Concrete Calculator
Planning a concrete project? Calculate exactly how much material you need. Enter the dimensions of your slab, footing, or post holes to get the cubic yards of ready-mix concrete or number of bags required. Includes waste factor for accurate ordering.
How We Calculate This
Volume = Length x Width x (Depth/12) in cubic feet. Divide by 27 for cubic yards. 80 lb bag yields 0.6 cu ft. 60 lb bag yields 0.45 cu ft. Waste factor added to total.
Frequently Asked Questions
How much does a cubic yard of concrete cover?
At 4 inches thick, one cubic yard covers 81 square feet. At 6 inches thick, it covers 54 square feet. At 3 inches thick, it covers 108 square feet.
How many bags of concrete are in a cubic yard?
Approximately 45 bags of 80 lb concrete or 60 bags of 60 lb concrete make one cubic yard. For large projects, ordering ready-mix by the yard is more economical.
How thick should a concrete slab be?
4 inches is standard for patios and walkways. Driveways should be 5-6 inches. Garage floors typically need 4-6 inches. Heavy traffic areas may need reinforcement.
Should I add extra concrete?
Yes, add 5-10% extra for waste, spillage, and uneven subgrade. For complex shapes or sloped ground, add 15%. Its better to have a little extra than to run short.
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