Concrete Calculator
Find how many 30 kg bags, cubic yards or cubic metres of concrete you need, and what it will cost.
Measure your project
Your answer
That is 36.7 cubic feet, or 1.04 m³. We added 10% extra.
If you buy bags
One 30 kg bag makes 0.014 m³, or 0.5 cubic foot, say Sakrete and Quikrete. These are rounded, so feet and metres can give one bag apart.
If you order a truck (ready-mix)
Ask for 1.25 m³ (about 1.63 cubic yards). We round up to the next 0.25 m³.
This answer is a guide. For footings, driveways or anything that holds weight, check your local building rules or ask a builder or engineer.
Which costs less?
But you must mix 74 bags by hand. That is 2.2 tonnes to lift.
Canadian middle prices from October 2026, before GST/HST. Ask your store or plant for their price.
Quick answers
- A 10 ft square pad, 4 in thick
- 1.36 cubic yards (1.04 m³) with 10% extra. That is 74 bags of 30 kg.
- Bags in a cubic yard
- 54 bags of 30 kg. Each bag makes 0.5 cubic foot.
- Bags in 1 m³
- 72 bags of 30 kg. Each bag makes 0.014 m³.
- How thick?
- 100 mm (4 in) for a car driveway. At least 125 mm (5 in) for trucks or RVs.
How to work it out
- Measure the pad in feet, or switch the calculator to metres.
- Change the thickness from inches to feet: divide by 12.
- Multiply the three sizes together to get cubic feet.
- Add 10% for spills. Divide by 27 for cubic yards, or multiply by 0.0283 for m³.
- For 30 kg bags, divide the cubic feet by 0.5, what one bag makes. Round up.
10 × 10 × 0.333 = 33.3 cubic feet
33.3 + 10% = 36.7 cubic feet
36.7 ÷ 27 = 1.36 cubic yards, or 1.04 m³
36.7 ÷ 0.5 = 73.3 → 74 bags
30 kg bags for common slabs
Each pad here is 4 in thick, the RMCAO figure for a car driveway. We added 10% and counted bags from the size in feet.
| Slab | Cubic yards | m³ | 30 kg bags |
|---|---|---|---|
| 4 × 4 ft | 0.22 | 0.17 | 12 |
| 6 × 6 ft | 0.49 | 0.37 | 27 |
| 8 × 8 ft | 0.87 | 0.66 | 47 |
| 10 × 10 ft | 1.36 | 1.04 | 74 |
| 10 × 12 ft | 1.63 | 1.25 | 88 |
| 12 × 12 ft | 1.96 | 1.50 | 106 |
| 12 × 20 ft | 3.26 | 2.49 | 176 |
| 20 × 20 ft | 5.43 | 4.15 | 294 |
Why feet and metres can differ by a bag
The makers round what a bag makes. They say 0.5 cubic foot, or 0.014 m³. But 0.5 cubic foot is really about 0.0142 m³.
So 1 m³ takes 72 bags if you count in metres. Count in feet, and it takes 71. A 10 × 10 ft slab takes 74 bags in feet, or 75 in metres. Neither is wrong.
A 25 kg bag of Quikrete Fast-Setting makes 0.41 cubic foot. You need 66 of those for a cubic yard.
What a ready-mix truck costs
Plants sell ready-mix by the cubic metre, before GST/HST. Our middle price is $255.50 per m³ for 25 MPa. That is about $195 a cubic yard.
It is the middle of 4 price lists from only 3 companies, so treat it as a rough guide. They are all in Ontario or Calgary, so your area may differ.
Small-load fees
Dufferin and CBM, both in Ontario, add a fee for each small load. Their bands are below. Omega in Calgary mixes on site and charges no such fee.
| Load | Dufferin fee | CBM fee | Total | Per m³ |
|---|---|---|---|---|
| 1 m³ | $400 | $400 | $667 | $667 |
| 2 m³ | $400 | $300 | $933 | $467 |
| 3 m³ | $400 | $300 | $1,200 | $400 |
| 4 m³ | $250 | $175 | $1,316 | $329 |
| 5 m³ | $150 | $0 | $1,483 | $297 |
| 6 m³ | $0 | $0 | $1,599 | $267 |
Total and per m³ use our middle price, Dufferin's fee and about $11 per m³ of plant fees.
- Winter: from 1 Nov to 30 Apr, both add $22 per m³. The calculator can add it for you.
- Plant fees: Dufferin and CBM each add about $11 per m³. Dufferin also adds a fuel charge that changes each month. The calculator includes the $11.
- Smallest load: Dufferin's list says all mixes need a 3 m³ minimum. Yet it lists fees from 1 m³. Ask the plant what it will bring.
- Calgary: Omega says other plants charge $40–$60 per cubic yard on loads under 5 yards. Its own trucks mix on site, with no such fee.
- Price rises: Dufferin's list says prices may rise each 1 January.
Bags or a truck?
The small-load fee is what makes bags win on small jobs. Our bag price is $6.90 for 30 kg, before tax. It is the middle of only 3 stores ($6.20 on sale to $9), so it is a rough guide.
At our middle prices, a truck costs less from about 1.9 m³ (2.5 cubic yards). With the winter fee, it is about 2 m³.
If your plant makes you pay for its 3 m³ minimum, bags win up to about 2.5 m³ instead.
At the first size, you would need about 136 bags. That is 4.1 tonnes of bags to carry, then mix.
How thick, and how strong?
- Floor slab on the ground: at least 75 mm (about 3 in), says the Ontario Building Code.
- Car driveway: 100 mm (4 in), says RMCAO, Ontario's ready-mix group.
- Larger trucks or RVs: at least 125 mm (5 in), says Concrete Manitoba.
Strength is given in MPa. For driveways, garage floors and patios, RMCAO asks for 32 MPa with 5–8% air. Indoor slabs can use 20 MPa.
Our middle price is for 25 MPa. On 2 Toronto-area lists, 32 MPa costs $28–$29 more per m³.
These are general rules. For a driveway or anything that holds weight, check your local building rules. Or ask a builder or engineer.
Questions people ask
How much concrete do I need?
Multiply the length, width and thickness, all in feet. Add 10% extra, then divide by 27 for cubic yards. The calculator above does it in feet or metres.
How many 30 kg bags of concrete are in a yard?
54 bags. Each 30 kg bag makes 0.5 cubic foot, and a cubic yard is 27 cubic feet.
How many cubic feet are in a bag of concrete?
A 30 kg bag makes 0.5 cubic foot, say Sakrete and Quikrete. That is 0.014 m³.
How much is a bag of concrete in Canada?
About $6.90 for 30 kg, before tax. That is the middle of only 3 stores, so check your own.
How much is a yard of concrete in Canada?
Plants sell it by the cubic metre. Our middle price is $255.50 per m³ for 25 MPa, before tax. That is about $195 a cubic yard, plus any small-load fee.
How many yards of concrete are in a truck?
Dufferin's 2026 list prices waiting time per 9 m³ load. That is about 11.8 cubic yards. Ask your plant what its trucks hold.
When does a ready-mix truck beat 30 kg bags?
At our middle prices, from about 1.9 m³ (2.5 cubic yards). Below that, the small-load fee makes bags the cheaper choice.
How thick should a concrete driveway be?
100 mm (4 in) for cars, says RMCAO. At least 125 mm (5 in) for larger trucks or RVs, says Concrete Manitoba.
Where our numbers come from
- Bag size: Sakrete Canada Concrete Mix (30 kg makes 0.014 m³, or ½ cubic foot)
- Bag size: Quikrete Ready-to-Use 30 kg (½ cubic foot, 14 L)
- Fast-Setting mix: Quikrete data sheet (bag sizes and fence posts)
- Bag price: 3 Canadian stores, 30 kg (Oct 2026; few prices)
- Ready-mix price: the middle of 4 price lists from 3 companies (25 MPa, Oct 2026, before tax)
- Small-load and winter fees: Dufferin Concrete 2026 price list (Ontario)
- Small-load fees: CBM Toronto-area price list
- Calgary prices: Omega Ready Mix 2026 price guide
- Driveways and strength: RMCAO residential concrete guide
- Heavy driveways: Concrete Manitoba (at least 125 mm)
- Floor slabs: Ontario Building Code 9.16.4.3 (at least 75 mm)
- Extra for spills: Sakrete slab calculator (10%)
Made by BuildersCount. Last checked 3 Oct 2026.
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