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Staircase Calculator

Calculate riser and tread counts, stringer length, timber quantities, baluster counts, and full material costs. Includes UK Building Regulations compliance check.

Staircase Calculator

Risers, treads, stringers, balustrade, and job costing - with Building Regulations compliance check.

Finished floor level to finished floor level. Typical UK: 2400-2700 mm.
UK Building Regs: 150-220 mm. Comfortable: 170-180 mm.
UK Building Regs: min 220 mm. Comfortable: 240-280 mm.
UK Building Regs: min 800 mm for private stairs.
Typical 15-25 mm overhang beyond riser face.
Softwood: 32 mm. Hardwood: 28-40 mm.
Leave 0 to use calculated riser height.
Open-riser stairs omit riser boards.
Cut stringers from 225-250 mm deep structural timber.
Newel posts, balusters, and handrail.
UK regs: max 99 mm gap (100 mm sphere rule).
Minimum 2 (bottom & top). Add 1 per quarter-turn landing.

Job Costing (optional)

Results

Risers
-
steps
Treads
-
boards
Stringer length
-
metres each
Total going
-
metres

Stair Geometry

ParameterValueUK Building RegsStatus

Material List

UK Building Regulations

Parameter Private stair
Max riser height220 mm
Min riser height150 mm
Min tread depth (going)220 mm
Max pitch angle42°
Min stair width800 mm
Min headroom2000 mm
Baluster gap (sphere rule)< 100 mm
Min handrail height900 mm

Source: Approved Document K (2013). Always confirm with your local Building Control authority.

The 2R + G Rule

A comfortable staircase satisfies:

2R + G = 550–700 mm

Where R = riser height and G = tread going. The ideal target is around 630 mm. Our results show your 2R+G value with a pass/warn/fail indicator.

Stringer Notes

  • Cut stringers from C24 or better structural timber, typically 225×47 mm or 250×47 mm.
  • The calculated stringer length is the diagonal run - add 300–400 mm to each end for bearing and cut waste.
  • Closed stringers have treads and risers housed into routed grooves. Open stringers have treads notched over the top edge.
  • Always check the remaining stringer depth (below the notches) is at least 100 mm for structural adequacy.

Fitting Tips

  • Always measure total rise to finished floor level - not sub-floor.
  • The bottom riser is often reduced by the tread thickness to keep all steps equal once treads are fitted.
  • Use glued-and-screwed joints for solid hardwood treads; wedged grooves for softwood flights.
  • Pre-finish undersides of treads before fitting to prevent squeaks.
  • Newel posts should be bolted through the floor joist or fitted with a bolt-down base plate.

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