Concrete & Masonry Calculator
Concrete, brick, paver, rebar, post-hole and CMU block calculators - in cubic yards, bag counts, weight and piece counts.
The concrete and masonry calculators cover every common pour, wall, patio and stair job: poured concrete slabs and footings, post-hole bag math (with post displacement), CMU block walls, clay brick walls and chimneys, paver patios with base gravel and joint sand, rebar grid takeoffs by spacing and bar size, and poured concrete stairs by step count. Each tool returns the unit you actually buy in - cubic yards for ready-mix, individual bags for retail bagged concrete, brick/paver piece counts and linear feet of rebar. Standard waste (10% for concrete, 5-15% for brick and pavers depending on pattern) is built in so you do not run short halfway through a pour or lay.
Frequently asked questions
A 10 ft x 10 ft slab at 4 inches deep is 33.3 cubic feet (1.23 cubic yards). That is 56 bags of 60lb concrete or 42 bags of 80lb concrete with 10% waste. Above 1 cubic yard, ready-mix delivery is usually cheaper than buying bags. Use the rebar calculator alongside it - a 10x10 slab needs about 16 bars of #4 rebar at 16 inch on-center spacing.
Modular brick with a 3/8 inch joint: 6.86 bricks per sq ft. Standard brick: 6.55 per sq ft. Queen brick: 4.61 per sq ft. King brick: 4.82 per sq ft. A 20x6 ft brick wall needs about 825 bricks plus 10% waste. Mortar runs about 7 bags of 70lb mix per 1000 bricks.
A 12x10 patio is 120 sq ft. With 6x9 inch pavers in a running bond pattern: 320 pavers exact, 336 with 5% waste. Herringbone pattern: 540 pavers exact, 621 with 15% waste. Base gravel: 1.5 cubic yards at 4 inches deep. Bedding sand: 0.4 tons. Plus 2 bags of polymeric joint sand.
A standard 4x4 post hole (10 in diameter, 24 in deep) needs about 1.1 cubic feet of concrete - roughly 2 bags of 60lb or 1.5 bags of 80lb per post. Use the post hole concrete calculator for exact bag counts that account for post size displacement.
#4 rebar (1/2 inch diameter) on a 16 inch grid is the standard for residential slabs, patios and walkways. Step up to #5 (5/8 inch) on a 12-16 inch grid for driveways carrying vehicle weight. The rebar calculator gives you linear feet, bar count, weight and tie wire for any slab size.
All concrete & masonry tools
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