Building calculators
Material quantity calculators that show their working. Concrete, aggregate, sand, topsoil, mulch and asphalt — with the densities, bag yields and code figures shown alongside the answer so you can check it.
Concrete
- Concrete Slab CalculatorEnter the slab dimensions to get cubic yards, bag count by bag size, and an estimated material cost.
- Concrete Driveway CalculatorDriveways carry wheel loads, so they are thicker than a patio. Enter the dimensions for cubic yards, bag count a
- Concrete Footing CalculatorEnter the total run of footing, its width and thickness. Use the runs field if you have several identical footin
- Post Hole Concrete CalculatorEnter the hole size and post dimension. This subtracts the volume the post occupies, which most calculators skip
- Concrete Steps CalculatorEnter the step width, count, rise and tread. This uses the real staircase volume, not one block per step.
- Concrete Wall CalculatorEnter the wall dimensions and the total area of any windows or doors to deduct.
- Concrete Column & Pier CalculatorFor round forms, piers and tube footings. Enter the diameter, the height of the pour and how many you are placin
Aggregate
- Gravel CalculatorEnter the area and depth. You get loose cubic yards, tonnage at a real density, and a cost if you know your yard
- Gravel Driveway CalculatorA gravel driveway is built in lifts, not as one dump of stone. Enter the depth of each layer to get the total to
- Paver Base CalculatorEnter the paver area and your base depth. This sizes the crushed stone only — bedding sand is a different materi
- Sand CalculatorEnter the area and depth for cubic yards, tonnage and a 50 lb bag count.
Landscape
Asphalt
Reference
- Cubic Yard CalculatorThe plain version: dimensions in, cubic yards out. Use this when you know your own material density or your supp
- Concrete Bags Per Cubic YardA cubic yard is 27 cubic feet. Divide that by the bag yield and you have your answer.
- Material Weight ChartBulk materials are sold by weight and measured by volume. These are the densities that get you between the two.
Why the working is shown
Every calculator in this section prints its intermediate volume, the allowances applied, and the density or bag yield used to get from volume to what you actually buy. That is deliberate. A material estimate you cannot check is a material estimate you cannot trust, and the errors are not always small — the two most common ones in this category are quietly severe.
The first is treating poured steps as one block per step. A solid stair is a triangular number of the rise, so a five-step flight needs three times the concrete that the simple version reports. The second is converting volume to tons by relabelling cubic yards, which understates a gravel order by about 35% because crushed stone weighs roughly 1.35 tons per cubic yard, not one.
The volume maths here is a single shared module with a test suite that checks every shape against hand-computed references, including both of those cases. Densities and yields are listed on the material weight chart and the bags per cubic yard page.
What these estimates do not cover
Quantities only. Footing depth depends on your frost line, retaining walls over four feet need engineering, slab reinforcement depends on load, and all three are set locally. Where a code figure is relevant it is cited on the page, but your building department has the number that counts.