How Many Bags of Concrete Are in a Yard?
Bags per Cubic Yard
| Bag size | Yield | Bags per yd³ | Water per bag |
|---|---|---|---|
| 80-lb bag | 0.60 ft³ | 45 bags | ≈ 2.5–3 qt water each |
| 60-lb bag | 0.45 ft³ | 60 bags | ≈ 2–2.5 qt water each |
| 40-lb bag | 0.30 ft³ | 90 bags | ≈ 1.5 qt water each |
Always round up to whole bags — 44.6 bags of coverage means 45, and the math above is before the standard +10% ordering cushion.
How Many 80-lb Bags for Common Projects?
| Project | Volume | 80-lb bags |
|---|---|---|
| 10 × 10 ft pad, 4 in. | 33.3 ft³ → 1.23 yd³ | 56 bags (62 with +10%) |
| 12 × 20 ft slab, 4 in. | 80 ft³ → 2.96 yd³ | 134 bags (147 with +10%) |
| ½ cubic yard | 13.5 ft³ | 23 × 80-lb bags |
| Sonotube 12 in. × 4 ft | 3.14 ft³ | 6 × 80-lb bags |
Counts use the 45-bags-per-yard figure; the parenthetical adds the 10% cushion for uneven subgrade and spillage.
Where Bags Stop Making Sense
Forty-five bags is one cubic yard — and roughly one full day of mixing for two people, at 3,591 lb of dry material hauled and mixed in wheelbarrow batches. Somewhere around the one-yard mark the decision flips to delivered ready-mix, which at typical prices is also nearly half the cost per yard. Bags own the small end: piers, post holes, pads and repairs under about a yard, where a truck's short-load fee would dwarf the concrete itself.
Frequently Asked Questions
How many 80-lb bags of concrete are in a yard?
Exactly 45 — one 80-lb bag yields 0.60 ft³ of mixed concrete and a yard is 27 ft³, so 27 ÷ 0.60 = 45. For a real order, add the 10% cushion: 50 bags per yard.
How many bags do I need for a 12×20 slab?
At 4 inches thick, a 12 × 20 ft slab is 80 ft³, or 2.96 cubic yards — 134 of the 80-lb bags, or 147 with the 10% allowance. That's a two-person, full-day mixing job and a strong argument for a ready-mix truck.
How many 60-lb bags equal one 80-lb bag?
About 1⅓ — an 80-lb bag yields 0.60 ft³ against the 60-lb bag's 0.45 ft³ (0.60 ÷ 0.45 = 1.33). The same ratio holds against 40-lb bags: one 80-lb bag equals two of them.
Is it cheaper to buy bags or order concrete by the yard?
Per yard, bags cost roughly twice as much ($290–$325 vs $150–$180 delivered). Bags win only where a short-load fee would apply anyway — small pours under about a yard — or where a truck simply can't reach.