This concrete calculator helps you determine exactly how much concrete you need for your project. Whether you're pouring a slab, foundation, or driveway, accurate calculations prevent waste and ensure you have enough material.
Concrete is typically measured in cubic yards. One cubic yard equals 27 cubic feet. For standard 80-pound bags of concrete mix, you'll need approximately 45 bags per cubic yard. Most slabs require 4 inches (0.33 feet) of thickness, while foundations may need 6-8 inches.
To use this calculator, measure the length and width of your area in feet, then enter the desired depth. The calculator automatically converts to cubic yards and tells you how many bags to purchase. Always buy 10% extra to account for spillage and uneven ground.
Remember that concrete has a limited working time once mixed, typically 90 minutes. Plan your pour carefully and have helpers ready. For large projects over 2 cubic yards, consider ordering ready-mix concrete delivered by truck.
Quick Tips
- Always order 10-15% extra materials for waste
- Check local building codes before starting
- Measure twice, cut once — verify all inputs
Frequently Asked Questions
Standard slabs are 4 inches thick. Driveways and heavy-use areas should be 6 inches. Foundations typically require 8-12 inches.
Approximately 45 bags of 80-pound concrete mix equal one cubic yard.
Slabs over 4 inches thick or subject to heavy loads should include rebar or wire mesh reinforcement.
Concrete reaches walking strength in 24-48 hours but takes 28 days to reach full strength.
Avoid pouring when temperatures drop below 40F. Cold weather slows curing and can damage the concrete.