Concrete & Masonry
Quick Reference
| Bag size | Yield (ft³) | Bags per yard |
|---|---|---|
| 40 lb | 0.30 ft³ | 90 |
| 60 lb | 0.45 ft³ | 60 |
| 80 lb | 0.60 ft³ | 45 |
| 90 lb | 0.68 ft³ | 40 |
Bags = ceil(cubic_yards × 27 ÷ bag_yield_ft³). Always add 5–10% for spillage and uneven sub-grade.
0.05 yd³ × 27 = 1.35 ft³ → 3 bags of 60 lb or 3 bags of 80 lb.
1.23 yd³ × 27 = 33.3 ft³ → 75 bags of 60 lb. Use ready-mix delivery instead.
About 1.05 ft³ → 3 bags of 60 lb or 2 bags of 80 lb.
Related questions
45 bags of 80 lb pre-mix yield exactly 1 cubic yard. Always order 47–48 to allow for spillage.
Most bagged pre-mix is 4,000 PSI, equal to or stronger than typical ready-mix. The difference is consistency — ready-mix is mixed to a precise water/cement ratio.
Above about 0.5 yd³ (or 25 bags of 80 lb). Beyond that, mixing time and cost makes ready-mix the better choice.
Once water is added: 30–45 minutes before it starts to set. Unopened bags last 6–12 months in dry storage; longer with moisture barrier.
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