Straight stair materials calculator
Work out riser height, tread depth, angle and concrete or timber volumes for a staircase; 2.8 m rise over 15 steps gives 187 mm risers.
- Runs in your browser
- No upload
- Instant result
Quantity estimate only. This does not approve structural safety, load capacity, drainage, fire resistance or building-code compliance. Verify the design and local requirements with a qualified professional. Purchase quantities round up to whole packs.
Assumptions & formula
Formula and assumptions
w = Waste allowance/100; r=H/n; t=L/n; V=Wt r n(n+1)(1+w)/2; Vwood=W(L+H)T(1+w)
Equal steps in a straight stair. Concrete assumes a solid stepped prism filled to the ground; an open underside or slab/stringer stair needs a different model. Timber includes treads and risers only, excludes stringers and fasteners. Geometry is a quantity estimate, not a safe-stair or code approval.
The prefilled values are editable examples, not product specifications. Enter your supplier’s yield, density, coverage and packaging values, and add an allowance for overlaps, compaction and cuts where needed.
Purchase counts use the exact entered decimals and unit factors, without a rounding tolerance that could discard a real remainder. π and irrational square roots use enclosing bounds; ambiguous counts produce an error. Counts must be safe integers.
Results
Enter values and press Calculate to see the result here.
How to use this calculator
- Set inputs and units
Enter the total rise and run, the width, the number of steps and the timber thickness, and supply the concrete bag yield separately.
- Calculate
Check this worked example: rise1 m,run2 m,width1 m,steps4,thickness0.02 m,waste0%,bagYield0.05 m³ → riser0.25 m,tread0.5 m,concrete1.25 m³,wood0.06 m³,bags25
- Results
Read the rise and tread of each step separately from the total volumes. The diagram shows a solid stepped concrete model.
Questions and limits
Why are concrete and timber volumes different?
Concrete adds up stacked step blocks. Timber covers the tread and riser surfaces at your thickness, not stringers or a hollow shell.
Which input errors should I correct?
Use 1–200 whole steps and positive dimensions. The geometry limits accepted here are not building-code approval.
What does this calculation leave out?
No headroom, landings, handrails, reinforcement, load capacity or validation against stair-safety rules in your area.