Concrete Stair Calculator
Calculate concrete volume in cubic yards, number of 80-lb bags, rebar count, and form board linear feet for poured concrete stairs. Free with cost estimates.
Concrete Volume
Materials
Cost Estimate
How It Works
Enter the total rise (floor-to-floor height), run per step, and stair width. The calculator automatically determines the number of steps based on a target rise of ~7.5" per step, or you can override it.
Concrete volume is calculated by summing the volume of each step. Each successive step includes the concrete for all rises below it, so the bottom step is the thinnest and the top step is the thickest.
80-lb bags each yield approximately 0.6 cubic feet of mixed concrete. For large jobs, ready-mix delivery at ~$150/cubic yard is more practical.
Form boards include lumber for both sides of the staircase plus riser boards across the front of each step.
Frequently Asked Questions
How many bags of concrete do I need for stairs?
It depends on the number and size of steps. An 80-lb bag of concrete yields about 0.6 cubic feet. This calculator computes the total volume of your staircase and divides by 0.6 to give you the exact bag count. For more than 1 cubic yard, ready-mix delivery is usually more cost-effective.
Do I need rebar in concrete stairs?
Yes. Rebar reinforcement is strongly recommended for structural concrete stairs. A common approach is 2 horizontal rebar pieces per step running the full width, plus vertical rebar ties connecting each step to the one below. This prevents cracking and separation.
How thick should concrete steps be?
Residential concrete steps should be at least 4 inches thick at the thinnest point (typically the nose of each tread). The steps naturally get thicker toward the back because each step sits on top of the accumulated rises below it.
Should I use ready-mix or bagged concrete for stairs?
For small stoops (1-3 steps), bagged concrete is fine. For anything larger, ready-mix is faster and usually cheaper. The break-even is typically around 1 cubic yard — about 45 bags of 80-lb mix. Ready-mix also gives you more working time before it sets.