2. 15M @ 300 mm each way.
200mmCommercial and agricultural. Engineered reinforcement schedule required.
Frost depth varies sharply by region: roughly 1.2 m in southern Ontario and the Lower Mainland, 1.5–1.8 m across the Prairies and Quebec, and up to 2.4 m in northern communities. Footings must extend below the local frost line or be designed as a frost-protected shallow foundation. Check your municipal building department before excavating — frost-heave damage is not covered by any concrete specification.
— Cold-weather concreting
Pouring through a Canadian winter.
Cold-weather concreting is part of normal practice in Canada, but it requires planning. CSA A23.1 defines cold-weather conditions as any time the mean daily temperature is below 5°C or expected to drop below 5°C within 24 hours of placement. The objective is to keep the concrete above 10°C until it reaches at least 5 MPa — usually a few days under heated conditions.
Heated water and aggregates to raise the batch temperature to 10–20°C
Type HE (high-early-strength) cement or an accelerator admixture
Insulated tarps, blankets, or hoarding with propane heaters
Continuous temperature monitoring for the first 72 hours
No placement on frozen subgrade — thaw it with ground heaters first
Concrete that freezes before reaching 5 MPa loses long-term strength permanently. In Edmonton, Winnipeg, or Quebec City through January, expect ready-mix suppliers to charge a winter premium and require insulated forms.
For workability, Canadian concrete is specified by slump in millimetres (per CSA A23.2-5C). Most residential flatwork lands at 80–100 mm. Higher slump pours easier but loses strength if added water is the cause — request a superplasticizer instead. For air-entrained mixes in C and F exposure classes, air content runs 4–8% — your supplier verifies this at the truck.
MT
Reviewed by Marc Tremblay, P.EngLicensed professional engineer (Ontario & Quebec) · 13 years across residential, commercial, and cold-climate concrete. Calculator logic and content checked against CSA A23.1:24, CSA A23.3:19, and the National Building Code of Canada 2020. Last reviewed May 2026.
— Common questions
Quick answers.
How many bags of concrete in a cubic metre?
About 80 bags at 25 kg, or 67 bags at 30 kg. A 30 kg bag of pre-mixed concrete yields roughly 0.015 m³. Above 0.5 m³, ready-mix delivery is cheaper than bags.
How much concrete for a 3 × 3 m slab?
0.90 m³ at 100 mm thick. With 8% waste, order 1.0 m³ — ready-mix trucks deliver in 0.25 m³ increments.
What concrete strength is required for a Canadian driveway?
32 MPa with 5–8% air entrainment, CSA A23.1 exposure class C-2. This handles de-icing salts and freeze-thaw cycling. In milder coastal areas without salt exposure, F-1 is acceptable.
How deep should footings be?
Below the local frost line — typically 1.2 m in southern Ontario, 1.5–1.8 m across the Prairies and Quebec, up to 2.4 m in northern communities. Check your municipal building department.
Bags or ready-mix delivery?
Under 0.5 m³, mixing 30 kg bags yourself is cheaper. Above that, ready-mix wins on price and labour. Most plants charge a small-load fee under 3 m³.
Do I need a building permit?
Yes, for any structural concrete in Canada — foundations, retaining walls over 1 m, suspended slabs. Garden patios and walks usually don't need one, but rules vary by municipality. Check before pouring.