Concrete Calculator
Take the stress out of your next patio, sidewalk, or post hole pour. Ensure you buy exactly enough by entering your dimensions below to calculate total cubic yards and specific 60 lb or 80 lb bag quantities.
How It Works
Our calculator converts your project dimensions into cubic yards using the formula: Volume (ft³) = Length × Width × (Depth ÷ 12). It then divides by 27 to get cubic yards. Bag count is derived from the yield per bag (0.45 ft³ for 60lb bags, 0.60 ft³ for 80lb bags), including a 10% safety buffer to account for uneven ground and spillage.
When to Use This
Use this before any concrete pour project: fence posts, sidewalks, patios, or slabs. Always buy slightly more than your calculation shows, as running out of concrete mid-pour is a common and costly mistake.
How it Works
- 1
Measure the Slab Size
Determine the length and width of your project area in feet.
- 2
Determine Depth
Choose your depth in inches. Standard patios and sidewalks are typically 4 inches thick.
- 3
Review the Estimate
The tool instantly returns the bulk volume in cubic yards, while estimating exact bag counts (incorporating a 10% safety buffer).
| Slab Size (ft) | Volume Required | Estimated 80lb Bags |
|---|---|---|
| 5' × 5' | 0.31 yd³ | 16 bags (80lb) |
| 10' × 10' | 1.23 yd³ | 62 bags (80lb) |
| 12' × 12' | 1.78 yd³ | 88 bags (80lb) |
| 20' × 10' | 2.47 yd³ | 123 bags (80lb) |
| 20' × 20' | 4.94 yd³ | 245 bags (80lb) |
Frequently Asked Questions
How much does an 80 lb bag of concrete cover?
Why should I add a 10% buffer?
Should I buy bags or order a truck?
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