Concrete Bag Chart
One cubic yard is forty-five 80 pound bags — about 3,600 pounds to carry and mix. That figure is the reason most projects switch to ready-mix long before they reach a full yard.
Generated from the same data the calculators use — a chart and a calculator on this site cannot disagree.
Bags per volume
| Bag size | Yield per bag | Bags per ft³ | Bags per cubic yard |
|---|---|---|---|
| 40 lb | 0.30 ft³ | 3.3 | 90 |
| 50 lb | 0.375 ft³ | 2.7 | 72 |
| 60 lb | 0.45 ft³ | 2.2 | 60 |
| 80 lb | 0.60 ft³ | 1.7 | 45 |
Common pours — volume and 80 lb bag count, before waste
| Pour | Volume | Cubic yards | 80 lb bags |
|---|---|---|---|
| Post hole, 8" × 36" | 1.05 ft³ | 0.04 | 2 |
| Post hole, 12" × 36" | 2.36 ft³ | 0.09 | 4 |
| Pad, 24" × 24" × 8" | 2.67 ft³ | 0.10 | 5 |
| Slab, 4 ft × 4 ft × 4" | 5.33 ft³ | 0.20 | 9 |
| Slab, 10 ft × 10 ft × 4" | 33.3 ft³ | 1.23 | 56 |
| Slab, 12 ft × 20 ft × 4" | 80.0 ft³ | 2.96 | 134 |
How to read this chart
Around half a cubic yard, ready-mix becomes both cheaper and better. Most suppliers have a one yard minimum plus a short-load fee, and it is still usually less than the bags — before counting a day of mixing.
The quality argument matters more than the cost one. Hand-mixed batches vary in water content, and water content is the single biggest determinant of concrete strength. A slab poured in twenty batches over four hours has twenty different strengths and cold joints between them.
Order over rather than under. Fresh concrete placed against concrete that has started to set does not bond, creating a permanent plane of weakness. In warm weather that window closes in under an hour — long enough for a trip to the supplier to ruin a pour.
Cured normal-weight concrete weighs about 145 lb per cubic foot, so a 10 × 10 foot slab at 4 inches is close to 4,800 pounds. Check what the forms and subgrade are carrying.
Sources
- Standard bag yields: 40 lb ≈ 0.30 ft³, 60 lb ≈ 0.45 ft³, 80 lb ≈ 0.60 ft³
- Normal-weight concrete at approximately 145 lb per cubic foot
Reference values. Bag yields vary slightly by manufacturer and mix. Confirm against the bag you are buying.
Frequently asked questions
How many 80 lb bags are in a cubic yard?
Forty-five. A cubic yard is 27 cubic feet and an 80 pound bag yields about 0.6 cubic feet.
When should I order ready-mix?
Around half a cubic yard is the practical crossover. Below that, bags are convenient. Above it, ready-mix is usually cheaper, more consistent, and finishes in one continuous pour.
How much waste should I allow?
Ten percent for a formed slab, twenty for holes in rough ground. Subgrade dips, forms bow and post holes are always over-excavated.
Can I mix bags in a wheelbarrow?
For a few bags, yes. Beyond about ten, a powered mixer pays for its rental in consistency alone — hand mixing tends to add water to make the job easier, which directly weakens the concrete.