What are the UK Building Regulations for stairs?

Under Approved Document K (2013), domestic stairs must have a maximum riser height of 220mm, minimum going of 220mm, maximum pitch of 42°, and minimum headroom of 2000mm. The 2R + G formula (twice the rise plus the going) should fall between 550mm and 700mm for comfortable use.

How do I measure total rise for a staircase?

Total rise is the vertical distance from finished floor level (FFL) at the bottom to finished floor level at the top. This must include the thickness of floor finishes on both levels. Measure accurately with a laser level or spirit level and tape measure from the exact point where the staircase will start.

What is the ideal riser height and going depth?

For domestic stairs, a riser height of 170–190mm and going of 240–260mm provides a comfortable staircase. The 2R + G value should ideally be around 600–630mm. Going too shallow on the rise or too deep on the going makes stairs feel tiring; too steep feels unsafe.

How many steps do I need for a standard UK storey height?

A typical UK storey height (floor to floor) is 2600mm. With a 200mm riser, this gives 13 risers (12 treads). With a 185mm riser, you would need 14 risers (13 treads). The exact number depends on your specific floor-to-floor measurement.

How do I calculate spindle spacing for my staircase?

Spindle spacing must comply with the 100mm sphere rule — a 100mm sphere must not be able to pass through any gap. Use our Spindle Spacing Calculator to work out the exact number of balusters and gap width for your balustrade length.

Staircase Calculator — How Many Steps and What Pitch for UK Building Regs?

Staircase Calculator — UK Building Regs Part K Compliance

Calculate stair dimensions compliant with UK Building Regulations Part K. Enter your total rise and available going to get riser height, going depth, pitch angle and compliance checks.

Total Rise (Floor to Floor)

Vertical distance from FFL bottom to FFL top

Available Going (Horizontal Run)

Horizontal distance available for the staircase

Staircase Width

Part K minimum is 800mm between walls

Available Headroom

Part K minimum is 2000mm

How We Calculate This

This calculator determines the optimal staircase geometry based on your total rise (floor-to-floor height) and available going (horizontal run). It checks all results against UK Building Regulations Approved Document K.

Formulas used

Number of risers = Total Rise / Target Riser Height (rounded to nearest whole number)
Actual riser height = Total Rise / Number of Risers
Going depth = Available Going / (Number of Risers - 1)
Pitch angle = arctan(Riser Height / Going Depth)
Stringer length = √(Total Rise² + Available Going²)

Part K compliance checks

Maximum riser: 220mm for private stairs
Minimum going: 220mm for private stairs
Maximum pitch: 42° for private stairs
Minimum headroom: 2000mm measured vertically above the pitch line
2R + G rule: Twice the riser plus the going should be 550–700mm
Rise × Going: Should not exceed 50,000 for domestic stairs

Standards

All checks reference Approved Document K (2013 edition with 2019 amendments) for private domestic stairways. Utility stairs, common stairs in flats, and institutional stairs have different requirements. All risers must be equal in height and all goings must be equal in depth.

Frequently Asked Questions

Last updated: February 2026

All calculations are estimates. Verify with your supplier.

Staircase Calculator — UK Building Regs Part K Compliance

How We Calculate This

Formulas used

Part K compliance checks

Standards

Frequently Asked Questions

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