🏗️ Concrete Calculator
Calculate concrete volume for slabs, footings, columns, and more
📏 Slab Dimensions
📊 Results
Concrete Volume
Cubic Feet
Cubic Meters
60 lb Bags
80 lb Bags
📏 Footing Dimensions
📊 Results
Concrete Volume
Cubic Feet
Cubic Meters
60 lb Bags
80 lb Bags
📏 Column Dimensions
📊 Results
Concrete Volume
Cubic Feet
Cubic Meters
60 lb Bags
80 lb Bags
📚 Understanding Concrete Calculations
What is Concrete?
Concrete is a composite material made from cement, water, sand, and aggregate (gravel or crushed stone). It's one of the most widely used construction materials due to its strength, durability, and versatility.
How to Calculate Concrete Volume
- Slabs: Volume = Length × Width × Thickness
- Footings: Volume = Length × Width × Depth
- Columns: Volume = π × (Diameter/2)² × Height
- Convert to cubic yards: Divide cubic feet by 27
Concrete Bag Coverage
- 60 lb bag: Covers approximately 0.45 cubic feet (0.017 cubic yards)
- 80 lb bag: Covers approximately 0.60 cubic feet (0.022 cubic yards)
- Tip: Always order 5-10% extra to account for waste and spillage
Standard Concrete Thickness
- Sidewalks: 4 inches thick
- Driveways: 4-6 inches thick
- Garage floors: 6 inches thick
- Footings: 8-12 inches deep, width varies by load
- Basement walls: 8-10 inches thick
Tips for Ordering Concrete
- Always round up to the nearest quarter yard when ordering
- Add 5-10% extra for waste, spillage, and uneven subgrade
- Consider the concrete strength (PSI) needed for your project
- Check if you need special additives (air entrainment, accelerators, etc.)
- Ensure proper site access for concrete trucks
- Have enough workers ready for placement and finishing
Frequently Asked Questions
How much does a cubic yard of concrete weigh?
A cubic yard of concrete typically weighs about 4,000 pounds (2 tons) when wet and slightly less when cured. The exact weight depends on the mix design and aggregate used.
How many 80 lb bags of concrete do I need for 1 cubic yard?
You'll need approximately 45 bags of 80 lb concrete to make 1 cubic yard. For 60 lb bags, you'll need about 60 bags per cubic yard.
Should I use bags or ready-mix concrete?
For projects requiring less than 1 cubic yard, bags are convenient. For larger projects (1+ cubic yards), ready-mix concrete delivered by truck is more economical and ensures consistent quality.
How thick should my concrete slab be?
Standard thickness varies by application: 4 inches for sidewalks and patios, 4-6 inches for driveways, and 6 inches for garage floors. Heavier loads require thicker slabs.
How much extra concrete should I order?
Always order 5-10% extra concrete to account for spillage, uneven subgrade, and measurement variations. It's better to have a little extra than to run short during the pour.
What PSI concrete do I need?
Common PSI ratings: 2,500 PSI for residential footings, 3,000 PSI for driveways and slabs, 3,500-4,000 PSI for heavy-duty applications. Consult local building codes for specific requirements.
How long does concrete take to cure?
Concrete reaches about 70% strength in 7 days and 90% in 28 days. You can typically walk on it after 24-48 hours, but wait at least 7 days before driving on it.