Concrete Slab & Gravel Volume Calculator
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How to Use the Concrete Calculator
Enter the length, width, and thickness of your slab. The calculator handles both concrete (in bags) and gravel (in tons). It includes a wastage factor so you order enough material.
- Concrete: Results show cubic yards, cubic feet, and number of bags
- Gravel: Results show cubic yards, cubic feet, and estimated tons
- Wastage: Add 5-15% extra depending on ground conditions
Concrete Volume Formula
Volume (cu yd) = Length (ft) × Width (ft) × Depth (in) ÷ 324
One cubic yard of concrete covers 81 sq ft at 4 inches thick. Standard ready-mix trucks hold 10-12 cubic yards.
Frequently Asked Questions
For a 10'x10' slab at 6" thick: (10 x 10 x 6) / 324 = 1.85 cu yd. With 10% wastage, order about 2.04 cu yd — roughly 12 bags of 80-lb mix.
For projects under 2 cubic yards, bags are cost-effective. For larger slabs, order ready-mix. A standard truck carries 10-12 yards with a minimum of 3-4 yards.
A typical driveway uses 4-6 inches of gravel base. For a 20'x30' driveway at 6" deep: (20 x 30 x 6) / 324 = 11.1 cu yd — about 15 tons.