Concrete Quantity Calculator
How Much Concrete Do I Need?
Estimate concrete quantity for slabs, patios, driveways, pads, footings, walls, piers, stairs, and small flatwork. Calculate cubic yards, bags, ready-mix loads, waste allowance, estimated weight, and basic material cost.
Main unit
Cubic yards
Formula
ft³ ÷ 27
Waste range
5%–10%
Quick formula
Always confirm final order quantities with your contractor or concrete supplier before scheduling delivery.
Concrete yardage calculator
Choose a project type, enter dimensions, add waste, and estimate concrete yards, bags, truckloads, weight, and material cost.
Project note
Use this for flat rectangular pours such as slabs, patios, driveway sections, shed pads, and sidewalks.
Concrete needed
Order amount with waste
1.96 yd³
1.78 yd³ before waste.
Bag yields are approximate. Ready-mix capacity, minimum loads, short-load fees, and delivery rules vary by supplier. Always confirm order quantity before scheduling concrete.
For slabs and flatwork
Use this for patios, shed pads, walkways, garage slabs, driveway sections, and general rectangular concrete pours.
For delivery planning
See approximate ready-mix yards, short-load risk, concrete weight, and basic material cost before contacting suppliers.
For bag comparison
Compare ready-mix yards against 40 lb, 60 lb, and 80 lb bag counts to decide whether bags are practical.
How to calculate concrete
Concrete quantity is usually measured in cubic yards. For a rectangular slab, multiply length by width by thickness to get cubic feet. Then divide by 27 because one cubic yard contains 27 cubic feet.
Example: a 12 ft by 12 ft slab at 4 inches thick is 144 square feet. Four inches equals 0.333 ft, so the slab volume is about 48 cubic feet. Divide 48 by 27 to get about 1.78 cubic yards before waste.
Small projects often need a waste allowance because the subgrade may not be perfectly level, forms may vary, and some material is lost during placement. A 5 to 10 percent allowance is common for many small pours.
How much concrete do common projects need?
How much concrete FAQs
How much concrete should I order?
Order the calculated cubic yards plus a waste allowance. For many small slabs and flatwork projects, 5 to 10 percent extra is common.
How many cubic yards are in a truckload?
Many ready-mix trucks carry around 8 to 10 cubic yards, but capacity and delivery minimums vary by supplier and region.
How much does one cubic yard of concrete weigh?
A common estimating number is about 4,000 to 4,100 pounds per cubic yard for normal-weight concrete.
When should I use a more specific calculator?
Use a slab, footing, wall, stairs, bag, or truckload calculator when the project has a specific shape, delivery constraint, or cost detail.