Concrete Bag Quantity Calculator

Find out exactly how many bags of concrete mix you need for your project. Supports 40 lb, 60 lb, and 80 lb bags.

Frequently Asked Questions

How many bags of concrete do I need for a 10x10 slab?
For a 10×10 ft slab at 4 inches thick (33.3 cubic feet), you would need approximately 111 bags of 60 lb mix or 56 bags of 80 lb mix. This includes a 10% waste factor. Actual needs vary based on bag brand yield.
What is the difference between 40 lb, 60 lb, and 80 lb concrete bags?
The difference is the amount of concrete each bag yields: 40 lb bags yield ~0.30 cubic feet, 60 lb bags yield ~0.45 cubic feet, and 80 lb bags yield ~0.60 cubic feet. Larger bags are more cost-effective for big projects.
Should I add extra concrete for waste?
Yes, always add 10-15% extra for waste, spillage, and uneven surfaces. Simple rectangular slabs can use 5-10%. Complex shapes, stairs, or projects with many cuts should use 15-20%.
Where can I buy bags of concrete mix?
Concrete bags are available at Home Depot, Lowe's, Menards, Ace Hardware, and most building supply stores. Prices typically range from $4-8 per bag depending on size and brand.
How heavy is a bag of concrete mix?
Pre-mixed concrete bags come in 40 lb, 60 lb, and 80 lb sizes. An 80 lb bag makes about 0.6 cubic feet of concrete. Consider your ability to lift and carry when choosing bag size.