Concrete Step Calculator
Estimate concrete volume and bags for steps and stoops. Riser and tread notes cite model IRC limits only — not a code approval.
Your estimate
51 bags
80 lb bags (incl. 10% waste)
- Concrete volume (incl. waste)
- 30.16 cu ft (1.12 cu yd)
- Total rise
- 21 in
- Total run (incl. landing)
- 58 in
- Total weight
- 4,080 lb
Other sizes for comparison
- 60 lb bags
- 68
- 40 lb bags
- 101
- This is over ~1 cu yd (0.76 m³) — get a ready-mix quote, or fill the core with compacted gravel to cut the volume.
Show the math
- Steps below the landing: riser × tread × (1 + 2 + … + 2) = riser × tread × 3
- Landing: riser × 3 × landing depth
- Volume = width × riser × (tread × 3 + landing × 3) = 27.42 cu ft
- × (1 + 10%) ÷ bag yield = 50.26 → 51 bags
Shopping list & cost
| Item | Spec | Qty | Cost |
|---|---|---|---|
| Premix concrete | 80 lb bag | 51 bags | — |
| Riser form boards | 2× lumber 7 in high × 4 ft | 3 | — |
| Side forms | stepped profile, 58 in long × 21 in high | 2 | — |
| Fill / sub-base (optional) | compacted gravel can replace the core of large steps | — | — |
Prices are what you enter under Advanced options. Estimates only — check stock and pricing with your supplier.
Quick answer Three 7 in steps with 11 in treads, 4 ft wide, up to a 36 in deep landing need 30.16 cu ft (1.12 cu yd) of concrete with 10% waste — 51 bags of 80 lb premix, 4,080 lb in all, so ready-mix is worth pricing. Total rise is 21 in. The metric equivalent (3 × 18 cm, 28 cm treads, 1.2 m wide, 90 cm landing) needs 0.84 m³. Volume = width × riser × (tread × n(n − 1)/2 + landing × n).
Method & assumptions
Lower steps = Riser × Tread × (1 + 2 + … + (n − 1)) Landing = Riser × n × Landing depth Volume = Width × Riser × (Tread × n(n − 1) ÷ 2 + Landing × n) Bags = Volume × (1 + waste %) ÷ yield per bag
- n
- number of risers
- Riser
- height of each step
- Tread
- depth of each step below the landing
- Landing
- depth of the top platform (enter the tread depth if there is none)
Assumptions & limits
- Solid steps on a prepared base, all the same riser height and tread depth.
- Every step runs full width; wing walls, flared sides and a nosing are not included.
- Large steps are often built with a compacted gravel core to save concrete — subtract that volume if you do. A 4 in shell over that core is an editorial practice on this site, not a cited code thickness.
- Warnings compare imperial riser and tread only with the quoted 7¾ in and 10 in limits. They do not check variation, width, handrails, landings or whether R311.7 applies.
- Footings, frost protection and rebar are not included. Follow the code edition your building department enforces.
Rounding: purchase quantities are always rounded up to whole units as sold. See our methodology.
Diagram
How to use this calculator
- Count the risers — the vertical faces — including the last one up to the landing or door threshold.
- Divide the total height by the number of risers so every riser matches. Where model IRC R311.7 applies, the quoted limit is 7¾ in. It does not cover every outdoor step, and a warning here is not approval.
- Enter the tread depth (front to back). The quoted IRC minimum is 10 in where that section applies. 11–14 in is a comfort range, not a code band.
- Enter the top platform depth used in the volume formula. A door landing under the stair chapter is a separate requirement this calculator does not check. Typing 36 in does not make the stoop compliant.
- Enter the step width, keep 10% waste unless you have a reason to change it, and pick your bag size.
Worked examples
Imperial: 2 risers of 7½ in, 12 in tread, 48 in landing, 5 ft wide
- Volume = 60 × 7.5 × (12 × 1 + 48 × 2) in³ = 48,600 in³
- = 28.1 cu ft; +10% = 30.9 cu ft = 1.15 cu yd
- ≈ 52 × 80 lb bags — order 1¼ yd of ready-mix instead
Metric: 4 risers of 17 cm, 30 cm treads, 1 m wide, 30 cm top step
- Volume = 1 × 0.17 × (0.30 × 6 + 0.30 × 4) = 0.51 m³
- +10% = 0.561 m³ — a small ready-mix load
In depth: concrete steps planning notes
Laying out the rise and run
Start with the total rise: the height from the finished ground (or landing below) to the top surface, usually just below the door threshold. Divide it by a comfortable riser height to get the number of risers, round up, then divide again so every riser is identical. A 22 in rise becomes three risers of 7⅓ in. Outdoor steps are more comfortable a little lower and deeper than indoor stairs; a common rule is that two risers plus one tread should equal about 24–25 in, so a 7 in riser pairs with an 11 in tread and a 6 in riser with a 13 in tread.
Where model IRC R311.7 applies, the quoted 2018 text limits risers to 7¾ in and treads to at least 10 in. That text does not say it covers every outdoor step, and local amendments differ. This calculator only reminds you about those two dimensions. Other stair rules — variation between steps, door landings, width and handrails — are not quoted here and are not checked. Read the edition your building department enforces before you form.
Saving concrete and forming well
Solid steps use a surprising amount of concrete because each step sits on everything below it: three steps up to a 3 ft landing is more than a cubic yard. On larger stoops, builders often fill the core with compacted gravel or rubble and pour a concrete shell over it. Four inches over that core is an editorial practice on this site, not a thickness we are citing from a code. Subtract the core volume to see the savings, and keep the gravel well back from the forms so the faces are full concrete.
Build side forms from plywood cut to the stepped profile, and riser forms from 2× lumber ripped to the riser height with the bottom edge beveled so you can float the tread all the way to the back. Brace the forms well — wet concrete is heavy — and pin the steps to the foundation where your code requires it. Finish with a broom texture for grip, and slope each tread slightly forward so water drains off.
Reference table
| Item | Quoted limit |
|---|---|
| Riser height | not more than 7¾ in (196 mm) |
| Tread depth | not less than 10 in (254 mm) |
Key facts
- Comfort rule
- 2 × riser + tread ≈ 24–25 in
- 3 steps, 4 ft wide, 36 in landing
- ≈ 1.1 cu yd with waste
- 80 lb bags per cu yd
- 45 (at 0.6 cu ft each)
Tips & common mistakes
- Slope each tread about ⅛–¼ in per foot toward the front so water runs off.
- Use 2× lumber riser forms with the bottom edge beveled so you can trowel the full tread.
- A broom finish is far less slippery than a steel-trowel finish on outdoor steps.
- Large stoops are usually poured with ready-mix in one go — mixing 50+ bags by hand risks cold joints.
Frequently asked questions
How much concrete do I need for 3 steps?
For 4 ft wide steps with 7 in risers and 11 in treads up to a 36 in landing, about 27 cu ft (1 cu yd) before waste — roughly 51 × 80 lb bags with 10% extra.
How many bags of concrete for one step?
A single 7 in step, 12 in deep and 4 ft wide, is 2.33 cu ft — four 80 lb bags, or five with 10% waste.
What is the maximum step height for outdoor stairs?
The quoted model IRC text limits risers to 7¾ in and treads to at least 10 in for stairways that section covers. It does not automatically apply to every garden step, and this calculator does not approve a design. Confirm the edition and local amendments with your building department.
How thick should concrete steps be?
Solid steps on grade use the full profile this calculator measures. If you fill the core with compacted gravel, 4 in of concrete over that core is an editorial practice on this site, not a cited code minimum.
Do concrete steps need rebar?
Rebar or mesh is common, especially where steps tie into a foundation or carry a landing. Follow local code and your plans.
Sources
- Seattle Residential Code 2018 – R311.7.5 stair treads and risers (Chapter 3 PDF) — accessed : “R311.7.5.1 Risers. The riser height shall be not more than 7-3/4 inches (196 mm). … R311.7.5.2 Treads. The tread depth shall be not less than 10 inches (254 mm).”
- Quikrete – Concrete Mix (No. 1101) product data sheet — accessed : “40 lb ≈ 0.30 ft³, 60 lb ≈ 0.45 ft³, 80 lb ≈ 0.60 ft³ (17 L) per bag”
- Portland Cement Association – concrete basics — general reference — not cited for a specific figure
Default values (yields, coverage rates and densities) are typical figures from manufacturer literature. Always check the label on the product you buy.
Related calculators
- Concrete Bag CalculatorHow many bags of concrete do you need? Compare 40, 60 and 80 lb or 20, 25 and 30 kg bags, total weight and cost — with the math shown.
- Stair CalculatorWork out the number of steps, riser height, tread depth, total run, stringer length and angle — and check them against common code limits.
- Rebar CalculatorWork out how many 20 ft rebar sticks a slab needs: grid bar count, total length, lap splices, weight, chairs and tie wire.
Learn more in our guides
Method, waste and worked examples: Concrete volume: formulas, waste and examples.
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DIYCalcLab. “Concrete Step Calculator.” Oct 27, 2026. https://diycalclab.com/concrete/concrete-step-calculator/
Estimates only. Verify quantities with your supplier and local building codes. For structural, electrical or safety-critical work, consult a licensed professional. Full disclaimer.