How much concrete do you need? Enter your dimensions and get an instant estimate in cubic metres and cubic yards — plus gravel, footings, post holes, and rebar.
Estimate only. For pours over ~1 m³, ready-mix delivery is usually cheaper and easier than bags. Always confirm with your supplier.
Estimate only. Weight uses ~1.5 t/m³ for crushed gravel — pick a material to update it.
Estimate for filling round holes (Sonotube / post footings). Add extra if you're setting posts that displace concrete.
For round pads, hot-tub bases, and circular patios. Estimate only — confirm with your supplier.
For continuous strip footings and grade beams. Enter the total combined length of all footing runs.
A two-way grid at the spacing you choose (e.g. 16″ o.c.). Total linear rebar estimate — add for laps and overlaps when ordering.
Concrete is ordered by volume, in cubic metres (m³) — the unit ready-mix is actually sold in. To estimate it yourself, multiply length by width by thickness using the same units, then convert. The calculator above does this instantly, but here's the math behind it.
Worked example: a 20 ft × 20 ft slab poured 4 inches (0.33 ft) thick is 20 × 20 × 0.33 ≈ 133 ft³. Multiply by 0.0283 and that's about 3.8 cubic metres.
Always add about 10% to your number for spillage, uneven sub-grade, and slight over-excavation. Running short part-way through a pour is far more expensive than ordering a little extra, because concrete sets on a clock and a second delivery means a second minimum charge.
Most slabs sit on a compacted gravel base — use the Gravel / Base tab to estimate volume and tonnage. For reinforcement, the Rebar Spacing tab estimates how much steel a two-way grid needs at your chosen spacing.
Different materials weigh very different amounts for the same volume — which matters when you're ordering by the tonne, or working out how heavy the spoil is when hauling away dirt, clay, or broken-out concrete. The gravel calculator uses about 1.5 t/m³ for crushed gravel. To estimate weight for another material, multiply its volume in cubic metres by the density below.
| Material | Approx. density | Per cubic yard |
|---|---|---|
| 3/4″ crushed gravel / road base | 1.5 t/m³ | ~1.15 t |
| Drain rock / pit run | 1.6 t/m³ | ~1.22 t |
| Sand | 1.6 t/m³ | ~1.22 t |
| Topsoil / dirt (dry) | 1.2 t/m³ | ~0.92 t |
| Clay (dry) | 1.4 t/m³ | ~1.07 t |
| Broken concrete (rubble) | 1.4 t/m³ | ~1.07 t |
| Solid concrete (cured) | 2.4 t/m³ | ~1.83 t |
Approximate dry bulk densities — moisture and compaction can change these by 20% or more. Wet clay or saturated topsoil weighs noticeably more, and broken concrete varies with how tightly it's piled. Confirm with your supplier or disposal site for exact figures.
For small jobs, bagged concrete looks cheaper but rarely is once you add the mixer, hauling, labour, and weaker results. For most structural pours, a ready-mix truck is stronger and better value. We break the full cost comparison down on our main site's FAQ.
Got your number? We can pour it for you — driveways, patios, slabs, and more across Greater Victoria. Get a free quote →
Multiply length × width × thickness in the same units. In feet: length × width × thickness (in feet) = cubic feet; multiply by 0.0283 for cubic metres. A 20 × 20 ft slab at 4″ is about 133 ft³ ≈ 3.8 m³. Add ~10% for waste — or just use the calculator above.
A 30 kg bag yields roughly 0.5 ft³, so a cubic metre takes about 71 bags. Over ~1 m³, ready-mix is usually cheaper and stronger.
The minimum ready-mix order is 1 cubic metre (concrete in Canada is ordered by the m³). But any order under 5 m³ carries a short-load fee on top of the concrete price, and it varies by plant. That's why small pours cost more per metre — it's just part of small-job pricing. Get a quote →
A residential driveway is typically 4 inches; 5–6 inches for heavier vehicles like trucks or RVs.
About 10% over your calculated volume, to cover spillage, uneven sub-grade, and over-excavation. Ordering a little extra is far cheaper than coming up short mid-pour.
Cured, solid concrete weighs roughly 150 lbs per cubic foot — about 2,400 kg (2.4 tonnes) per cubic metre. To picture it: a full wheelbarrow of mixed concrete holds about half a cubic foot and weighs 75–100 lbs, so it's a real workout. And about 0.4 cubic metres of broken-out concrete — a typical small slab demo — runs around 2,000 lbs, right at the safe payload limit of a half-ton pickup like an F-150. That's why even a "small" tear-out fills a truck fast and is heavier than people expect.
A calculator gets you close. We'll come out, measure, and give you a free written fixed-price quote for your concrete or excavation project anywhere in Greater Victoria.