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)
UK Market PricesFills in the material cost fields with current UK market prices. You can review and edit each price before applying.
Results
Risers
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steps
Treads
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boards
Stringer length
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metres each
Total going
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metres
Stair Geometry
| Parameter | Value | UK Building Regs | Status |
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Material List
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Frequently Asked Questions
What are the Building Regulations for stair dimensions?
Under Approved Document K for private stairs (within a single dwelling): max rise 220 mm; min going 220 mm; max pitch 42°; formula 2R + G = 550-700 mm. Minimum headroom: 2.0 m measured vertically from the pitch line. Common/commercial stairs: stricter - max rise 190 mm, min going 250 mm.
How do I calculate the number of steps for a staircase?
Measure total floor-to-floor height (finished floor to finished floor). Divide by target rise. Example: 2600 mm ÷ 200 mm = 13 steps. Verify rise is within limits (max 220 mm). Calculate going: G = 600 - (2 x Rise) as a starting point, adjust to meet min 220 mm. All steps in a flight must have identical rise and identical going.
What is the minimum handrail height for a staircase?
Approved Document K: handrail height 900-1000 mm above the pitch line (measured from tread nosing to top of handrail). At landings: minimum 900 mm. Stairs wider than 1000 mm: handrails required on both sides. Open sides: balustrade required - no opening must allow a 100 mm sphere to pass through.
What is the 100 mm sphere rule for balustrading?
Approved Document K: no opening in balustrade or guarding should allow a 100 mm sphere to pass through - prevents children becoming trapped between balusters. For vertical balusters: maximum spacing approximately 99 mm between centres. Gap at base (between bottom rail and floor/string): also under 100 mm. Avoid horizontal rails - they act as a climbing frame for children.
What is the minimum headroom required over a staircase?
Approved Document K: minimum 2000 mm clear headroom measured vertically from the pitch line to any overhead obstruction. Must be maintained over the full width of the stair. Under sloping ceilings (loft conversions): 2000 mm must be present at the centre of the stair width. Alternating tread (space-saver) stairs: reduced headroom may be acceptable - confirm with building control.
Do I need Building Regulations approval to replace a staircase?
Like-for-like replacement (same position, same dimensions): generally a permitted repair - no Building Regulations approval needed. Altering stair geometry (different number of steps, different rise or going, new position): Building Regulations approval required and new stair must comply with Approved Document K. Stair work forming part of a larger project (extension, loft conversion) will be inspected as part of those works.