Concrete Calculator
Work out how much concrete a slab, column or round footing needs — volume in cubic yards and cubic meters, plus how many 80 lb or 60 lb bags to buy with a 10% safety margin. Order slightly more than estimated; running short mid-pour is a real problem.
TheCalculators — Concrete Calculator
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Concrete Needed
2.04 yd³
10 × 10 × 0.5 ft × 1 · includes 10% waste · 1.42 m³
- Volume (exact)
- 50 ft³ = 1.85 yd³
- Metric
- 1.42 m³
- +10% Waste
- 2.04 yd³
- 80 lb Bags
- 92 bags (7,360 lb)
- 60 lb Bags
- 123 bags (7,380 lb)
- Ready-Mix Equivalent
- 2.04 yd³ (truck minimum is usually 1 yd³)
Volume with waste margin
- Exact volume (yd³)1.85
- 10% waste margin0.19
Slab coverage guide (per cubic yard, 1 yd³)
An 80 lb bag yields ~0.60 ft³ (0.022 yd³); a 60 lb bag ~0.45 ft³ (0.017 yd³). Your project needs 50 ft³ before waste.
Always order ~5–10% extra — subgrade unevenness and spillage eat margin fast, and a cold joint from a mid-pour shortage weakens the slab permanently.
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Formula
Slab: V = l × w × h × qty · Round: V = π × (d/2)² × h × qty · Bags = V(with 10% waste) ÷ bag yield
- • Compute the geometric volume of one element in cubic feet.
- • Multiply by quantity, convert: ÷27 for cubic yards, ×0.0283168 for cubic meters.
- • Add 10% waste and divide by bag yield: 0.6 ft³ (80 lb) or 0.45 ft³ (60 lb), rounding up.
Pro tips
- • Standard driveway slab: 4 in thick (0.33 ft); patios 4 in; footings below frost line per code.
- • One cubic yard covers 81 sq ft at 4 inches thick.
- • Bagged concrete suits small jobs; over ~1 yd³ a ready-mix truck is cheaper and faster.
FAQ
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