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When designing or redesigning a set of stairs there can often be some confusion with regards to number of stairs, height and length of stair. Often you need to sit down and really think about the design to ensure that everything fits and is up to standard! We recommend undertaking a thorough measured survey of the area to ensure everything you are designing will fit!
Using our free stair calculator below you will be able to work out:
- The number of risers and goings
- The individual rise and going
- The pitch (elevation angle, in degrees)
- Whether the stair meets the rise, going and pitch limits in Approved Document K
There is also a quick compliance checker if you already have a rise and going in mind.
Terminology Diagram
Stair Calculator Terminology
Elevation Angle
Angle of stairs from horizontal in degrees.
O/A Rise Length
Overall vertical distance between floor levels.
O/A Run Length
Overall horizontal distance between start and end of the stair.
Rise Length
Vertical distance between the stair and next stair.
Run / Going
Horizontal distance from the end of the previous stair and start of next.
Stair rise and going calculator
Stair rise and going calculator
Work out the optimal number of steps, rise and going for your stair, and check it against Approved Document K.
Total floor-to-floor rise.
Total horizontal space available.
Leave blank to let the calculator pick this for you.
Leave blank to let the calculator pick this for you.
Fill in height + length for the fully optimised result, or height (or length) + a desired rise or going to fix one dimension and find the best match for the rest. Height on its own works out the minimum length needed for a compliant stair; length on its own works out the maximum height a single flight can serve.
Quick compliance checker
Already have a rise and going in mind? Check it directly against the legal tolerances.
About these figures
Figures are taken from Table 1.1 (rise and going) of Approved Document K, Building Regulations 2010, 2013 edition incorporating the 2013 and 2015 amendments, which applies in England.
This tool gives guidance only and does not replace sign-off from a building control body, architect or structural engineer. Always confirm final dimensions with Building Control before construction.
| Category | Rise | Going | Max pitch |
|---|---|---|---|
| Private stair | 150 to 220mm | 220 to 300mm | 42° |
| Utility stair | 150 to 190mm | 250 to 400mm | n/a |
| General access stair | 150 to 170mm | 250 to 400mm | n/a |
All categories must also satisfy: twice the rise plus the going (2R + G) is between 550mm and 700mm. For school buildings the preferred going is 280mm and the preferred rise 150mm.
Stair Standards
The current standards document is Approved Document K, 2013 edition incorporating the 2013 and 2015 amendments. The calculator above uses its Table 1.1 figures. This can be found here.
Please double check the information for yourself before you commit to any designs!
Private Stairs
Min Rise (mm) = 150 mm
Max Rise (mm) = 220 mm
Min Going (mm) = 220 mm
Max Going (mm) = 300 mm
Utility Stairs
Min Rise (mm) = 150 mm
Max Rise (mm) = 190 mm
Min Going (mm) = 250 mm
Max Going (mm) = 400 mm
General Access Stairs
Min Rise (mm) = 150 mm
Max Rise (mm) = 170 mm
Min Going (mm) = 250 mm
Max Going (mm) = 400 mm
Max Elevation Angle = 42º
Other Requirements:
- For school buildings, the preferred rise is 150 mm and the preferred going is 280 mm.
- For dwellings, for external tapered stairs that are part of the buildings, the going should be a minimum of 280 mm.
- For existing buildings, alternatives may be proposed if the dimensional constraints do not allow these requirements to be followed.
- There are more complex requirements for stepped gangways in assembly buildings, and there may be a conflict between these requirements and sightlines in some buildings with spectator seating.
- Buildings that are not dwellings and common areas in buildings that contain flats should not have an open riser, should have visual contrast to make nosings apparent, and nosings should not protrude by more than 25 mm.
- The minimum headroom should be 2 m.