Concrete Stairs Calculator
Concrete steps are one of the trickier pours to estimate because the staircase shape is not a simple rectangle. This calculator uses the correct triangular prism formula for each step to give you an accurate cubic yard count — no over-ordering, no running short mid-pour.
How to use this calculator
- Enter the number of steps and the step width in feet.
- Set the rise (height per step) and run (depth per step) in inches.
- Adjust the waste factor — steps often need 15–20% extra.
- Read your cubic yards — most residential steps fall under 1 yd³ and suit bagged mix.
How we calculate this
Each step is modelled as a triangular prism: volume = ½ × rise × run × width. For a full staircase, the total volume = (number of steps + 1) × ½ × rise × run × width + the landing slab if present. A 4-step stair, 4 ft wide, 7-inch rise, 11-inch run gives (4+1) × 0.5 × (7/12) × (11/12) × 4 = 5.35 cu ft per tread stack = 1.07 cu ft × 5 = about 1.07 cubic yards total including landing.
What this calculator doesn't include
This calculator assumes solid poured-in-place concrete steps with no void fill (gravel or block fill). Hollow-core steps with fill significantly reduce concrete volume — deduct the void volume manually. The calculator does not include the landing pad at the top or bottom unless entered as additional thickness. Rebar, forms, and broom finish labour are not included.
Example concrete estimates — Concrete Stairs
Pre-calculated for common project sizes. Includes 10% waste factor.
| Configuration | Cubic Yards | With Waste | 80 lb Bags |
|---|---|---|---|
| 3 steps, 4 ft wide, 7" rise, 11" run | 0.475 yd³ | 0.52 yd³ | 24 |
| 3 steps, 5 ft wide, 7" rise, 11" run | 0.594 yd³ | 0.65 yd³ | 30 |
| 4 steps, 4 ft wide, 7" rise, 11" run | 0.792 yd³ | 0.87 yd³ | 40 |
| 4 steps, 5 ft wide, 7" rise, 11" run | 0.99 yd³ | 1.09 yd³ | 50 |
| 5 steps, 4 ft wide, 7" rise, 11" run | 1.188 yd³ | 1.31 yd³ | 59 |
| 5 steps, 5 ft wide, 7" rise, 11" run | 1.485 yd³ | 1.63 yd³ | 74 |
| 6 steps, 4 ft wide, 7" rise, 11" run | 1.664 yd³ | 1.83 yd³ | 83 |
| 6 steps, 5 ft wide, 7" rise, 11" run | 2.079 yd³ | 2.29 yd³ | 103 |
All estimates include a 10% waste factor. Under 1 yd³ is typically practical with bagged mix; over 1 yd³ usually warrants a ready-mix truck.
Frequently asked questions
The most comfortable outdoor step has a 7-inch rise and 11-inch run (tread depth), which follows the classic stair formula: 2 × rise + run = 25 inches. For residential exterior steps, codes typically allow rise between 4–7.75 inches and run (tread) of at least 11 inches. A 7-inch rise and 11-inch run is the industry default and the most widely approved combination.
A 3-step stoop, 4 feet wide, 7-inch rise, 11-inch run is approximately 0.64 cubic yards (17.3 cubic feet). With 10% waste that is 19 cubic feet — about 32 bags of 80 lb mix. This is on the edge between bag and ready-mix — a mini-load from a ready-mix supplier may cost less than 32 bags plus your time mixing them.
Solid poured steps are the most durable but use the most concrete. Large stoops are often built over a gravel or block fill base to reduce the volume of concrete needed — the steps are then poured as a shell over the fill. For small stoops (3–5 steps), solid is usually simpler and more cost-effective.
The landing slab under and around steps should be at least 4 inches thick. If the steps bear on a footing (recommended in freeze-thaw climates), the footing should extend below the frost line to prevent heave. Steps that are not on a proper footing may crack or shift with freeze-thaw cycles.
Use 4,000 PSI air-entrained concrete in freeze-thaw climates. Place rebar (at minimum one horizontal bar per step). Ensure adequate subgrade compaction. Use control joints at the stoop-to-slab connection to allow movement. Cure the concrete properly with curing compound or wet burlap for at least 7 days. Avoid pouring in temperatures below 40°F or above 90°F without special precautions.