Concrete Steps Calculator
Calculate the volume of concrete needed for a flight of stairs — including the optional top platform — then estimate bags and total cost.
Stairs dimensions
Risers from ground up to landing.
Standard residential width is 36–48 in (90–120 cm).
Leave blank to use the same width as the stairs.
Only the slab portion above the top step is counted.
Recommended 5–10% extra for spillage and over-pour.
Bag size selected above will be used.
How is this calculated?
Each step is treated as a rectangular block. Counted from the top, step 1 has 1 riser of height under it, step 2 has 2, and so on. So the total step volume is:
width × tread × riser × N × (N + 1) ÷ 2
where N is the number of steps. If you include a top landing, its slab volume (depth × width × thickness) is added.
A waste allowance (10% by default) is then added so you order enough.
Bag estimates use standard yields: 40 lb ≈ 0.30 ft³, 60 lb ≈ 0.45 ft³, 80 lb ≈ 0.60 ft³.
Tip: For safe stairs, follow your local building code — common rules of thumb are riser 6"–7¾" (15–20 cm) and tread 10"–11" (25–28 cm).