What are the Part K staircase dimensions for domestic properties?

For domestic stairs under Building Regulations Part K: rise must be 150-220mm, going must be 220-300mm, maximum pitch is 42 degrees, and the headroom must be at least 2000mm. The comfort formula 2R+G should be between 550-700mm. All risers and goings must be equal throughout the flight.

What is the 2R+G rule for staircases?

The 2R+G rule (also known as the Blondel formula) states that twice the rise plus the going should equal 550-700mm for a comfortable staircase. The ideal target is around 620mm. For example: with a 190mm rise and 240mm going: 2(190) + 240 = 620mm — perfect. This formula has been used since the 17th century to design comfortable stairs.

What is the maximum pitch for a domestic staircase?

The maximum pitch (angle) for a domestic staircase is 42 degrees under Part K. For common stairs in flats and other non-domestic buildings, the maximum is 38 degrees. The pitch is determined by the ratio of rise to going — steeper stairs are less comfortable and more dangerous, hence the regulatory limit.

What is the minimum headroom for a staircase?

The minimum headroom above the staircase pitch line is 2000mm (2m) measured vertically. This must be maintained over the full width of the staircase and at all points along its length. In loft conversions where headroom is restricted, 1800mm may be acceptable in some circumstances — check with building control.

What handrail height is required on stairs?

Handrails must be between 900mm and 1000mm measured vertically from the pitch line (the line connecting the nosings). At least one handrail is required on stairs less than 1m wide, and handrails on both sides for stairs 1m or wider. Handrails must be continuous and graspable, with a profile of 32-50mm diameter.

TradeCalculator

Staircase Compliance Calculator

Check your staircase design against Building Regulations Part K: rise, going, pitch, 2R+G comfort rule, headroom and handrail height.

Building Type

Affects permitted dimensions

Total Rise (floor to floor)

Finished floor to finished floor

Individual Rise

Height of each step

Going (tread depth)

Nosing to nosing depth

Headroom

Min measured from pitch line

Stair Width

Clear width between walls/strings

How We Calculate This

This calculator checks your staircase dimensions against Building Regulations Part K for England and Wales. It evaluates rise, going, pitch angle, the 2R+G comfort formula, headroom and handrail height.

The formula

Risers = Total rise ÷ Individual rise
Pitch = arctan(Rise ÷ Going)
2R + G = (2 × Rise) + Going (target 550-700mm)
Stair length = (Risers - 1) × Going

Part K limits

Domestic: Rise 150-220mm, Going 220-300mm, Pitch max 42°
Common stairs: Rise 150-190mm, Going 250-300mm, Pitch max 38°
All: Headroom min 2000mm, Handrail 900-1000mm
2R+G: 550-700mm (ideal ~620mm)

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.