# Every yard, bag and bar. Counted.

> Slabs, pads, footings and concrete steps: type the size and StudSheet works out the concrete in cubic yards or bags, the gravel base, the rebar or mesh and the forms, with the math shown and the frost depth for the job’s state or province.

## The concrete Sheets

- **[Concrete slab or footings](https://studsheet.com/sheets/concrete)**: a patio slab, a shed or garage pad, or footings, in ready-mix yards or in bags (80 or 60 lb in the US, 30 kg in Canada), with the gravel base, rebar or mesh, the forms and the control joints.
- **[Concrete steps](https://studsheet.com/sheets/concretesteps)**: the risers and treads to the stair code, the stoop, the concrete, rebar, forms and base, with brick or stone facing if you want it, and the frost and handrail rules where you build.
- **Pavers and block walls**: the [paver patio](https://studsheet.com/sheets/pavers) and [retaining wall](https://studsheet.com/sheets/retaining) Sheets, on the [hardscape page](https://studsheet.com/trades/landscaping).

## From the concrete Sheet: 10′ × 10′ slab, 4″ thick

10′ × 10′ slab, 4″ thick: 1.23 cu yd of concrete; order 1.5 cu yd, plus the gravel base, mesh and forms.

| Buy | Item | How StudSheet counts it |
|---|---|---|
| **1.5 cu yd** | Ready-mix concrete (delivered) | 10′ × 10′ × 4″ = 33.33 cu ft (1.23 cu yd), +10% for an uneven base and spills, rounded up to the next quarter yard. Small loads carry a short-load fee at most plants — ask when you order. |
| **1.5 cu yd delivered** | Crushed stone base, bulk | 100 sq ft × 4″ deep, +20% because gravel compacts = 40 cu ft loose (80 bags — order it in bulk). |
| **3 sheets** | Welded wire mesh, 5×10 ft sheet | Covers 9′ 8″ × 9′ 8″ (2″ in from the edges); sheets lap one full square plus 2″, +10% for cut-offs. |
| **16 chairs** | Rebar chairs or dobies | About one every 3 ft each way, so the mesh ends up at mid-depth instead of lying on the gravel. |
| **1 roll** | Rebar tie wire | Ties the sheet laps together. |

The Sheet has 10 lines like these, each with its math. Change a size and every line follows; on a job, each line takes your price. [The whole worked example](https://studsheet.com/sheets/concrete) · [Open the concrete calculator](https://app.studsheet.com/p/concrete)

## Questions

### How many 80 lb bags of concrete are in a cubic yard?

An 80 lb bag makes about 0.6 cubic feet, so a cubic yard (27 cubic feet) takes about 45 bags. In Canada a 30 kg bag makes about 0.014 m³, about 72 bags to the cubic meter. Past a yard or two, ready-mix by the truck is usually easier; the concrete Sheet shows the job both ways.

### How do you figure cubic yards for a slab?

Length × width × thickness, all in feet, divided by 27. A 10′ × 10′ slab 4″ thick is 100 × 0.333 ÷ 27 = 1.23 cubic yards. Order some extra for spills and an uneven base: the Sheet adds 10% and rounds up to the next quarter yard, 1.5. Open the [concrete calculator](https://studsheet.com/sheets/concrete) for yours.

### Does it check the frost depth?

Footings and steps go below the frost line, which each town sets. The Sheet uses the depth for the job’s state or province and says where it comes from; the [code reference](https://studsheet.com/codes) lists the figures. Confirm with your building department.