Concrete Stairs Calculator
This concrete step calculator estimates the concrete for a flight of stairs. As a concrete stair calculator it adds up the stacked step prisms — plus an optional landing — from the number of steps, the rise, the run, and the width. The result gives you cubic yards, cubic feet, and bag counts for porch steps, stoops, and entry stairs.
How to use this calculator
- Enter the number of steps and the stair width.
- Enter the rise (step height) and run (step depth).
- Add a landing depth only if there is a platform at the top.
- Read the total cubic yards or bag count, including a waste allowance.
The formula
Stairs are a stack of prisms that grow toward the bottom. The side cross-section area equals run × rise × n(n + 1) ÷ 2 for n steps; multiply by the width for the volume:
Cubic feet = Width ft × Run ft × Rise ft × n(n + 1) ÷ 2
Worked example. Three steps, 7 inch rise, 11 inch run, 3 ft wide: rise 0.583 ft, run 0.917 ft, and 3(3 + 1) ÷ 2 = 6. So 3 × 0.917 × 0.583 × 6 = 9.6 cubic feet, about 0.36 cubic yards or 16 × 80 lb bags.
Frequently asked questions
How do I calculate concrete for stairs?
Each step is a stacked prism, so the side profile area equals run × rise × n(n+1)/2 for n steps. Multiply that by the stair width to get the volume. This calculator handles the math for you.
How much concrete do I need for 3 steps?
Three steps with a 7 inch rise, 11 inch run, and 3 foot width come to about 9.6 cubic feet (0.36 cubic yards) — roughly 16 × 80 lb bags.
What are standard stair rise and run dimensions?
A comfortable stair has a 7 inch rise and an 11 inch run. Most codes cap the rise at about 7¾ inches and require at least a 10 inch run.
Should I include a landing in the estimate?
Yes. Add the landing or platform depth so its slab is included at the full stair height. This calculator has an optional platform depth field for exactly that.