Concrete Steps Calculator

A concrete steps calculator returns the volume of a solid poured staircase as cubic yards, a ready-mix order size, and a bag count. It multiplies width, run and rise by N(N+1)/2 for N steps, since each lower step spans more of the run. It then adds an 8% waste allowance by default.

Last reviewed September 2026Method & sources Report an error

Not to scale.

Concrete Needed (with waste)

0.51 cu yd

Includes a 8% waste allowance.

Shopping list

Concrete mix24 80 lb bagsRounded up from 23.1 bagsOr 0.75 cu yd of ready-mix delivered.
Bagged

Bagged vs. Ready-Mix

Under 1 cubic yard: bagged concrete is usually practical for a small set of steps - no delivery minimum, and the stepped formwork means you can place concrete in manageable sections anyway.

Breakdown
Concrete Needed (with waste)	0.51 cu yd
Total Volume (with waste)	13.9 cu ft
Bags Needed	24 bags (80 lb)
Ready-Mix Order Size	0.75 cu yd
Estimated Cost (Bags)
Estimated Cost (Ready-Mix)

How to Calculate Concrete Steps

Solid poured concrete steps stack like a set of rectangular boxes viewed from the side. The bottom step is a box spanning the full staircase run and one riser tall. The next step's box is one tread shorter and sits on top of it, and so on up to the top step. Summing those box areas works out to Run × Rise × (1 + 2 + ... + N). That is the triangular number N(N+1)/2, so total volume is `Width × Run × Rise × N(N+1)/2`, with rise and run converted from inches to feet first. A waste allowance is then applied using the same NRMCA ready-mix ordering guidance (4-10% over the plan-dimension estimate) as the Concrete Slab calculator. It defaults to 8% since stepped formwork typically has more edges and corners than a flat slab. The waste-adjusted volume converts to cubic yards (÷27, rounded up to the nearest quarter yard for a ready-mix order) or to a bag count using the same 40/60/80 lb yield figures.

Example: 3 steps, 7 in. rise, 11 in. run, 4 ft wide, at 8% waste

3 steps, 7 in. rise, 11 in. run, 4 ft wide, at 8% waste, using 80 lb bags: 1. Rise in feet: 7 ÷ 12 = 0.583 ft. Run in feet: 11 ÷ 12 = 0.917 ft 2. Triangular number for 3 steps: (3 × 4) ÷ 2 = 6 3. Raw volume: 4 × 0.917 × 0.583 × 6 ≈ 12.83 cubic feet 4. With 8% waste: 12.83 × 1.08 ≈ 13.86 cubic feet 5. Cubic yards: 13.86 ÷ 27 ≈ 0.51 cubic yards 6. Ready-mix order size, rounded up to the nearest ¼ yard: 0.75 cubic yards 7. Bags (80 lb, 0.60 cu ft each): 13.86 ÷ 0.60 ≈ 23.1, rounded up to 24 bags At about half a cubic yard, bagged concrete is the practical choice for this staircase. 24 bags is a manageable single-session pour.

Concrete Steps: Compare Scenarios

Scenario	Concrete Needed (with waste)	Total Volume (with waste)	Bags Needed	Ready-Mix Order Size
Small (3 steps, standard width)	0.51 cu yd	13.9 cu ft	24 bags (80 lb)	0.75 cu yd
Medium (6 steps, 4 ft wide)	1.80 cu yd	48.5 cu ft	81 bags (80 lb)	2.00 cu yd
Large (10 steps, 6 ft wide porch stair)	7.06 cu yd	190.6 cu ft	318 bags (80 lb)	7.25 cu yd

What Is Concrete Steps?

A concrete steps calculator converts a staircase's dimensions (number of steps, rise, run, and width) into the volume of concrete needed to pour it solid. It then expresses that as either a ready-mix order or a bag count. It exists because a staircase isn't a simple box. Each step adds a decreasing amount of material as the stairs go up, so an accurate volume needs the stacked-step geometry, not just a footprint multiplied by height.

Concrete Steps: Pros and Cons

Pros

Uses the correct stacked-step (triangular number) geometry instead of treating the staircase as one flat slab, which would significantly overestimate volume
Applies the same NRMCA-based waste guidance used across this site's other concrete calculators, with a higher default to reflect stepped formwork
Shows both the bagged-mix and ready-mix path so labor and delivery minimums can be weighed against cost

Cons

Assumes solid steps poured on a stable, compacted base. It doesn't include a separate footing or slab pad underneath, which many staircases need for frost protection or structural support
Assumes uniform rise, run, and width for every step. A staircase with a landing, a curve, or varying step sizes needs each section calculated separately and added together
Does not size reinforcement (rebar). Most poured concrete steps are reinforced per local code, which this calculator does not determine

Concrete Steps: What a Pro Checks

Plan for one continuous pour across the whole staircase if you can. The stacked-step geometry means the bottom step alone often needs more concrete than a whole flat slab of the same footprint. A cold joint between steps is a visible weak point.
Check whether your steps need rebar before you pour. Most poured concrete steps are reinforced per local code, commonly tied into the footing below, and this calculator only covers the concrete volume.
Add a footing or pad under the staircase separately. This calculator computes only the solid stepped volume, not any frost-depth footing or slab base most outdoor staircases also need.

Frequently Asked Questions

How do you calculate concrete for steps?

Steps stack like boxes of decreasing length, so total volume is Width × Run × Rise × N(N+1)/2. Here N is the number of steps, and N(N+1)/2 is the sum 1 + 2 + ... + N. This accounts for the bottom step needing much more material than the top step, unlike a flat slab of the same footprint.

Does this include the footing or slab under the steps?

No. This calculates only the solid volume of the stepped staircase itself. Many outdoor staircases need a footing below the frost line or a concrete pad underneath for support. Calculate that separately with the Concrete Footing or Concrete Slab calculator and add it to this result.

What rise and run should I use for outdoor steps?

This varies by local building code and by what feels comfortable to walk. Typical residential exterior steps run roughly 6-7 in. of rise and 11-12 in. of run. Check your jurisdiction's specific requirements before finalizing a design, since many codes set minimum and maximum values and require consistency between steps.

Do concrete steps need rebar?

Most poured concrete steps are reinforced, commonly with rebar tied into the footing below, per local code requirements that vary by jurisdiction and step size. This calculator only covers the concrete volume. Once your reinforcement plan specifies bar size and spacing, use the Rebar Material calculator for that quantity.

Why is the waste allowance higher for steps than for a flat slab?

This calculator defaults to 8% for steps versus 5% for a flat slab, since stepped formwork has more corners, edges, and form transitions where spillage and minor overfill are more likely. Use a higher percentage still if your design has an unusual step shape or a lot of formwork bracing.

Can I use this for steps with a landing?

Not directly. This calculator assumes a simple straight run of uniform steps. For a staircase with a landing, calculate the straight-run sections with this calculator and the landing as a flat slab with the Concrete Slab calculator, then add the volumes together.

Sources

Concrete & Masonry