Ready-mix is sold by the cubic yard. Enter your sizes in feet and inches, and the ticket gives you the number to call in, with your waste allowance already added.

Square feet per cubic yard

One cubic yard is 27 cubic feet, so it covers 324 ÷ thickness (in inches) square feet.

Thickness	Area one yard covers	Yards per 100 ft²
3 in	108.0 ft²	0.93
4 in	81.0 ft²	1.23
5 in	64.8 ft²	1.54
6 in	54.0 ft²	1.85
8 in	40.5 ft²	2.47

Cubic yards to bags

If the job is small enough for bags, here is what each amount works out to.

Cubic yards	80 lb bags	60 lb bags
0.5	23	30
1	45	60
1.5	68	90
2	90	120
3	135	180

Before you call the supplier

Give them the total from the ticket, which already includes your waste allowance.
Ask about their minimum load and any short-load fee for small orders.
Check the truck can reach the pour, or ask about a pump or wheelbarrow access.
Have the forms set and the base compacted before the truck arrives.

Cubic yards = length (ft) × width (ft) × thickness (in ÷ 12) ÷ 27

Worked example: a driveway order

A single driveway 12 ft wide, 40 ft long and 5 in thick is 7.41 cubic yards exactly. With 10% extra the order is 8.15 yards. If your supplier sells in quarter yards, that rounds up to 8.25 yards; ask how they sell part loads before you order.

Partial loads and minimum orders

A full ready-mix truck carries about 8–10 cubic yards. Orders below that often carry a short-load fee, about $60–$110 on average (Lawn Love, October 2026). Two ways to keep it down:

Pour connected parts (slab, footings, steps) on the same day so they go on one truck. Add them as parts and the ticket gives one total.
For very small jobs, compare the fee with the cost of bags: the ticket shows both.

Measuring mistakes that cost yards

Measuring the outside of the forms. Measure inside the forms, where the concrete goes.
Assuming the ground is flat. Check thickness in several places; low spots take extra concrete. Use the deepest typical reading, or raise the waste allowance.
Forgetting thickened edges, steps or footings. Add each one as its own part.
Form boards are smaller than their names. A 2×4 form board is 3½ in tall and a 2×6 is 5½ in. Enter the thickness you'll actually pour.

Cubic yards to cubic metres

Cubic yards	Cubic metres
1	0.76
2	1.53
3	2.29
5	3.82
8	6.12
10	7.65

Questions

How many yards of concrete for a 10 × 10 slab?

At 4 inches thick: 1.23 cubic yards exactly, or 1.36 yards with 10% extra.

How many yards for a 20 × 20 slab?

At 4 inches thick, 5.43 cubic yards with 10% extra. At 6 inches, 8.15 yards.

How much area does one yard of concrete cover?

Divide 324 by the thickness in inches: 81 square feet at 4 inches, 54 square feet at 6 inches. The table above lists the common thicknesses.

How much does a cubic yard of concrete weigh?

About 4,000 lb. Normal-weight concrete is roughly 145–150 lb per cubic foot, and a cubic yard is 27 cubic feet.

Should I round up when ordering ready-mix?

Yes. Order the total with your waste allowance, and ask the supplier how they sell partial yards and what their minimum load is. Running short mid-pour is far more costly than a little left over.

Can I order yards for several parts at once?

Yes. Add the slab, footings, post holes and steps as separate parts. The ticket shows each part and one total to give the supplier.

Guides: Bagged concrete vs ready-mix · How to measure for concrete

Sources

Bag yields: QUIKRETE Concrete Mix No. 1101 data sheet. Conversions: 1 cubic yard = 27 cubic feet = 0.7646 cubic metres.

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