Concrete Steps Calculator
Cubic yards and bags of concrete for a set of steps, plus the fill that cuts it.
Count the risers, including the top one up to the landing.
Riser height. 7 in is typical; code caps it at 7.75 in.
Tread depth front to back. 11 to 12 in is comfortable; 10 in minimum.
Skin thickness if forming over a compacted fill core, usually 4 to 6 in.
You need
0.52 cubic yards
Waste included. Order this much if the steps are poured solid.
- 80 lb bags (solid)
- 24 bags
- Concrete, shell over core
- 0.41 cubic yards
- Gravel core fill
- 0.10 cubic yards
- Finished height
- 21.0 in
- Volume, solid
- 12.8 cu ft
Estimates only. Verify quantities before ordering.
How this is calculated
Solid volume = width (ft) x rise (in) / 12 x run (in) / 12 x N(N+1)/2 for N steps, in cubic feet, divided by 27 for cubic yards, then plus waste. 80 lb bags assume 0.60 cu ft each. The shell estimate is the exposed tread, riser, and side area times the skin thickness, capped at the solid volume; the gravel core is the solid volume minus the shell.
Enter the number of steps, the rise and run of each one, and the width, and this calculator returns the concrete for a solid pour in cubic yards and 80 lb bags. A set of steps is a stack of boxes, each one taller than the last, so the volume grows by the N(N+1)/2 rule rather than in a straight line: adding one step near the top adds more concrete than one near the bottom.
Steps use far more concrete than their footprint suggests, so the calculator also estimates the shell-over-core option: forming a concrete skin over a compacted gravel fill instead of pouring solid. On a tall flight that can halve the concrete you buy. The shell figure is an estimate, since it depends on how you form it; the solid figure is exact.
Concrete for common step counts
Rows are 4 ft wide at a 7 in rise and 11 in run, with 10% waste, a 5 in shell, poured solid unless you fill the core. One cubic yard is about 45 of the 80 lb bags.
| Steps | Solid (cu yd) | 80 lb bags | Shell (cu yd) |
|---|---|---|---|
| 2 steps | 0.26 cubic yards | 12 bags | 0.26 cubic yards |
| 3 steps | 0.52 cubic yards | 24 bags | 0.41 cubic yards |
| 4 steps | 0.87 cubic yards | 40 bags | 0.59 cubic yards |
| 5 steps | 1.31 cubic yards | 59 bags | 0.78 cubic yards |
| 3 steps, 5 ft wide | 0.65 cubic yards | 30 bags | 0.49 cubic yards |
| 4 steps, 6 ft wide | 1.31 cubic yards | 59 bags | 0.79 cubic yards |
Footings, frost, and settling
Steps fail at the bottom, not the top. A set of steps is heavy and concentrated, and if it bears on soft or frost-susceptible soil it settles or heaves away from the house, opening a gap at the door and cracking the slab. In a freezing climate the base needs to reach below the frost line, either as a poured footing or as a deep bed of compacted, free-draining gravel that gives water somewhere to go.
Where the steps meet the house, tie them to the existing foundation with steel dowels drilled and epoxied into the footing. Without that connection the steps and the house move independently through freeze and thaw cycles, and the joint between them works open over a few winters. The alternative, a fully floating set of steps on a generous gravel base, is acceptable for low stoops but less reliable for a tall flight.
Mix, reinforcement, and finish
Use a 4,000 psi mix for exterior steps and ask for air entrainment anywhere that freezes, since steps take the full force of weather and de-icing salts on every exposed face. Bagged high-strength mixes are typically around 4,000 psi already; for a truck pour, specify it on the ticket.
Reinforce the shell with welded wire mesh or rebar held in the middle of the skin on chairs, not laid on the fill. Steps crack at the corner where the tread meets the riser, so a continuous nose bar along each step edge is cheap insurance. Tool a slight radius on every nosing rather than leaving a sharp arris, which chips under foot traffic and freeze damage.
Finish the treads with a broom texture for grip, since a smooth troweled surface on an exterior step is dangerously slick when wet or icy. Slope each tread about a quarter inch per foot toward the front so water sheds, and cure the concrete by keeping it damp for several days, which matters as much on steps as on any slab.
Common questions
How much concrete do concrete steps need?
Multiply width by rise by run (both in feet) by N(N+1)/2 for N steps to get the solid cubic feet, then divide by 27 for cubic yards. A 4 ft wide stoop of 3 steps at a 7 in rise and 11 in run is about 12.8 cubic feet poured solid, roughly half a cubic yard or 22 to 24 of the 80 lb bags with waste.
Why do steps use so much more concrete than a slab?
Because you fill the whole solid wedge from grade up to the top tread, not a thin layer. The same ground footprint built as four steps holds about four times the concrete of a 4 inch slab. That is why step counts of three and up are usually poured over a compacted fill core rather than solid.
Can I fill the middle of concrete steps to save concrete?
Yes. For anything taller than a couple of low steps, backfill the interior with compacted gravel or clean rubble and pour only a 4 to 6 inch concrete skin over the treads, risers, and exposed sides. The core carries the bulk, so you buy far less concrete. This calculator's shell figure estimates that skin.
What are the rise and run limits for steps?
Most jurisdictions follow the residential stair rule: a maximum riser of 7.75 inches and a minimum tread of 10 inches, with every riser within about 3/8 inch of the others. Exterior treads are often 11 to 12 inches for comfort and should slope about 1/4 inch per foot to shed water.
Do concrete steps need a footing?
In freezing climates, yes: steps should bear on a footing below the frost line or on compacted gravel that drains, or they heave and crack as the ground freezes and thaws. Tie the steps to the house footing with dowels where possible so the two do not move independently.