How Many Bags of Concrete for a 6-Inch Wide, 42-Inch Deep Hole?
Short answer for a 6-inch diameter, 42-inch deep hole: about 2 bags (80-lb bags of concrete mix). Also: 60-lb bags: 2 bags; 50-lb bags: 3 bags; cubic feet (exact): 0.69 ft³.
Concrete Footing & Post Hole Calculator
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| 60-lb bags | 2 bags |
|---|---|
| 50-lb bags | 3 bags |
| Cubic feet (exact) | 0.69 ft³ |
| Cubic yards (+10%) | 0.028 yd³ |
How this number is calculated
Volume of a cylinder: π × (6 ÷ 2 ÷ 12)² × (42 ÷ 12) = 0.69 cubic feet. Add 10% waste, then divide by 0.6 cubic feet per 80-lb bag: 2 bags.
Nearby sizes
| Size | 80-lb bags of concrete mix |
|---|---|
| a 6-inch diameter, 36-inch deep hole | 2 bags |
| a 6-inch diameter, 48-inch deep hole | 2 bags |
| a 6-inch diameter, 24-inch deep hole | 1 bags |
| a 6-inch diameter, 30-inch deep hole | 1 bags |
See every size for the concrete footing & post hole calculator →
Tips
- Subtract the volume of the post itself if you want a tighter number; it is ignored here to stay on the safe side.
- A common rule is a hole depth of about one third of the post's total length, but local frost depth and code may require more.
- Use the hole's actual diameter, which is usually wider than the post.
Frequently asked questions
How much concrete do I need for a 6-inch diameter, 42-inch deep hole?
Short answer for a 6-inch diameter, 42-inch deep hole: about 2 bags (80-lb bags of concrete mix). Also: 60-lb bags: 2 bags; 50-lb bags: 3 bags; cubic feet (exact): 0.69 ft³.
How is the quantity for a 6-inch diameter, 42-inch deep hole calculated?
Volume of a cylinder: π × (6 ÷ 2 ÷ 12)² × (42 ÷ 12) = 0.69 cubic feet. Add 10% waste, then divide by 0.6 cubic feet per 80-lb bag: 2 bags.
How much does concrete for a 6-inch diameter, 42-inch deep hole cost?
Using rough planning prices (per 80-lb bag, typical retail), the material for a 6-inch diameter, 42-inch deep hole comes to about $10.00 to $18.00. Prices vary by region and supplier, so get a local quote.