Key takeaways
- Each solid step is as deep as all the treads in front of it, so volume climbs quickly with height.
- A top landing often uses more concrete than the steps.
- This gives volume only, so footing and reinforcement questions go to your building department.
Enter the width, number of steps, and each step's rise and tread. Add a top landing if the steps end at a door. The tool assumes solid steps down to the bottom step's base.
How the calculator works
- Steps: width × rise × tread × (steps × (steps + 1) ÷ 2)
- Landing: width × landing depth × total rise
- Yards: total cubic feet ÷ 27
The middle part counts how the steps stack. With three steps, the bottom row holds 3 treads of concrete, the next 2, and the top 1, which makes 6 in all.
Worked example
Three steps, 4 feet wide, with a 7 1/2-inch rise and 11-inch tread, and 5% extra:
- 4 × 7.5 × 11 × 6 ÷ 144 = 13.75 cubic feet
- With extra: 14.4 cubic feet, or about 0.53 cubic yards
- 25 bags of 80 lb
The landing changes everything
Same steps, adding a 36-inch deep landing at the top:
| Part | Cubic feet |
|---|---|
| Three steps | 13.75 |
| 36 in landing, 4 ft wide, 22.5 in high | 22.50 |
| Total | 36.25 |
So the landing is more than the steps themselves. Check the landing requirement before you plan the pour. The 2021 IRC calls for a landing at the top and bottom of each stairway, with exceptions, and these changed in the 2024 edition.
Step sizes
The 2021 International Residential Code's figures for stairs serving a building are a riser of at most 7 3/4 inches and a tread of at least 10 inches. To work out how many steps you need, use the stair calculator. Exterior landscape steps not serving a building, porch or deck can be excepted, so ask your building department.
Before you pour
- Base: ask what footing your steps need. Frost and soil can move steps that aren't supported properly, and the IRC's frost rules are in Section R403.
- Connection: ask how the steps should relate to the house, because a rigid connection can cause trouble if either one moves.
- Reinforcement: this comes from your local rules or an engineer.
- Handrail: the 2021 IRC calls for one on flights with four or more risers.
- Digging: contact 811 a few business days ahead.
Frequently asked questions
How much concrete for 3 steps?
For steps 4 feet wide, with a 7 1/2-inch rise and 11-inch tread, about 13.75 cubic feet before any allowance.
How many bags for concrete steps?
The same 3 steps take 23 bags of 80 lb with no allowance, or 25 with 5% extra. Use the calculator for your size.
Can I reduce the concrete with fill?
Builders sometimes do, but it changes the structure and the calculation. Ask your building department or a contractor.
Sources
We use primary sources where we can: building codes, federal rules and manufacturer documents. Read our editorial standards.
- 2021 International Residential Code, Chapter 3, Section R311.7
- QUIKRETE: Concrete Mix data sheet, product 1101 (bag yields)
- 811: What is 811?