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Concrete steps calculator

Solid poured stairs — stacked step cross-sections × width.

Most pours order 5–10% extra for spillage and over-excavation.

Estimated volume

0.79cubic yards· 0.606 m³· 21.39 ft³
Bag sizeYield per bagBags needed
40 lb0.3 ft³72
60 lb0.45 ft³48
80 lb0.6 ft³36
25 kg0.413 ft³52
30 kg0.496 ft³44
Planning estimate. Bag counts assume the yields above; check the yield printed on your bag, and allow extra for over-excavation and spillage. Structural and load-bearing work must follow your local building code and an engineer's specification.

Premium · cost estimator

What this pour costs

Bagged
$234.00
36 × 80 lb
Ready-mix
$132.00
0.8 yd³ ordered

Prices are yours to set and stay in this browser. Ready-mix suppliers usually have a minimum load and a short-load surcharge — check before comparing.

Premium · project

Multi-pour project & order sheet

Add this pour to a saved project to total several pours into one order, then print a clean order sheet with the bag counts and yardage to hand your supplier.

Projects are stored in this browser only — nothing is uploaded and there is no account.

Formwork

How the volume is measured

riserunarea = R·T·n(n+1)/2× widthSOLID POURED STAIRS

How this calculator works

A solid poured staircase is a stack of rectangular blocks: the cross-section area is rise × run × n(n+1)/2 for n steps, and the volume is that area times the stair width. Seven-inch rises with eleven-inch runs are a comfortable, code-typical stair.

The volume is then converted to cubic yards (27 cubic feet to the yard) and cubic metres, and divided by each bag's yield to give a bag count — always rounded up, since you cannot buy part of a bag. Bag yields follow the published premix figures: 0.30 ft³ for a 40 lb bag, 0.45 ft³ for 60 lb and 0.60 ft³ for 80 lb, with metric bags scaled from the same mixed density.

Add a waste allowance for anything real: over-excavated trenches, uneven sub-grade, spillage and what stays in the mixer. Five to ten percent is typical; a rough excavation can need more.

Worked examples

Common steps sizes, already calculated

Concrete for 2 solid steps, 3 ft wide0.18 yd³9 × 80 lb bagsConcrete for 2 solid steps, 4 ft wide0.24 yd³11 × 80 lb bagsConcrete for 3 solid steps, 3 ft wide0.36 yd³17 × 80 lb bagsConcrete for 3 solid steps, 4 ft wide0.48 yd³22 × 80 lb bagsConcrete for 4 solid steps, 3 ft wide0.59 yd³27 × 80 lb bagsConcrete for 4 solid steps, 4 ft wide0.79 yd³36 × 80 lb bagsConcrete for 5 solid steps, 3 ft wide0.89 yd³41 × 80 lb bagsConcrete for 5 solid steps, 4 ft wide1.19 yd³54 × 80 lb bagsConcrete for 6 solid steps, 3 ft wide1.25 yd³57 × 80 lb bagsConcrete for 6 solid steps, 4 ft wide1.66 yd³75 × 80 lb bags

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