Yards of Concrete Calculator

One cubic yard of concrete is 27 cubic feet. That fills a 10 × 10 ft slab about 3¼ inches thick, or about 81 sq ft at 4 inches. Pick your shape below, enter the size, and you'll get the cubic yards, the bag count and the cost.

Dimensions

Length

Width

Thickness (inches)

4″ for patios/walkways, 5–6″ for driveways.

Waste, price & bags

Waste / extra (%)

Price per cubic yard

$/yd

Bag size

Cubic yards needed

1.78cu yd

With 10% waste, order 1.96 cu yd.

With waste

1.96 cu yd

Cubic feet

48 cu ft

80-lb bags

Estimated cost

$313

Show the math

cu ft = 144 × (4 ÷ 12) = 48

cubic yards = 48 ÷ 27 = 1.78

+ 10% waste = 1.96 cu yd

bags = ceil(52.8 ÷ 0.60) = 88

How to use this calculator

Pick the shape: slab, wall or footing strip, or round column.
Enter the size in feet and inches. Thickness is in inches.
Leave waste at 10% unless you have a reason to change it.
Add your local price per yard if you have a quote.
Read the cubic yards. Round up when you order.

Formula

slab cu ft = L × W × (thickness ÷ 12)
strip cu ft = L × W × D   (all in feet)
column cu ft = π × (diameter ÷ 2)² × height × quantity
cubic yards = cu ft ÷ 27
bags = ceil(cu ft × (1 + waste%) ÷ yield)   (80 lb = 0.60, 60 lb = 0.45)

Worked example

A 12 × 12 ft patio, 4 inches thick:

cu ft = 144 × (4 ÷ 12) = 48

cubic yards = 48 ÷ 27 = 1.78

+ 10% waste = 1.96 cu yd

Second example

Four 12-inch round columns, 4 ft tall:

cu ft = π × 0.5² × 4 × 4 = 12.57

cubic yards = 12.57 ÷ 27 = 0.47

+ 10% waste = 0.51 cu yd

Yards of concrete calculator diagram of a slab, strip footing and round column

What this calculator doesn't cover

It gives the volume of concrete for slabs, footings and round columns. It doesn't allow for an uneven subgrade, forms that bow, or concrete left in the truck or pump line, so order the extra it suggests. Ask your supplier about minimum orders and short-load fees.

Reference tables

Cubic yards and 80-lb bags for common slabs

Slab size	Cu yd @ 4"	Cu yd @ 6"	80-lb bags @ 4"	80-lb bags @ 6"
10 × 10 ft	1.23	1.85	56	84
12 × 12 ft	1.78	2.67	80	120
16 × 16 ft	3.16	4.74	143	214
20 × 20 ft	4.94	7.41	223	334
24 × 24 ft	7.11	10.67	320	480
30 × 30 ft	11.11	16.67	500	750

Volumes and bags exclude waste; add about 10% when you order. An 80-lb bag yields about 0.60 cu ft.

Tips & buying advice

Always round your order up. Running out of concrete halfway through a pour leaves a cold joint, and that's a weak spot.
Ready-mix plants usually sell in quarter- or half-yard steps, so round up to the next step.
Small orders often carry a short-load fee. If you need under about 1 cubic yard, bags can make more sense.
Measure thickness in a few spots. If your base dips an inch, a big slab can eat a lot more concrete than you planned.

Frequently asked questions

How many yards of concrete do I need for a 10x10 slab?

About 1.23 cubic yards at 4 inches thick, or 1.36 with 10% extra. At 6 inches thick it's about 1.85 cubic yards.

How much is a yard of concrete?

In 2026 a cubic yard of ready-mix usually costs around $145–$195 delivered, depending on your area and the mix strength. Small loads cost more per yard because of short-load fees, so get a local quote.

How many square feet does a yard of concrete cover?

It depends on thickness. One yard covers about 81 sq ft at 4 inches, 65 sq ft at 5 inches and 54 sq ft at 6 inches. Divide 324 by the thickness in inches.

How do I calculate yards of concrete?

Multiply length × width × thickness, all in feet, to get cubic feet. Then divide by 27. A 12 × 12 slab at 4 inches is 12 × 12 × 0.333 = 48 cubic feet, which is 1.78 yards.

How many 80-lb bags make a yard of concrete?

About 45. Each 80-lb bag makes about 0.60 cubic feet, and a yard is 27 cubic feet.

Should I order extra concrete?

Yes, about 10%. Uneven ground, form bulges and spills all use more than the math says. Being short is a much bigger problem than having a little left over.

What is the minimum amount of concrete I can order?

Many plants deliver as little as 1 cubic yard, but loads under about 3–4 yards often carry a short-load fee. Ask about it when you call.

Built and maintained by Sikander Mushtaq. Formulas checked against Quikrete 80-lb concrete mix yield, 2026 ready-mix cost guide. See our methodology and sources, or learn about YardageMath. See our editorial policy.

Last updated: October 10, 2026

Estimates only. Confirm quantities with your supplier or contractor. Read the full disclaimer.