How the concrete estimate works

Volume is calculated from the slab, footing, or round-column dimensions, converted to cubic yards, and increased by the selected waste allowance. Bag counts use approximate yields of 0.60 ft³ for an 80 lb bag, 0.45 ft³ for a 60 lb bag, and 0.375 ft³ for a 50 lb bag.

Ordering guidance

Ready-mix suppliers often have minimum loads and may sell in quarter-yard increments. Bag yield varies by manufacturer and mix. Confirm the selected product’s stated yield before purchase.

Example

A 10 ft × 10 ft slab at 4 inches thick is about 1.23 yd³ before waste. With 10% added, plan for approximately 1.36 yd³.