Enter the stair width, rise, run, and step count to calculate concrete volume and cost.
How to Use the Concrete Steps Calculator
Set the stair's width, the rise and run of a single step, and how many steps there are — all four drive the volume, so getting the step count right matters as much as the dimensions.
Picture a staircase from the side: each step is really a slab stacked on the one below it, one riser taller and one tread shorter than the step beneath. Add up all those stacked slabs and you get an arithmetic series — the bottom step contributes one "unit" of height, the next contributes two, and so on up to the top:
cubic feet = width (ft) × run (ft) × rise (ft) × [n × (n + 1) ÷ 2] × (1 + waste %)That n(n+1)/2 term is just the sum of 1 through n — standard stepped-prism geometry, not a rule of thumb. What is an assumption is that the steps are solid concrete all the way to grade. Small stoops usually are poured solid, and this calculator assumes that. Bigger staircases are frequently built over a compacted gravel or block core specifically to avoid pouring that much concrete — if yours is, subtract the core's volume from the result yourself.