Concrete & Masonry Calculators
Work out exactly how much concrete, block, brick and reinforcement a job needs — in cubic yards, cubic metres or bags. Every calculator shows the volume, the bag count and an optional cost, with a waste allowance built in.
Choose a calculator
Concrete Calculator
Free concrete calculator: enter your slab dimensions and get cubic yards, cubic metres, bags needed and estimated cost.
Concrete Slab Calculator
Free concrete slab calculator for patios, driveways, garage floors and shed bases.
Brick Calculator
Free brick calculator: work out how many bricks and how much mortar a wall needs.
Concrete Footing Calculator
Free footing calculator: enter footing length, width and depth to get concrete volume in cubic yards, bags needed and cost.
Post Hole Concrete Calculator
Free post hole concrete calculator: work out bags of concrete per post and in total for fence posts, deck posts and mailboxes.
Concrete Block Calculator
Free concrete block calculator: work out how many CMU blocks and how much mortar a wall needs from its length and height.
Rebar Calculator
Free rebar calculator for slabs: work out how many bars, total linear feet and the number of tie intersections from your slab size, spacing and lap length.
Why ordering concrete short is expensive
Concrete is the one material where running out mid-pour is a genuine problem. A cold joint forms where fresh concrete meets partly set concrete, and it becomes a permanent weak line through the slab. Short loads also carry a surcharge from most ready-mix suppliers, and a second truck for half a yard can cost more than the concrete itself. That is why every calculator here adds a waste allowance by default: over-ordering slightly is far cheaper than the alternative.
Bags versus ready-mix
A 80 lb bag yields about 0.6 cubic feet, so a cubic yard takes roughly 45 bags. Mixing that by hand is a long day's work. As a rough guide, under half a cubic yard is comfortable with bags, half to one yard is hard but possible, and beyond one cubic yard ready-mix is almost always cheaper once you count your own time. Our calculators show both figures so you can judge for yourself.
Frequently asked questions
How much concrete do I need?
Multiply length × width × thickness to get cubic feet, then divide by 27 for cubic yards. Enter your dimensions above and the calculator does it, including a waste allowance.
How many bags of concrete are in a cubic yard?
About 45 of the 80 lb bags, 60 of the 60 lb bags or 90 of the 40 lb bags. A cubic yard is 27 cubic feet and an 80 lb bag yields roughly 0.6 cubic feet.
How much extra concrete should I order?
Between 5% and 10% for most jobs. Uneven subgrade, over-excavation and spillage all consume more than the theoretical volume.
Are these calculators free?
Yes — no account, no limits, and nothing you enter leaves your browser.
Do they work in metric?
Yes. Every dimension has its own unit selector, and results are given in cubic yards, cubic feet and cubic metres.