Concrete Calculator
Calculate concrete volume and bag estimates for slabs, columns, and stairs. Get results in cubic yards, cubic meters, and cubic feet. Find how many 60 lb or 80 lb bags you need for your construction project.
Estimate the volume of concrete needed for your project. Choose the shape, enter dimensions, and calculate volume in cubic yards, cubic meters, and cubic feet. Get the number of bags needed for 60 lb and 80 lb bag sizes.
Formula
Slab: V = L × W × (T/12) | Cylinder: V = π × (D/2)² × H | Stairs: V = (L × W × H) / 2
Volume formulas for rectangular slabs, cylindrical columns, and triangular stair structures. All dimensions in feet except thickness (inches). Convert cubic feet to cubic yards by dividing by 27. Each cubic yard requires approximately 45 bags of concrete at standard mix (60 lb bags) or 60 bags (80 lb bags).
Frequently Asked Questions
Use this in your workflow
Pair concrete volume estimates with the Density Calculator to verify material weight. Use the Volume Calculator for other 3D shapes. Browse all Free Construction Calculators.
When to use this calculator
- →Estimating material for a warehouse floor slab or foundation pour
- →Planning a concrete staircase installation or repair
- →Calculating concrete volume for support columns or cylindrical structures
- →Building a project budget with material quantity and cost estimates
Worked example: 1,000 sq ft warehouse floor
A typical facility improvement scenario.
| Item | Value |
|---|---|
| Slab area | 1,000 sq ft |
| Slab dimensions | 50 ft × 20 ft |
| Thickness | 4 inches |
| Volume (cubic feet) | 6,667 cu ft |
| Volume (cubic yards) | 247 cu yd |
| Bags (60 lb) | 11,115 bags |
| Bags (80 lb) | 14,820 bags |
For a standard 4-inch warehouse floor, 247 cubic yards requires approximately 11,115 bags at 60 lb each. Add 10–15% for waste and spillage. Consult your supplier for final pricing and delivery logistics.
Limitations
This calculator provides theoretical volume based on the dimensions entered. Actual concrete needed may vary due to on-site conditions, ground settling, reinforcement steel, and measurement error. Always add 10–15% contingency for waste. For complex or irregular shapes, break the project into simpler geometric components and calculate separately. Results are for planning purposes — consult with contractors or suppliers for final project estimates and specifications.
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Frequently asked questions
How much concrete do I need?
Enter your project dimensions using this calculator. For slabs, enter length, width, and thickness (in inches). The calculator provides volume in cubic yards, cubic meters, and cubic feet, plus the number of 60 lb and 80 lb bags required.
What's the standard thickness for concrete slabs?
Standard warehouse or facility floors are typically 4–6 inches thick. Residential driveways are 3–4 inches. Parking lots are 4–8 inches. Check local building codes and consult with contractors for your specific application.
How many bags of concrete do I need?
Multiply your cubic yards by 45 to get 60 lb bags, or by 60 for 80 lb bags. This calculator does that conversion automatically. Always add 10–15% extra for spillage and waste.
What is a cubic yard?
A cubic yard is 3 feet × 3 feet × 3 feet = 27 cubic feet. It's a standard unit for ordering concrete from suppliers. One cubic yard of concrete weighs approximately 3,700–4,000 pounds.
Can I use this for irregular shapes?
Break irregular shapes into simpler components (rectangles, cylinders, triangles). Calculate the volume of each part separately and add the results together for a total estimate.
Is this estimate accurate for real projects?
This calculator provides theoretical volume. Actual material needed may differ due to ground conditions, reinforcement steel, measurement error, and spillage. Always add 10–15% contingency and verify with your contractor or supplier.