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How Much Concrete for a 30x40 Slab?
A 30 × 40 ft slab at 4 in thick needs 16.3 yd³ (440 ft³ · 12.46 m³ incl. 10% waste).
How Much Concrete for a 30x40 Slab?
Concrete needed440 ft³ · 12.46 m³ incl. 10% waste
80 lb bags (0.60 ft³ each)
734
60 lb bags (0.45 ft³ each)
978
40 lb bags (0.30 ft³ each)
1467
Ready-mix trucks (~9 yd³)
1.8
Ready-mix suppliers usually sell in ¼ or ½ yd³ steps with a minimum order. Slabs on grade are typically 4 in for patios/walks and 5–6 in for driveways.
Planning estimates only. Building codes, loads and material specs vary — have a licensed engineer or contractor confirm quantities and safety requirements. Disclaimer
By thickness
- 4 in: 16.3 yd³
- 5 in: 20.37 yd³
- 6 in: 24.44 yd³
- 8 in: 32.59 yd³
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