Concrete & construction
Concrete Patio Calculator
Works a patio pour, where the finish and the joints matter more than the thickness.
Result
Concrete is ordered by the cubic yard and delivered in fixed increments, so the figure you order is always rounded up. Most crews add 5% to 10% for spillage, uneven subgrade and over-excavation; running short mid-pour is far more expensive than a little waste. Excavation, base preparation, forming, reinforcement and control joints are not included.
Get a Free Business AuditHow the calculation works
Area times thickness in cubic yards, plus subbase and any reinforcement. A patio carries foot traffic rather than vehicles, so the thickness requirement is modest, and the things that determine whether it is satisfactory are the finish, the drainage fall and the control joints.
What moves the number
- Area and a thickness appropriate to foot traffic.
- Finish chosen and the labour it requires.
- Drainage fall away from the building.
- Control joint spacing.
Where this one goes wrong
Fall away from the building is the detail that cannot be corrected later, because a patio draining toward a wall puts water against it permanently, and the amount of fall needed is modest and easily lost in a sloppy screed. Set it deliberately. Finish is the other thing to decide before pouring rather than during, since broomed, stamped and exposed aggregate finishes need different timing and different crew numbers on the day.
Before you quote
- Set a fall away from the building and check it before pouring.
- Decide the finish before the pour, not during it.
- Plan control joints relative to the slab thickness.
Questions
About this calculator
How much fall does a patio need?
A modest amount away from the building, and it is easily lost in a sloppy screed. A patio draining toward a wall puts water against it permanently, and that detail cannot be corrected after the concrete has set.
Does the finish need deciding in advance?
Yes, because broomed, stamped and exposed aggregate finishes need different timing and different crew numbers on the day. Deciding during the pour means working out the logistics while the concrete sets, which never goes well.
How thick does a patio need to be?
Modest, since it carries foot traffic rather than vehicles, with the local requirement governing. The thickness is rarely what makes a patio fail; drainage, subbase and joint layout are, and all three are decided before pouring.
The formula
cubic yards = area x thickness/12 / 27, plus waste
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How to use this calculator
- Length (ft) (ft). Enter your own figure; the page starts at 16 ft.
- Width (ft) (ft). Enter your own figure; the page starts at 12 ft.
- Thickness (in) (in). Enter your own figure; the page starts at 4 in.
- Waste allowance (%). Enter your own figure; the page starts at 8%.
- Concrete per cubic yard ($). Enter your own figure; the page starts at $165.
- Labour per sq ft ($). Enter your own figure; the page starts at $5.
The result updates as you type, so you can try a figure, see what it does to cubic yards to order, and change it back. Nothing you enter is sent anywhere or saved.
A worked example
These are the figures the calculator opens with. Every number in the results column below is produced by the same calculation the page runs, so you can follow it through before putting your own figures in.
What goes in
| Input | Value |
|---|---|
| Length (ft) | 16 ft |
| Width (ft) | 12 ft |
| Thickness (in) | 4 in |
| Waste allowance | 8% |
| Concrete per cubic yard | $165 |
| Labour per sq ft | $5 |
What comes out
| Result | Value |
|---|---|
| Cubic yards to order main result | 2.8 |
| Patio area | 192.0 |
| Concrete cost | $453.75 |
| Estimated total | $1,414 |
| Cost per square foot | $7.36 |
That is 2.8 cubic yards over 192.0 square feet, about $1,414 all in, or $7.36 a square foot.
How sensitive the answer is
Holding everything else steady and changing only concrete per cubic yard, this is what happens to cubic yards to order. It is worth knowing which of your inputs the answer actually hinges on, and which barely move it.
| Concrete per cubic yard ($) | Cubic yards to order |
|---|---|
| $83 | 2.8 |
| $124 | 2.8 |
| $165 example above | 2.8 |
| $248 | 2.8 |
| $330 | 2.8 |
Every other input is held at the example value while this one changes, which is not how a real job behaves. Treat it as a guide to which number matters most, not as five separate quotes.
What each figure means
- Length (ft) (ft)
- Measured in ft, starting at 16 ft.
- Width (ft) (ft)
- Measured in ft, starting at 12 ft.
- Thickness (in) (in)
- Measured in in, between 0 and 120, starting at 4 in.
- Waste allowance (%)
- A percentage, between 0 and 40, starting at 8%.
- Concrete per cubic yard ($)
- A money amount, starting at $165.
- Labour per sq ft ($)
- A money amount, starting at $5.
What the results tell you
| Result | What it is |
|---|---|
| Cubic yards to order | The headline result. A decimal figure. |
| Patio area | A decimal figure. |
| Concrete cost | A money figure. |
| Estimated total | A money figure. |
| Cost per square foot | A money figure. |
Order slightly more than this
Volume calculations assume a level, properly prepared base and exact dimensions. Sub-base variation, over-excavation and spillage all consume concrete, which is why most contractors add a margin. Running short mid-pour is far more expensive than a small overage.
Keep going
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