DIY Cost Tools
Stair Calculator
Estimate riser count, actual riser height, tread count, total run, stringer length, lumber quantities, and basic material cost.
Measure: Use finished elevations and verify every dimension against the locally adopted building code and an approved plan.
How the estimate works: The calculator uses your measurements, unit conversions, waste allowance, and product coverage to create a planning quantity. Review the formula shown above, then read the matching guide below before ordering. See How Our Calculators Work for assumptions and limitations.
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Stairs are safety-critical and code-regulated. Verify every dimension and consult a qualified professional when needed. Read our advertising disclosure.
How this calculator works
Riser count is total rise divided by the target maximum riser and rounded up. The calculator then derives equal riser height, tread count, total run, sloped stringer length, and lumber allowances.
Finished dimensions matter
Flooring, landings, tread thickness, nosing, and deck surfaces can change the first and last riser. Measure from finished floor to finished floor and lay out the entire stair before cutting stringers.
Safety and code notice
Stairs are life-safety construction. Maximum riser height, minimum tread depth, headroom, width, landings, handrails, guards, stringers, and fastening requirements vary. Use approved plans and local code requirements rather than relying on this planning calculator alone.
Read the complete stair calculator planning guide.
Stair-layout example
A total rise of 105 inches divided by a target rise of 7.5 inches produces 14 risers. The actual riser height is then 105 ÷ 14 = 7.5 inches. A typical straight stair has one fewer tread than risers when the upper floor serves as the last tread, so the planning count is 13 treads. Total run depends on the selected tread depth and nosing details.
Verify every dimension against code and site conditions
Measure finished-floor to finished-floor height after accounting for flooring thickness. Check headroom, landing size, stair width, guards, handrails, openings, stringer capacity, fastening, and consistent riser and tread dimensions. The calculator is a layout aid, not structural design or code approval. Field conditions and local requirements control the final stair.