Concrete & Masonry Calculators
Concrete is sold by volume: cubic yards = length × width × thickness (in) ÷ 12 ÷ 27. A 10 × 10 ft slab 4 in thick is 1.23 cu yd, about 56 bags of 80 lb mix. Masonry units are counted by face area instead, using the tools below.
Concrete Calculator
Cubic yards and 80/60/40 lb bags for slabs, pads and footings.
Concrete Block Calculator
Number of 8×8×16 CMU blocks for a wall.
Brick Calculator
Bricks per wall from brick size and mortar joint.
Paver Calculator
Pavers, gravel base and bedding sand for a patio.
Post Hole Concrete Calculator
Bags of concrete for fence and deck post holes.
Volume versus unit counts
Poured work is measured in cubic feet or cubic yards; masonry is counted by the number of units that fit a face area. Slabs, pads and footings use length × width × depth, while block, brick and pavers depend on the nominal size of one piece including its joint. For anything structural, such as foundations or load-bearing walls, use these figures for budgeting and let your plans and inspector set the final specification.
Which calculator do I need?
- Concrete: patios, sidewalks, shed pads and rectangular footings, in cubic yards or 40/60/80 lb bags.
- Concrete block: CMU walls and foundations built from 8 × 8 × 16 units.
- Brick: veneer, garden walls and fireplace surrounds using modular, queen or king sizes.
- Paver: patios and walkways, including the gravel base and bedding sand.
- Post hole concrete: setting fence, mailbox or deck posts and sono tube piers.
Before you buy
Pick a dry, mild day for pours and mortar work, and avoid freezing temperatures for the first several days of curing. Have helpers, a wheelbarrow and finishing tools ready before the first bag is opened or the truck arrives. Stack block and brick near the work to limit handling. Cutting masonry releases silica dust, so wet-cut or use a saw with a vacuum and wear a respirator.
Frequently asked questions
How many 80 lb bags are in a yard of concrete?
About 45, because each bag yields roughly 0.6 cu ft and a yard is 27 cu ft.
When should I order ready-mix instead of bags?
Above about one cubic yard, a truck is usually cheaper and easier.
Do I need rebar?
Many slabs, footings and block walls need reinforcement; follow local code and your plans.
How many pavers per square foot?
For 4 × 8 in pavers, 4.5 per square foot.