By Zencalcy Editorial TeamLast reviewed About us
Cast concrete stairs are a stack of rectangular steps plus a solid base, not a hollow staircase. Each step is a box of width × tread × riser, and the total is the sum of those boxes — close enough for ordering, with an allowance for the footing.
Concrete volume for a flight of cast stairs.
V = steps × width × tread × riser
This is the solid volume above the sloped base. Real stairs often have a compacted fill or a slab underneath; if the stairs are cast solid to the ground, add the triangular base volume separately (½ × total rise × total run × width).
| Symbol | Meaning |
|---|---|
| N | Number of steps. |
| w | Stair width. |
| t, r | Tread depth and riser height. |
4 × 4 × 0.917 × 0.583 = 8.56 cu ft; with 10% waste that is 9.4 cu ft, so about 16 bags of 80 lb.
Continue with the Cement Calculator, Concrete Calculator, Concrete Block Fill Calculator, or the Concrete Column Calculator — or browse more cement & concrete and all construction calculators.
7 inch risers with 11 inch treads is the standard exterior stair. The rule of thumb is riser + tread ≈ 18 inches.
Results use standard construction estimating arithmetic: volumes from measured area and depth, unit weights from published material densities, and code-referenced spans or clearances where the page names a code. Quantities are rounded up to whole saleable units and include the stated waste allowance. These tools are planning aids, not structural design, and do not replace a licensed engineer, a local code check, or a contractor's site measurement.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
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Content updated: September 2026