Staircase Calculator

UK Building Regulations, and Approved Document K in particular, set strict requirements for domestic staircases. The maximum rise per step is 220 mm and the minimum going, meaning the tread depth, is 220 mm. The pitch must not exceed 42°. Twice the rise plus the going, usually written as 2R + G, should also fall between 550 mm and 700 mm if the flight is to feel comfortable underfoot rather than merely legal.

This calculator takes the total floor-to-floor height and the horizontal distance you have available, then works out the number of treads, the individual rise, the going and the overall length of the flight. Each result is checked against the regulations, and any dimension that falls outside the permitted limits is flagged rather than quietly passed over.

Headroom must be at least 2.0 m, measured vertically from the pitch line, and the calculator also reports the stairwell opening length the flight will need. For a standard floor-to-floor height of 2.6 m, most staircases come out at 12 or 13 risers with a horizontal run of roughly 3.0 to 3.5 m once a landing is allowed for. Take the height up to 2,700 mm, which is common in older British houses, and you are looking at 14 risers of 192.8 mm each, goings of 220 to 250 mm and a run of about 3,360 mm before the landings at either end.

Other dimensions in Part K matter just as much as the rise and going. Handrails sit 900 mm to 1,100 mm above the pitch line. Gaps in the balustrade must stay under 100 mm, tested by whether a 100 mm sphere can pass through, which is the standard child-safety check. Minimum width is 800 mm, although some councils ask for 900 mm. Open risers are permitted, subject to the same 100 mm gap rule, while spiral staircases fall under separate rules and are generally accepted only as secondary access.

Most British homes have closed risers boxed in at the side, which hides the space beneath and makes it usable for storage. Open risers read as lighter and more modern, often paired with a glass balustrade, though the sphere rule still applies. The side detail has its own vocabulary: a string stair shows its stringers, a boxed or wall stair conceals them, and a cut stringer leaves the tread ends on display. Conservation areas normally expect a traditional design. Standardised pre-built flights from Magnet, Wickes or B&Q run £200 to £800, while listed and older properties usually need custom carpentry.

An off-the-shelf softwood staircase costs £200 to £500, with installation adding £400 to £800, so £600 to £1,300 all in. Mid-range oak is £800 to £2,500 supplied plus £500 to £1,000 to fit, and bespoke hardwood starts around £3,000 and can pass £15,000. Individual parts cost far less: stairlift removal is £150 to £300, spindles £15 to £30 each and a newel post £80 to £200. A loft conversion staircase, steeper and often made to measure, typically runs £1,500 to £4,000, and traditional carpentry in a listed building can reach £5,000 to £20,000.

Squeaking treads are almost always loose nails or screws where the tread meets its riser, and the cure is to re-screw from underneath or work PVA glue into the joint. Sagging is structural, so pay a stair surveyor £80 to £200 to assess it before doing anything else. Carpet worn through to splintered treads is worth sanding and refinishing at £100 to £300 before you recarpet or lay hardwood or laminate. A wobbling newel post needs securing back to the joist or beam below, loose balusters can be dowelled and glued or replaced, and stair gates for young children or pets belong at both ends of the flight and should meet BS EN 1930:2011.