Tools you might need next
Calculate rebar quantity and spacing for concrete slabs. Enter slab size, bar spacing, and stock length to get bar count, linear feet, and sticks to buy.
Estimate mortar for block and brick walls. Enter wall area and joint thickness for mortar volume in cubic feet, premix bags, and site-mix batch counts.
Calculate CMU blocks needed for walls. Enter wall length, height, and block size to get block count with 5% waste for masonry and construction projects.
Convert slab thickness from inches to feet by dividing by 12, then multiply length, width, and depth for total volume in cubic feet.
Volume (cu ft) = Length (ft) × Width (ft) × Depth (in) ÷ 12Ready-mix concrete is ordered in cubic yards in the US. One cubic yard equals 27 cubic feet.
Cubic Yards = Cubic Feet ÷ 27Add 10% for spillage, uneven subgrade, and form overfill. Round up to the nearest quarter yard when ordering from a batch plant.
Order (cu yd) = Net Volume (cu yd) × 1.10Updated: July 2026
A homeowner pouring a 24×20 ft garage pad at 4″ thickness needs about 5.9 cu yd net (6.5 cu yd with 10% waste). Order 7 yards to avoid a short load fee.
A 40 ft × 4 ft sidewalk at 4″ deep requires roughly 2.0 cu yd. Use the calculator to confirm before scheduling a Saturday pour with neighbors.
Twelve fence post holes 12″ diameter × 36″ deep total about 0.35 cu yd. Bagged mix (≈45 bags) may be cheaper than a minimum ready-mix load for small pours.
Estimate how much ready-mix concrete or bagged mix you need for slabs, pads, and footings before ordering from the plant. Enter room or pour dimensions in feet and thickness in inches to get cubic yards, cubic feet, and approximate 80 lb bag counts with a standard waste allowance.