How Much Concrete for a 10×10 Slab?

Project Assumptions

This concrete example uses a simple slab footprint and common bag yield estimates. Concrete products vary, so always check the bag label.

• Slab size: 10 ft x 10 ft
• Thickness: 4 inches
• Area: 100 square feet
• Approximate 80 lb bag yield: 0.6 cu ft
• Approximate 60 lb bag yield: 0.45 cu ft
• Extra material allowance: 10%

Step-by-step Calculation

Area = 10 x 10 = 100 sq ft. Thickness in feet = 4 / 12 = 0.333 ft.

Cubic feet = 100 x 0.333 = 33.3 cu ft. Cubic yards = 33.3 / 27 = 1.23 cu yd.

Eighty-pound bags = 33.3 / 0.6 = 55.5, so round up to 56 bags. Sixty-pound bags = 33.3 / 0.45 = 74, so round up to 75 bags.

With 10% extra, concrete volume = 36.7 cu ft. That is about 62 bags of 80 lb mix or 82 bags of 60 lb mix.

Practical Buying Notes

Concrete bag yield varies by brand, mix type, and water ratio. Always check the label on the bag before purchasing.

For larger slabs, ready-mix delivery may be more practical than mixing dozens of bags by hand.

Common Mistakes

Concrete projects are harder to pause once the pour begins, so planning extra material matters.

• Forgetting to convert 4 inches into feet.
• Not checking bag yield.
• Underestimating waste and uneven base conditions.
• Forgetting formwork dimensions.
• Starting a pour without enough material on site.