🧱 Concrete Calculator

Length (ft)

Width (ft)

Thickness (inches)

Diameter (inches)

Depth / Height (ft)

Number of Columns

Rise per Step (inches)

Run per Step (inches)

Width (ft)

Number of Steps

What is the Concrete Calculator?

This calculator works out how much concrete to order for three common jobs: a slab or square pour, a round column or footing, and a set of steps. Enter the dimensions for your project and it converts them into cubic yards, cubic feet, and the number of 60-lb or 80-lb premixed bags you'd need to buy instead.

How to Use It

Pick the tab that matches your job. For a slab, enter length, width, and thickness in inches. For a column, enter diameter, depth, and how many columns you're pouring. For steps, enter the rise, run, width, and number of steps. Click Calculate to get cubic yards and bag counts.

When to Use It

Use it before ordering ready-mix concrete for a driveway, patio, or slab foundation, before buying bagged concrete for fence post footings or a small column pour, or when estimating material for a set of outdoor steps. A 60-lb bag yields about 0.45 cubic feet and an 80-lb bag about 0.60 cubic feet, and one cubic yard equals 27 cubic feet — it's worth ordering 5–10% extra to cover waste and spillage.

Who Benefits

DIY homeowners planning a weekend concrete pour, contractors estimating material for a bid, and landscapers quoting steps or footings all get a fast, formula-based estimate instead of doing the cubic-foot math by hand.

Frequently Asked Questions

Volume (cubic yards) = Length(ft) × Width(ft) × Thickness(ft) ÷ 27. Add 10% for waste and spillage. Example: a 10×10 ft slab at 4 inches thick = 10 × 10 × 0.333 ÷ 27 = 1.23 cubic yards. Order at least 1.36 cubic yards (10% extra).

For large projects (more than about 1 cubic yard), ready-mix delivered by truck is more economical and ensures consistent quality throughout the pour. For small projects, bagged concrete is more practical — the break-even point is roughly 25–30 bags.

It doesn't add extra automatically — the results are the exact geometric volume for the dimensions you enter. You should still order 5–10% more than the calculated amount to cover spillage, form leakage, and slightly uneven excavation, which is standard practice on any pour.

🧱 Concrete Calculator