Concrete Calculator
Calculate cubic yards of ready-mix concrete for any slab, footing, or pour from length, width, and depth, plus material cost at your price per yard.
How this calculator works
Every concrete pour — a slab, patio, footing, or pad — starts from the same three numbers: length, width, and depth. This calculator multiplies those together to find cubic feet, then divides by 27 to convert to cubic yards, the unit ready-mix suppliers actually price and deliver by.
Formula: Cubic yards = (Length ft × Width ft × Depth ft) ÷ 27.
Worked example
A 10 ft × 10 ft pour at a 4-inch depth:
- Depth in feet: 4 ÷ 12 = 0.3333 ft
- Cubic yards: (10 × 10 × 0.3333) ÷ 27 ≈ 1.23 yd³
- At $150/yd³, that’s $185.19 before waste.
Cost reference
| Pour size | Depth | Cubic yards | Cost at $150/yd³ |
|---|---|---|---|
| 5 ft × 5 ft | 4 in | 0.31 yd³ | $46.30 |
| 10 ft × 10 ft | 4 in | 1.23 yd³ | $185.19 |
| 20 ft × 20 ft | 4 in | 4.94 yd³ | $740.74 |
How to measure your pour
Measure the finished footprint’s length and width in feet, and use the actual poured thickness — not the excavation depth, which often includes a gravel base beneath the concrete. If your project isn’t a simple rectangle, or has a specific shape like a round column or a narrow curb, use one of the shape-specific concrete calculators below, which apply the correct formula for that geometry automatically instead of forcing it into a length-times-width estimate.
Frequently asked questions
How much concrete do I need for my project?
Multiply length by width by depth (all in feet), then divide by 27 to get cubic yards — that's the number this calculator returns from your three measurements. The hard part is usually getting an accurate depth, since concrete depth is often specified in inches (4 in for a slab, 12 in or more for a footing) and needs converting to feet first.
Should I use this generic calculator or a project-specific one?
This calculator handles any rectangular pour with a single length, width, and depth, which covers most slabs, pads, and footings. If your project has a specific shape — a round column or sonotube form, a curb with a small cross-section, a countertop, or a post hole — a shape-specific calculator applies the right formula automatically instead of asking you to approximate it as a rectangle.
How many cubic yards is a standard ready-mix truck load?
Most ready-mix trucks carry 9-10 cubic yards fully loaded, though trucks can deliver partial loads for a short-load fee, commonly applied under about 3-4 cubic yards. If your calculated volume is small, ask your supplier about their minimum order and short-load charge before ordering.
Should I round up the amount of concrete I order?
Yes. Ready-mix suppliers commonly recommend ordering 5-10% over the calculated volume to cover an uneven sub-grade, formwork that bows slightly under pressure, and spillage — running short mid-pour forces either a rushed second truck or a cold joint, both worse than a small leftover. Toggle the waste allowance on this calculator to add that buffer automatically.
Does the cost estimate include labor, forms, rebar, or a gravel base?
No — the price shown is material cost only, at the per-cubic-yard rate you enter. Labor for forming and finishing, rebar or wire mesh reinforcement, and a compacted gravel sub-base are separate line items that vary by region and project, so budget for them in addition to the material cost shown here.
What depth should I use for a typical concrete pour?
4 inches is standard for patios, walkways, and shed pads under light foot traffic. Driveways and any surface carrying vehicle weight typically need 5-6 inches, and structural elements like footings or foundation walls are sized by an engineer or local code rather than a rule of thumb — never guess depth on a load-bearing pour.
Estimates only. Verify quantities with your supplier before purchasing.