Concrete Calculator
Calculate cubic yards, cubic feet, and bags needed for any concrete project
Coverage Reference Table
How many square feet does 1 cubic yard cover at different thicknesses?
| Thickness | 1 Cubic Yard Covers | Common Use |
|---|---|---|
| 2 inches | 162 sq ft | Topping slabs, thin overlays |
| 3 inches | 108 sq ft | Light-duty paths |
| 4 inches | 81 sq ft | Sidewalks, patios, garage floors |
| 5 inches | 65 sq ft | Light driveways |
| 6 inches | 54 sq ft | Driveways (cars & trucks) |
| 8 inches | 40 sq ft | Heavy equipment slabs, footings |
| 10 inches | 32 sq ft | Deep footings, retaining walls |
| 12 inches | 27 sq ft | Heavy structural footings |
Bag Count Reference Table
| Cubic Yards | Cubic Feet | 60 lb Bags | 80 lb Bags | Order Ready-Mix? |
|---|---|---|---|---|
| 0.25 yd³ | 6.75 cu ft | 15 bags | 12 bags | No — use bags |
| 0.5 yd³ | 13.5 cu ft | 30 bags | 23 bags | No — use bags |
| 1 yd³ | 27 cu ft | 60 bags | 45 bags | Borderline |
| 2 yd³ | 54 cu ft | 120 bags | 90 bags | ✅ Consider ready-mix |
| 3 yd³ | 81 cu ft | 180 bags | 135 bags | ✅ Ready-mix recommended |
| 5 yd³ | 135 cu ft | 300 bags | 225 bags | ✅ Ready-mix |
| 10 yd³ | 270 cu ft | 600 bags | 450 bags | ✅ Ready-mix only |
Ready-mix vs bags: For projects over 1 cubic yard, ready-mix concrete is usually more cost-effective. A truck delivers $125–$200/yard. Bags cost ~$5–8 each = $300–$480 per cubic yard — 2–3× more expensive, plus mixing labor.
Recommended Slab Thickness by Project
| Project | Thickness | Notes |
|---|---|---|
| Sidewalk / Walkway | 4 inches | Standard residential |
| Patio | 4 inches | 4 in min; 6 in if near trees |
| Garage floor | 4–6 inches | 6 in for heavier vehicles |
| Residential driveway | 4–6 inches | 6 in recommended |
| Truck / RV driveway | 6 inches | Rebar required |
| Shed floor | 3.5–4 inches | Vapor barrier underneath |
| Pool deck | 4 inches | Non-slip finish required |
| Foundation footing | 8–12 inches | Per structural engineer |
| Deck footing (tube) | 10–12 in dia | Below frost line depth |
How to Calculate Concrete — Formulas
Frequently Asked Questions
How do I calculate how much concrete I need?
Multiply length (ft) × width (ft) × thickness (ft) to get cubic feet, then divide by 27 to get cubic yards. Convert inches to feet by dividing by 12. Always add 10% for waste. Use the calculator above for instant results.
How many bags of concrete do I need for a 10×10 slab?
A 10×10 ft slab at 4 inches thick = 33.3 cubic feet + 10% waste = 36.7 cubic feet. That's 82 bags of 60 lb (0.45 cu ft each) or 62 bags of 80 lb (0.60 cu ft each). Use the calculator for your exact dimensions.
How many cubic yards are in a truck?
A standard ready-mix concrete truck holds 8–10 cubic yards. Minimum orders are often 1 cubic yard with a short-load fee. For projects under 1 yard, bags are usually more practical.
Why add 10% for waste?
Concrete volume calculations assume perfectly level, square forms. In reality: sub-base is uneven, some concrete spills, and you need extra to ensure you don't run short mid-pour. Running out creates cold joints that can crack. Always order extra.
How thick does a concrete driveway need to be?
4 inches is the minimum for residential driveways with passenger cars. 6 inches is recommended for trucks, SUVs, or heavier vehicles. Add rebar or fiber reinforcement for driveways thicker than 4 inches.