Stairs Calculator UK 2025
Calculate staircase dimensions for Building Regulations Part K compliance
Calculate Rise and Going
Enter your total floor-to-floor height and preferred number of steps to calculate the rise and going dimensions.
Calculate Number of Steps
Enter your total height and preferred rise to calculate the optimal number of steps.
Building Regulations Part K Checker
Enter your staircase dimensions to check compliance with UK Building Regulations Approved Document K.
Winder Stairs Calculator
Calculate winder treads for quarter-turn or half-turn staircases with tapered steps.
Stringer Length Calculator
Calculate the stringer length and materials needed for your staircase construction.
UK Building Regulations Part K: Staircase Requirements
Building Regulations Approved Document K sets out the requirements for stairs, ramps, ladders and guards in England. These regulations are designed to ensure staircases are safe for all users, including those with mobility impairments. Scotland, Wales and Northern Ireland have equivalent regulations with similar requirements.
Domestic Private Stairs (Single Dwelling)
For staircases serving a single private dwelling (houses and flats), the following requirements apply:
Key Dimensional Requirements
- Maximum Rise: 220mm (recommended range: 170-220mm)
- Minimum Going: 220mm (recommended range: 220-300mm)
- Maximum Pitch: 42 degrees
- Minimum Headroom: 2000mm measured vertically
- Minimum Width: No specific requirement, but 850mm+ recommended
The 2R + G Formula
The 2R + G formula is the industry-standard method for checking staircase comfort. This formula adds twice the rise (R) to the going (G), and the result should fall within a specific range:
| Stair Type | 2R + G Range | Optimal Value | Example |
|---|---|---|---|
| Domestic Private | 550mm - 700mm | 600mm | Rise 180mm, Going 240mm = 600mm |
| Utility/Loft | 550mm - 700mm | 620mm | Rise 200mm, Going 220mm = 620mm |
| Common/Public | 550mm - 700mm | 600mm | Rise 170mm, Going 260mm = 600mm |
| Institutional | 530mm - 660mm | 580mm | Rise 150mm, Going 280mm = 580mm |
Loft Conversion Staircases
Building Regulations recognise that loft conversions in existing dwellings may face space constraints. Approved Document K allows some relaxations:
Loft Conversion Concessions
- Alternating tread stairs (paddle stairs) may be permitted where space is limited
- Minimum headroom can be reduced to 1900mm on the centreline
- Reduced headroom at edges permitted (1800mm at sides)
- Building Control approval is required in all cases
- Fixed ladder access is only acceptable for occasional access
Handrail Requirements
Handrails are essential safety features for all staircases:
- Height: 900mm - 1000mm from pitch line or floor
- Stairs < 1000mm wide: Handrail required on at least one side
- Stairs ≥ 1000mm wide: Handrails required on both sides
- Open sides: Must have guarding to prevent falls
- Balusters: Maximum 100mm spacing (child safety)
Winder Stairs and Tapered Treads
Winder stairs incorporate tapered treads to change direction. Building Regulations have specific requirements for these:
Winder Tread Requirements
- Minimum going at narrow end: 50mm
- Going measured 270mm from narrow end
- Maximum 3 winders in a consecutive flight
- Uniform going for all tapered treads when measured on centreline
- Quarter-turn typically uses 3 winders for 90° turn
- Half-turn (kite winders) uses 6 winders for 180° turn
Types of Staircases in UK Homes
Straight Flight Stairs
The most common and economical staircase design, consisting of a single straight run of steps. Advantages include:
- Simplest to design and construct
- Most economical option
- Easiest for moving furniture
- Best for accessibility and mobility aids
- Requires adequate linear floor space
Quarter-Turn (L-Shaped) Stairs
Features a 90-degree turn, typically at a landing or using winder treads. Popular in UK homes where space is limited:
- Takes up less floor space than straight stairs
- Landing provides resting point
- Can be positioned in corners
- More visually interesting than straight flight
Half-Turn (U-Shaped) Stairs
Incorporates a 180-degree turn, creating a switchback pattern. Common configurations include:
- Dog-leg: Two flights with half-landing (flights share a newel post)
- Open-well: Two flights with space between
- Kite winder: Uses tapered treads instead of landing
Spiral and Helical Stairs
Space-saving options that wind around a central pole or void. Important considerations:
Building Regulations Restrictions
Spiral stairs can only be used as the main staircase in a loft conversion if there is no alternative and Building Control approves. They must have a minimum clear width of 800mm and going of at least 50mm at the narrow end.
Calculating Total Going Length
The total horizontal distance your staircase needs can be calculated using this formula:
Formula: Total Going = (Number of Treads) x Going
Remember: Number of Treads = Number of Risers - 1
Example: 14 risers with 240mm going = 13 treads x 240mm = 3,120mm total going
Staircase Materials and Construction
Timber Staircases
The most popular choice for UK residential properties, timber staircases offer warmth, versatility and value:
| Timber Type | Characteristics | Typical Cost | Best For |
|---|---|---|---|
| Softwood (Pine) | Light colour, takes stain well, prone to dents | £1,500 - £3,500 | Budget builds, carpet covering |
| Hemlock | Straight grain, stable, good workability | £2,000 - £4,000 | Painted finishes |
| Oak | Durable, attractive grain, prestigious | £4,000 - £10,000+ | Exposed/feature stairs |
| Ash | Hard, flexible, shock-resistant | £3,500 - £7,000 | High-traffic areas |
| Walnut | Rich dark colour, luxury appearance | £6,000 - £15,000+ | Premium properties |
Glass and Metal Staircases
Contemporary designs often incorporate glass treads, steel stringers, or aluminium balustrades. Considerations include:
- Glass treads: Must use laminated toughened glass minimum 21.5mm thick
- Steel stringers: Often powder-coated, require structural calculations
- Glass balustrades: Minimum 10mm toughened glass, frameless designs popular
- Cost: Typically 50-100% more than equivalent timber designs
Staircase Components
Essential Components
- Tread: The horizontal surface you step on
- Riser: The vertical board between treads
- Stringer: The supporting side boards (can be open or closed)
- Newel post: Main vertical posts at top, bottom, and turns
- Balusters: Vertical spindles between handrail and string
- Handrail: Top rail for grip and support
- Nosing: Projecting edge of tread (typically 16-20mm overhang)
- Carriage: Central supporting beam (for wider stairs)
Staircase Planning Tips
Before You Start
- Measure accurately: Floor-to-floor height is critical - measure at multiple points
- Check Building Control: New or significantly altered stairs require approval
- Consider traffic flow: Where will the staircase land? Is there enough circulation space?
- Plan for headroom: Check ceiling heights, beams, and floor joists
- Account for finishes: Floor coverings affect finished height measurements
Common Mistakes to Avoid
Critical Errors
- Inconsistent rise heights: All risers must be the same height (within 5mm tolerance)
- Inadequate headroom: Minimum 2000mm must be maintained throughout
- Wrong 2R + G calculation: Outside 550-700mm range causes discomfort
- Insufficient landing space: Minimum landing length equal to stair width
- Winder errors: Going must be measured at correct position (270mm from narrow end)
Professional Installation vs DIY
While flat-pack staircases are available for DIY installation, there are important considerations:
| Factor | DIY Installation | Professional Installation |
|---|---|---|
| Cost | £500 - £2,000 (kit only) | £2,000 - £8,000+ (supply & fit) |
| Time | 1-3 days (experienced DIYer) | 1-2 days (professional team) |
| Building Regs | You arrange Building Control | Often included in service |
| Guarantee | Materials only | Labour and materials |
| Best for | Simple replacements | New builds, alterations, complex designs |
Frequently Asked Questions
For maximum comfort, aim for a rise of 170-190mm and going of 240-260mm. This gives a 2R + G value of around 600mm, which research shows is the most comfortable for average adult step length. Steeper stairs (higher rise, shorter going) are acceptable under Building Regulations but may be less comfortable for daily use.
Yes, any new staircase or significant alteration to an existing staircase requires Building Control approval. This includes loft conversions, extensions, and like-for-like replacements if the design changes significantly. You can apply directly to your local authority Building Control or use an Approved Inspector. The inspection typically checks rise/going dimensions, headroom, handrails, and guarding.
Measure the floor-to-floor height from finished floor level to finished loft floor level. Divide by your target rise (typically 200-220mm for loft stairs) to get the number of risers. Subtract one for the number of treads, then multiply by your going to find total horizontal space needed. For tight spaces, consider quarter-turn stairs with winders or alternating tread designs (subject to Building Control approval).
Building Regulations require a minimum headroom of 2000mm (2 metres) measured vertically above the pitch line throughout the length of the staircase. For loft conversions in existing dwellings, this can be reduced to 1900mm on the centreline and 1800mm at the edges where headroom is restricted by the roof slope. These relaxations require Building Control approval.
Yes, open riser stairs are permitted but must comply with additional safety requirements. The gap between treads must not allow a 100mm sphere to pass through (child safety). This typically means a maximum gap of 100mm. Open risers are popular in contemporary designs but may not be suitable for homes with young children or where stair safety is a concern.
Building Regulations do not specify a maximum number of steps before a landing for domestic private stairs. However, for common stairs in buildings containing flats, a landing is required after every 16 risers (or 36 risers if the stair serves no dwelling). Landings must be at least as long as the narrowest stair width. In practice, most domestic stairs have 13-15 risers per flight.
Rise is the vertical height of each step (measured from tread to tread). Going is the horizontal depth of each tread (measured nosing to nosing). Together, these dimensions determine the pitch angle and comfort of your staircase. All risers must be the same height, and all goings must be the same depth within a flight (within 5mm tolerance under Building Regulations).
UK staircase costs vary significantly by design and materials. Budget softwood stairs start around £1,500-3,000 supply and fit. Mid-range oak or contemporary designs typically cost £4,000-8,000. Premium bespoke staircases with glass, metal, or exotic timbers can exceed £15,000-30,000. Always get 3+ quotes and ensure the price includes Building Control liaison and completion certificate.
Pro Tips for Accurate Results
- Double-check your input values before calculating
- Use the correct unit format (metric or imperial)
- For complex calculations, break them into smaller steps
- Bookmark this page for quick future access
Understanding Your Results
Our Stairs Calculator provides:
- Instant calculations - Results appear immediately
- Accurate formulas - Based on official UK standards
- Clear explanations - Understand how results are derived
- 2025/26 updated - Using current rates and regulations
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