Concrete Steps & Stairs Calculator: Yards, Bags & Cost
This concrete steps and stairs calculator estimates the volume of poured stairs from your run, rise, width and number of steps, accounting for the stepped stacking of each tread. Stairs are deceptively concrete-heavy, so an accurate estimate keeps you from under-ordering on a pour you can't pause.
Estimated concrete
Estimates only. Add ~5–10% for waste. Bag yields: 40 lb ≈ 0.30, 60 lb ≈ 0.45, 80 lb ≈ 0.60 cu ft. Concrete ≈ 150 lb per cu ft.
How the Concrete Steps & Stairs Calculator works
- 1
Enter your dimensions
Type the length, width and thickness of your slab, footing or pad and choose your units, feet, inches or meters.
- 2
Get instant volume
See the result in cubic yards, cubic feet and cubic meters, plus weight, the moment you type, no page reloads.
- 3
Buy the right amount
We convert volume into the exact number of 40, 60 and 80 lb bags, truck loads and cost so you order without waste or shortfalls.
The formula
ft3 = width_ft x run_ft x (sum of step rises_in / 12) + platform volume
- ·width_ft = step width (feet)
- ·run_ft = tread depth of each step (feet)
- ·rise_in = height of each riser (inches)
- ·platform = width x depth x thickness of any top landing
- ·27 = cubic feet per cubic yard
Solid steps are modeled as stacked boxes: each step reaches grade, so lower steps carry the full height of the steps above. A default 10% waste is added.
Worked examples
Example 1: 3-step stoop, 4 ft wide, 11 in run, 7 in rise, no platform
- Step heights to grade: 7 in, 14 in, 21 in (sum = 42 in)
- Volume = 4 x (11 / 12) x (42 / 12) = 4 x 0.917 x 3.5
- = 12.83 ft3, then / 27 = 0.48 yd3
Result: about 12.8 ft3 (0.48 cubic yards)
Example 2: 2 steps (3 ft wide, 12 in run, 6 in rise) plus a 3x4 ft platform, 6 in thick
- Steps: 3 x 1 x ((6+12) / 12) = 3 x 1 x 1.5 = 4.5 ft3
- Platform: 3 x 4 x (6 / 12) = 6 ft3
- Total = 4.5 + 6 = 10.5 ft3 = 0.39 yd3
Result: 10.5 ft3 (about 0.39 cubic yards)
Concrete calculators by project type
Concrete bag yield & coverage
How much mixed concrete a standard bag yields, and how far a cubic yard goes at common slab depths.
| Bag size | Yield (cu ft) | Bags per cubic yard |
|---|---|---|
| 40 lb | 0.30 | 90 |
| 60 lb | 0.45 | 60 |
| 80 lb | 0.60 | 45 |
- 40 lb
- 60 lb
- 80 lb
Related guides
Concrete steps & stairs calculator FAQs
How do you calculate concrete volume for steps?
Each step is a stacked box, so the total volume is the sum of every tread's run × rise × width, which forms a staircase cross-section times the width. This calculator adds those stepped layers for you rather than treating the stairs as a solid block.
What are standard concrete step dimensions?
A comfortable stair typically uses a 7-inch rise and an 11-inch run, with treads at least 36 inches wide for a walkway. Local code often caps rise around 7.75 inches and sets a minimum run for safety.
How much concrete do I need for a 3-step stoop?
A 3-step stoop about 4 ft wide with 7-inch rises and 11-inch runs typically needs roughly 0.5–0.7 cubic yards, depending on platform depth. Solid poured stoops use more than open-riser forms.
Can I save concrete by filling steps with rubble or foam?
Yes, packing the hollow core of a stair form with compacted fill or foam blocks reduces concrete volume for the interior. Keep a solid concrete shell of several inches on the treads, risers and sides for strength.
Should concrete steps have rebar?
Yes, poured steps should be reinforced with rebar or mesh to resist cracking and to tie the stairs into any adjacent slab or foundation. Reinforcement is especially important on freestanding stoops.
Is ready-mix or bagged concrete better for stairs?
Because stairs must be poured and finished before the concrete sets, ready-mix delivery is usually best for anything over about a yard. Small stoops under a yard can be done with bagged mix if you can place it quickly.
What is a comfortable rise and run for outdoor steps?
Aim for a riser height of 6 to 7.5 inches and a tread run of 11 to 12 inches. A common comfort check is that two risers plus one run should total roughly 25 inches, which keeps the climb even and safe.
How wide should exterior concrete steps be?
Building codes generally require at least 36 inches of width, but 48 inches feels far more comfortable and lets two people pass. Wider steps use proportionally more concrete, so measure before you calculate volume.
How many bags of concrete do I need for a small stoop?
Convert your total cubic feet and divide by the bag yield: 0.60 ft3 for an 80 lb bag. A 12.8 ft3 three-step stoop needs about 22 eighty-lb bags, which is why most people order ready-mix for anything larger.
Do concrete steps need a footing?
Structural steps attached to a building should sit on a footing that extends below the local frost line so they do not heave and separate from the house. Freestanding garden steps on well-drained gravel can often skip a deep footing.
Should step treads be sloped?
Give each tread a slight forward pitch of about 1/8 to 1/4 inch per foot so rain drains off instead of pooling. This reduces ice buildup in winter and keeps the treads from staining.
Can I pour new steps against an existing slab?
Yes. Drill and epoxy short rebar dowels into the existing slab or foundation so the new steps tie in and move together. Without dowels, the joint tends to crack and the steps can pull away over time.
How long before I can use new concrete steps?
You can walk on them carefully after 24 to 48 hours once the forms are stripped, but the concrete keeps gaining strength for 28 days. Avoid heavy loads or deicing salt during that first month.