Concrete & Masonry
Concrete Yard Calculator
Enter the area and depth of the pour. The calculator gives the exact volume with waste and the number of cubic yards to order from a ready-mix plant.
Worked example
- 20 x 12 x 4/12 = 80 cu ft.
- 80 / 27 = 2.963 cu yd; plus 5% = 3.111 cu yd.
- Ready-mix is usually ordered in quarter yards, so round up to 3.25 cu yd.
Common sizes at a glance
| Size | Cubic yards to order | Exact volume with waste |
|---|---|---|
| 10 x 10 ft, 4 in | 1.50 | 1.30 cu yd |
| 12 x 20 ft, 4 in | 3.25 | 3.11 cu yd |
| 16 x 40 ft drive, 5 in | 10.50 | 10.37 cu yd |
| 24 x 24 ft, 4 in | 7.50 | 7.47 cu yd |
| 30 x 50 ft, 6 in | 29.25 | 29.17 cu yd |
How ready-mix is ordered
Ready-mix plants sell concrete by the cubic yard, and most take orders in quarter-yard steps. That is why the result shows two numbers: the exact volume and the amount to order.
In the worked example, a 20 x 12 ft pour at 4 in comes to 3.11 cu yd with 5% waste. You cannot order 3.11, so the calculator rounds up to 3.25.
Feet, inches and the 27 rule
A cubic yard is 3 ft x 3 ft x 3 ft, or 27 cu ft. The math is length times width times depth in feet, then divided by 27. Depth is the part people get wrong, because 4 in is a third of a foot, not 0.4.
Enter depth in inches and let the calculator convert it. For a driveway or slab with two depths, run each part and add the yards.
Order a little extra, not a lot
With a truck, coming up short is costly: a second delivery for half a yard can take hours to arrive while the first part sets. A small waste margin of 5 to 10% is common on formed flat work.
Too much extra has its own problem. Leftover concrete has to go somewhere, so have a spare form or a few post holes ready to take what is left.
Before the truck shows up
- Confirm the truck can reach the forms, or plan for a pump or wheelbarrows.
- Check the forms are braced and at the right height.
- Ask your supplier about the minimum load and any short-load fee.
- Have enough helpers and tools ready to place and finish at once.
Turning yards into a budget
Once you know the yards, the concrete per yard price calculator multiplies them by your quoted price and adds labor for your state. For a small job you may still prefer bags, and the concrete calculator shows both side by side.
Questions
How many square feet does a yard of concrete cover?
At 4 in deep, one cubic yard covers about 81 sq ft. At 6 in it covers about 54 sq ft.
Why does the order amount differ from the exact volume?
Suppliers sell in quarter yards, so the calculator rounds your exact volume up to the next quarter.
How many yards for a 24 x 24 slab?
At 4 in deep with 5% waste the exact volume is 7.47 cu yd, so you would order 7.50.
How this works: formulas and typical values are listed on our method page; every data source and its license is on sources.
Last reviewed November 2026.