Concrete Steps Calculator: Yards and Bags for Porch Stairs
Enter risers, rise, tread and width to get cubic yards plus Quikrete 80 / 60 / 40 lb bag counts. Tables below use the cumulative solid-stack formula in Calcs.concreteSteps — not a flat slab shortcut.
Quick answer
Three solid porch steps 36 in wide × 11 in tread × 7.5 in riser need 0.420 yd³ with 10% waste (10.312 ft³ exact) — about 19 × 80 lb Quikrete bags (0.60 ft³ each), 26 × 60 lb, or 38 × 40 lb. Add a landing only when that platform is part of the same pour.
Updated 2026-10-24 · Uses Calcs.concreteSteps (cumulative solid stack). Bag yields from Quikrete Concrete Mix data sheets (same figures as our Quikrete calculator). Flat pads use the concrete slab calculator; round piers use the sonotube calculator.
How much concrete for my steps?
All step dimensions in inches. Defaults: 3 risers × 7.5 in rise × 11 in tread × 36 in width, 10% waste. Landing fields are optional — leave blank if there is no separate platform. Bag yields: 80 lb = 0.60 ft³, 60 lb = 0.45 ft³, 40 lb = 0.30 ft³.
Result
How do I use the concrete steps calculator?
- Count the risers in the poured flight (a 3-step porch usually has 3 risers).
- Enter riser height and tread depth in inches, and the full stair width in inches (not feet).
- If the top platform is part of the same pour, enter landing length, width and thickness; otherwise leave those fields blank.
- Keep 5–10% waste unless you are topping off an almost-full form.
- Pick 80, 60 or 40 lb bags to match what the yard stocks; yields match Quikrete Concrete Mix sheets already cited on this site.
What formulas does the calculator use?
It runs TrueToolCalc’s cumulative solid-stack function, then divides volume by published Quikrete bag yields.
| Quantity | Formula | Source / assumption |
|---|---|---|
| Step i volume | width × tread × (i × riser) | Solid rectangle from grade up to that tread (i from bottom = 1…n) |
| Steps total | width × tread × riser × n(n+1)/2 | Calcs.concreteSteps triangle sum |
| Landing (optional) | length × width × thickness | Independent slab; blank fields = 0 |
| Cubic yards | ft³ ÷ 27; × (1 + waste) | Ready-mix / bag order quantity |
| 80 lb bags | ceil(ft³ × (1 + waste) ÷ 0.60) | Quikrete Concrete Mix No. 1101: 0.60 ft³ per 80 lb bag |
| 60 lb bags | ceil(ft³ × (1 + waste) ÷ 0.45) | Same sheet family as site Quikrete page |
| 40 lb bags | ceil(ft³ × (1 + waste) ÷ 0.30) | Same sheet family as site Quikrete page |
Porch concrete steps by size (no separate landing)
Each row is one solid flight at 10% waste with no landing. A common 3-step 36 in porch at 7.5 × 11 is 0.420 yd³ / 19 × 80 lb bags; the same geometry 48 in wide scales with width. All rows use Calcs.concreteSteps.
| Steps | Riser | Tread | Width | Exact ft³ | Order yd³ | 80 lb | 60 lb | 40 lb |
|---|---|---|---|---|---|---|---|---|
| 3 | 7 in | 11 in | 36 in | 9.625 | 0.392 | 18 | 24 | 36 |
| 3 | 7 in | 11 in | 48 in | 12.833 | 0.523 | 24 | 32 | 48 |
| 3 | 7.5 in | 11 in | 36 in | 10.312 | 0.420 | 19 | 26 | 38 |
| 3 | 7.5 in | 11 in | 48 in | 13.750 | 0.560 | 26 | 34 | 51 |
| 3 | 7.75 in | 10 in | 36 in | 9.688 | 0.395 | 18 | 24 | 36 |
| 3 | 7.75 in | 10 in | 48 in | 12.917 | 0.526 | 24 | 32 | 48 |
| 4 | 7 in | 11 in | 36 in | 16.042 | 0.654 | 30 | 40 | 59 |
| 4 | 7 in | 11 in | 48 in | 21.389 | 0.871 | 40 | 53 | 79 |
| 4 | 7.5 in | 11 in | 36 in | 17.188 | 0.700 | 32 | 43 | 64 |
| 4 | 7.5 in | 11 in | 48 in | 22.917 | 0.934 | 43 | 57 | 85 |
| 4 | 7.75 in | 10 in | 36 in | 16.146 | 0.658 | 30 | 40 | 60 |
| 4 | 7.75 in | 10 in | 48 in | 21.528 | 0.877 | 40 | 53 | 79 |
| 5 | 7 in | 11 in | 36 in | 24.062 | 0.980 | 45 | 59 | 89 |
| 5 | 7 in | 11 in | 48 in | 32.083 | 1.307 | 59 | 79 | 118 |
| 5 | 7.5 in | 11 in | 36 in | 25.781 | 1.050 | 48 | 64 | 95 |
| 5 | 7.5 in | 11 in | 48 in | 34.375 | 1.400 | 64 | 85 | 127 |
| 5 | 7.75 in | 10 in | 36 in | 24.219 | 0.987 | 45 | 60 | 89 |
| 5 | 7.75 in | 10 in | 48 in | 32.292 | 1.316 | 60 | 79 | 119 |
Bag chart: 36 in porch steps at 7.5 × 11
Fixed width 36 in, riser 7.5 in, tread 11 in, no landing. Bag counts grow with the triangle number n(n+1)/2, so going from 3 to 5 steps more than doubles the order (19 → 48 × 80 lb at 10% waste).
| Steps | Exact ft³ | Exact yd³ | Order yd³ | 80 lb | 60 lb | 40 lb |
|---|---|---|---|---|---|---|
| 2 | 5.156 | 0.191 | 0.210 | 10 | 13 | 19 |
| 3 | 10.312 | 0.382 | 0.420 | 19 | 26 | 38 |
| 4 | 17.188 | 0.637 | 0.700 | 32 | 43 | 64 |
| 5 | 25.781 | 0.955 | 1.050 | 48 | 64 | 95 |
| 6 | 36.094 | 1.337 | 1.470 | 67 | 89 | 133 |
Worked example: 3 porch steps, no landing
A front porch with three 7.5 in risers, 11 in treads and 36 in width needs 0.420 yd³ with 10% waste. The stack is three rectangles from grade: 7.5, 15 and 22.5 in tall — not three identical 7.5 in slabs.
| Step | Working (in) | Volume |
|---|---|---|
| Step 1 (from bottom) | 36 × 11 × 7.5 | 2970 in³ = 1.719 ft³ |
| Step 2 (from bottom) | 36 × 11 × 15 | 5940 in³ = 3.438 ft³ |
| Step 3 (from bottom) | 36 × 11 × 22.5 | 8910 in³ = 5.156 ft³ |
| Triangle sum | 36 × 11 × 7.5 × (1+2+3) | 10.312 ft³ = 0.382 yd³ |
| + 10% waste | 0.382 × 1.10 | 0.420 yd³ |
| 80 lb bags | 10.312 × 1.10 ÷ 0.60 | 19 bags |
| 60 lb / 40 lb | same total ÷ 0.45 / 0.30 | 26 / 38 bags |
Landing thickness changes the order
For the same 3-step 36×11×7.5 flight, a full-height solid landing 24 in deep (thickness = 3 × 7.5 = 22.5 in) jumps the order to 0.878 yd³ / 40 × 80 lb bags. A 4 in thick landing slab on compacted fill on the same footprint is only 0.502 yd³ / 23 × 80 lb bags. Enter thickness deliberately.
| Landing thickness | Landing ft³ | Total order yd³ | 80 lb bags |
|---|---|---|---|
| None | 0 | 0.420 | 19 |
| 4 in (slab on fill) | 2.000 | 0.502 | 23 |
| 22.5 in (full stack height) | 11.250 | 0.878 | 40 |
Result looks wrong? Check these
- Width typed in feet: the width field is inches. Typing
3when you mean 3 ft (36 in) under-orders by 12× — that mistaken run is 0.035 yd³ vs 0.420 yd³ for 36 in. - Riser typed as total rise: enter one riser height, not n × riser. Typing 22.5 for a 3-step porch (instead of 7.5) inflates the stack to 1.260 yd³ / 57 × 80 lb bags.
- Landing thickness = full height vs thin slab: full-height solid platforms use ≈ n × riser; thin landings on fill use slab thickness only (see table above).
- Floating / hollow stairs: this tool is for solid stacked steps. Carriage/throat geometry needs a different calculator.
- Bags look high vs a ready-mix quote: short porch jobs are often bag-only; ready-mix minimum loads can exceed the whole flight.
- Treating stairs as one slab: width × overall height × total run over- or under-counts. Use the triangle sum, not a single rectangle.
When not to use this tool
- Code layout: rise/run uniformity, handrails and landings follow your local code (often based on IRC R311.7). This page estimates volume only — typical planning inputs are not code approval.
- Frost and footings: stoops in frost climates need footings below frost depth; volume here does not size the footing. Use the concrete footing calculator for a continuous footing once the plan sets width and depth.
- Reinforcement / structural design: rebar, dowels into the house foundation and soil bearing are engineer or building-department items.
- Tall or attached flights: call a contractor or engineer when the stair is more than a short porch, is structural, or ties into a foundation wall.
Frequently asked questions
How much concrete for 3 concrete steps?
Three solid steps 36 in wide × 11 in tread × 7.5 in riser need 10.312 ft³ (0.382 yd³). With 10% waste that is 0.420 yd³ — about 19 × 80 lb Quikrete bags (0.60 ft³ each), 26 × 60 lb, or 38 × 40 lb.
What formula does this concrete steps calculator use?
Cumulative solid stack: volume of step i (from the bottom) = width × tread × (i × riser); sum i = 1…n, which equals width × tread × riser × n(n+1)/2. Optional landing adds length × width × thickness. Then ft³ ÷ 27 = yd³. Implemented as Calcs.concreteSteps.
How many Quikrete bags for concrete porch steps?
Divide the stair volume (with waste) by Quikrete Concrete Mix yields: 80 lb = 0.60 ft³, 60 lb = 0.45 ft³, 40 lb = 0.30 ft³. A 3-step 36×11×7.5 porch at 10% waste needs 19 × 80 lb bags.
Do I include the top landing in the concrete steps calculator?
Yes if the landing is part of the same pour. Enter landing length, width and thickness. A full-height solid landing uses thickness ≈ n × riser; a thin slab on compacted fill uses the slab thickness only (often 4 in). Leave landing fields blank when there is no separate platform.
Solid stacked steps or floating stairs with a throat?
This page sizes solid stacked porch/stoop steps (filled under each tread). Floating stairs with a carriage/throat need a different model — Omni-style throat-depth calculators cover that geometry; do not use this tool for hollow stairs.
What riser and tread sizes should I use?
Common US residential planning ranges often cited from IRC R311.7 are about 7–7¾ in risers and 10–11 in treads. Treat those as typical planning inputs only — not code approval. Verify your local code edition, amendments, and the building department.
Should I add waste when ordering for steps?
Yes. 5–10% covers form leak, over-excavation and chute cling. This calculator defaults to 10%. Small porch jobs are often bag-only; ready-mix minimum loads can exceed a short flight.
When should I not use this concrete steps calculator?
Do not use it for structural design, frost-depth footings under the stoop, reinforcement schedules, or code-compliant rise/run layout. Call a contractor or engineer when the flight is tall, attached to a foundation, or in a frost zone that needs a proper footing.
Sources
- TrueToolCalc
Calcs.concreteStepsin js/calcs.js: V_steps = width × tread × riser × n(n+1)/2; optional landing = L × W × thickness (same solid-stack family as common rectangular stair estimates). - Quikrete, Concrete Mix No. 1101 data sheet: 80 lb bag yields 0.60 ft³; 60 lb = 0.45 ft³; 40 lb = 0.30 ft³ (retrieved 2026-10-15; cited on our Quikrete calculator).
- IRC R311.7 stair geometry: cited only as typical US residential planning ranges (about 7–7¾ in risers, 10–11 in treads) — not code approval. Verify your edition, local amendments and the building department.
- Flat slabs and round piers are different shapes — use the concrete slab calculator or sonotube calculator instead of forcing stair math onto those jobs.
Related calculators & guides
- Concrete slab volume
- Bags of premixed concrete
- Quikrete bag yields
- Concrete column / pier volume
- Sonotube concrete calculator
- Continuous footing volume
- Slab plus gravel base
- Cement / mix ratio calculator
Last updated 2026-10-24 · About TrueToolCalc and how we check numbers · Found an error? Use the contact page.