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The Concrete Calculator helps contractors and DIYers estimate the concrete needed for slabs, footings, walls, and other applications. Get accurate volume calculations in cubic yards or cubic feet, plus bag counts for smaller projects.
Accurate concrete estimation prevents costly over-ordering or project-delaying shortages. Enter your dimensions to calculate exact volumes, then add a waste factor for practical ordering.
The calculator handles rectangular slabs, circular columns, footings, and walls. For complex shapes, break them into simple components and add the results.
Features
Everything you need
- Slab volume calculations
- Footing and wall estimates
- Circular column support
- Cubic yards and cubic feet output
- Bag count for small projects
- Adjustable waste factor
- Multiple shape support
How it works
Simple workflow
- 1Select the concrete application type
- 2Enter length, width, and thickness dimensions
- 3Add a waste factor percentage (typically 5-10%)
- 4Review the volume in cubic yards
- 5See bag count for smaller quantities
Use cases
Built for real-world scenarios
Driveway and patio slabs
Calculate concrete volume for flatwork with proper waste allowance.
Foundation footings
Estimate continuous and spread footing volumes for residential foundations.
Concrete walls
Calculate volume for basement walls, retaining walls, and stem walls.
Material ordering
Convert volume to ready-mix truck loads or bag counts for ordering.
FAQ
Frequently asked questions
An 80-lb bag yields about 0.6 cubic feet. For 1 cubic yard (27 cubic feet), you need approximately 45 bags of 80-lb concrete. For 60-lb bags, you need about 60 bags per cubic yard.
Typical thicknesses: 4 inches for patios and walkways, 4-6 inches for driveways, and 4-6 inches for garage floors. Heavy vehicle traffic may require 6-8 inches with reinforcement.
Order 5-10% extra for waste, spillage, and over-excavation. For complex shapes or multiple pours, consider 10-15% overage. Ready-mix minimums typically start at 1-2 cubic yards.
Use the formula: Volume = π × radius² × height. For a 12-inch diameter, 10-foot column: V = 3.14 × 0.5² × 10 = 7.85 cubic feet, or about 0.29 cubic yards.
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We're always looking to improve our calculators. If you have ideas for new features, improvements, or found something that could work better, we'd love to hear from you.
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