Concrete Calculator
Calculate the exact amount of concrete needed for your construction project, including volume, weight, and cost estimation.
Enter dimensions and click calculate to see results.
How It Works
How This Calculator Works
This calculator determines concrete volume by multiplying length × width × depth for rectangular areas, or πr² × depth for circular slabs. The calculator converts all units to a standard measure before calculating and includes options for adding a waste factor and calculating costs.
The Formula
For rectangular areas:
Volume = Length × Width × Depth
For circular areas:
Volume = π × (Diameter/2)² × Depth
With waste factor:
Adjusted Volume = Volume × (1 + Waste%/100)
Weight calculation:
Weight = Volume × Density
Cost calculation:
Cost = Volume × Price per unit volume
Important Considerations
- Always add a 5-10% waste factor for spillage and uneven ground
- Standard concrete density is approximately 150 lbs/ft³ (2,400 kg/m³)
- For structural applications, always consult with a structural engineer
- Concrete typically requires 24-48 hours to set initially and 28 days to cure fully
Frequently Asked Questions
How many bags of concrete mix do I need for a cubic yard?
A cubic yard of concrete requires approximately 90 bags of 40-pound concrete mix, 60 bags of 60-pound mix, or 45 bags of 80-pound mix.
What's the difference between concrete and cement?
Cement is one ingredient in concrete. Concrete is a mixture of cement, water, sand, and aggregates. Cement acts as a binding agent when mixed with water and aggregates.
How long does concrete take to cure?
Concrete typically sets initially in 24-48 hours, allowing for light foot traffic, but it takes approximately 28 days to cure to its full strength under normal conditions.
What if my concrete area has an irregular shape?
For irregular shapes, divide the area into simpler geometric shapes (rectangles, circles), calculate the volume for each part separately, and then add them together for the total volume.