Concrete Calculator
Calculate cubic yards and standard 60lb/80lb concrete bag quantities for slabs, footings, and steps.
⚙️ Slab Dimensions
📊 Material Estimate
Cubic Yards Required
1.48 cu yd
Estimated 80lb Bags: ~64 bags
| Material Metric | Quantity |
|---|---|
| Cubic Yards (cu yd) | 1.48 |
| Cubic Feet (cu ft) | 40.0 |
| 60 lb Bags Needed | 85 bags |
| 80 lb Bags Needed | 64 bags |
How to Use This Calculator
- Step 1: Enter slab length, width, and thickness in inches to calculate cubic yards and bag quantities.
Formula & Calculation Method
Cubic Feet = Length × Width × (Depth in inches / 12) | Cubic Yards = Cubic Feet / 27
Where the variables represent:
| Variable | Description & Units |
|---|---|
| Length & Width | Slab dimensions in feet |
| Depth | Thickness in inches |
Worked Calculation Example
Scenario:
Slab measuring 12 ft by 10 ft with a 4-inch thickness.
- Depth in feet = 4 / 12 = 0.333 ft
- Cubic feet = 12 × 10 × 0.333 = 40 cu ft
- Cubic yards = 40 / 27 = 1.48 cu yd
Result: Requires 1.48 cubic yards (approx. 64 bags of 80lb concrete).
Frequently Asked Questions
Should I buy extra concrete bags?
Yes, it is standard practice to add a 5% to 10% overage allowance for spills or subgrade unevenness.
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Accuracy & General Guidance Disclaimer: This calculation tool is provided for educational and practical planning purposes. Formulas are verified against standard mathematical models. Do not rely on estimates as certified professional, financial, legal, or medical advice.