Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Calculate concrete volume for a solid set of steps using the stacked-block stair formula.
Assumes solid, closed-riser steps with no separate landing. Open-riser stairs need less concrete than this estimate.
Solid concrete steps aren't a simple rectangular pour -- each step supports the ones above it, so the shape is a stack of decreasing rectangular blocks rather than one uniform slab. This calculator uses the standard construction-industry method for estimating that volume from four numbers: how many steps, the rise (height) and tread (depth) of each step, and the width of the staircase.
Picture the staircase from the side. The bottom step is really a block that spans the entire horizontal run of the staircase and is one rise tall. The step above it spans everything except the bottom step's tread, and is also one rise tall. Each step up removes one tread's width from the block beneath it -- so summing every step's block gives a stair-stepped total, not a flat rectangle.
Volume (cu ft) = Width (ft) × Rise (in÷12) × Tread (in÷12) × n(n+1)/2
n = number of steps
The n(n+1)/2 term is the sum 1+2+3+...+n -- exactly the "stacked blocks" pattern described above, where step 1 (the top) contributes one tread-width of block, step 2 contributes two, and so on down to the bottom step contributing n tread-widths.
This is the calculator for a small poured-concrete stoop or set of porch/patio steps -- typically 2 to 6 steps. For a larger exterior stair with a structural stringer and separate tread material, see the Stair Calculator and Stair Stringer Calculator instead, which handle framed (not solid-poured) stairs.
This formula assumes solid, closed-riser steps with no separate landing pad and a uniform rise and tread on every step. Open-riser stairs (with a gap under each tread) use noticeably less concrete than this estimate, and a landing at the top or bottom adds volume this formula doesn't include -- calculate a landing as a separate rectangular slab and add it in.
Consider a four-step entry with a 7 in rise, 11 in tread and 3 ft width. The stacking term is 4 × 5 ÷ 2 = 10. The raw volume is 3 × 0.583 × 0.917 × 10, which is about 16.04 cubic feet. With a 10 percent allowance that becomes roughly 17.65 cubic feet, or about 0.65 cubic yards. That is a small quantity, so bagged mix may be more practical than a truck, and you would compare the bag count against a delivery minimum.
3 × (7 ÷ 12) × (11 ÷ 12) × 10 = 16.04 cu ft
The stacked-block method assumes each step is solid all the way down to the ground. If the steps sit on a slab or compacted base with a hollow core, less concrete is needed. If the ground slopes away, the bottom step may need to be deeper, which adds concrete beyond the formula. Steps may also need footings below frost depth in cold climates, and those footings are a separate calculation.
Building codes govern maximum rise, minimum tread and handrail requirements, and they differ by location. Check your local requirements before you build, and consult a qualified contractor if the steps are attached to a structure or are more than a few steps high. This tool estimates volume only and does not check code compliance.
A 7-inch rise and 11-inch tread is a common comfortable ratio for exterior steps, though local building codes set the actual allowable range and may require it to match your specific stair run exactly.
Because each lower step has to physically support the full horizontal run of every step above it -- the bottom step is much larger than the top step, not identical to it, which is why the calculation uses a sum rather than a simple multiplication.
No -- calculate a landing as its own rectangular slab (length x width x thickness, like the Concrete Calculator) and add that volume to the stair volume separately.
Yes -- this formula assumes solid, closed-riser construction. Steps with an open back (no riser face, or a hollow riser) use less material than this estimate.
Calculate it as its own slab from length, width and thickness, then add that volume to the stair volume before ordering.
Volume scales directly with width, so doubling the width doubles the concrete needed.
The formula assumes equal rise and tread. For uneven steps, calculate each step block separately and add them, though ideally the steps should be made uniform.