Concrete Calculators
ConcreteLab guides
Plain-language answers to concrete calculators questions, written from the same sourced data behind ConcreteLab. Every guide lists its sources and the date it was last updated.
Updated June 10, 2026
How much area does a yard of concrete cover?
One cubic yard is 27 cubic feet, so coverage is 324 ÷ thickness in inches: 81 sq ft at a 4-inch depth, 64.8 sq ft at 5 inches, and 54 sq ft at 6 inches.
Updated June 10, 2026
How many bags of concrete do I need for a slab?
Engine-checked bag counts for common slab sizes: a 10 × 10 ft slab at 4 inches needs about 62 80-lb bags once the standard 10% waste factor is added.