40 lb Bag of Concrete: How Much Does It Make?
One 40 lb bag of standard concrete mix makes about 0.30 cubic feet (0.0111 yd³, 8 liters). It takes 90 bags to make a cubic yard.
- Yield0.30 ft³
- Bags per yd³90
- Covers at 4 in0.90 sq ft
- Bags per 100 sq ft at 4 in112
Concrete needed
1.36 cubic yards
36.7 ft³ · 1.04 m³ · includes 10% extra
You need about 1.36 cubic yards of concrete, or 123 bags of 40 lb mix.
Bags of premix
- 12340 lb bags
- 9850 lb bags
- 8260 lb bags
- 6280 lb bags
- —20 kg bags
- —25 kg bags
- Before extra1.23 yd³ (33.3 ft³)
- Weight of bags4,920 lb
- Per hole—
- Ready-mix costAdd a price per yd³
- Bagged costAdd a price per bag
One 40 lb bag makes about 0.30 ft³ (manufacturer's published yield). Bags are rounded up.
At 1.36 yd³ (62 × 80 lb bags, 4,960 lb), bags and a small ready-mix load are both reasonable. Ask local suppliers for their minimum load and short-load fee before deciding.
Estimate only, not a quote or engineering advice. Disclaimer
The 40-lb bag is the smallest common size, handy for a single post, a repair or a stepping stone. For anything bigger it means a lot of bags: 90 per cubic yard.
Coverage of one 40 lb bag
| Thickness | Sq ft per bag | Bags per 100 sq ft |
|---|---|---|
| 2 in | 1.80 | 56 |
| 3 in | 1.20 | 84 |
| 4 in | 0.90 | 112 |
| 5 in | 0.72 | 139 |
| 6 in | 0.60 | 167 |
40 lb bags for a given volume
| Volume | ft³ | Bags | Total weight (lb) |
|---|---|---|---|
| 0.25 yd³ | 6.75 | 23 | 920 |
| 0.5 yd³ | 13.50 | 45 | 1,800 |
| 1 yd³ | 27.00 | 90 | 3,600 |
| 1.5 yd³ | 40.50 | 135 | 5,400 |
| 2 yd³ | 54.00 | 180 | 7,200 |
| 3 yd³ | 81.00 | 270 | 10,800 |
Common jobs
- 10 × 10 ft slab, 4 in thick, +10%: 123 bags (details)
- 12 × 12 ft slab, 4 in thick, +10%: 176 bags (details)
- 4×4 fence post in a 10 × 24 in hole: 4 bags (details)
Water per bag
QUIKRETE's data sheet for its Concrete Mix gives a starting amount of 3 pt (1.4 L) of water per 40 lb bag, up to about 4½ pt (2.1 L). Add water a little at a time; too much makes weaker concrete.
Yields are for standard concrete mix. Fast-setting, high-strength and crack-resistant mixes may yield differently, so check the bag you buy. Other sizes: 50 lb, 60 lb, 80 lb.
Frequently asked questions
How many cubic feet in a 40 lb bag of concrete?
About 0.30 cubic feet, according to the QUIKRETE Concrete Mix data sheet.
How many 40 lb bags of concrete in a yard?
90. A cubic yard is 27 ft³, and 27 ÷ 0.300 = 90.0.
How much area does a 40 lb bag of concrete cover?
About 0.90 sq ft at 4 inches thick, 1.20 sq ft at 3 inches or 1.80 sq ft at 2 inches.
How many 40 lb bags for a fence post?
A 4×4 post in a 10-inch hole 24 inches deep takes 4 bags of 40 lb mix. Use the post hole calculator for your hole size.
Related
Sources
- QUIKRETE: Concrete Mix No. 1101 data sheet (Revised Oct 2022; checked Nov 11, 2026)