SettingsSettings for this calculationUS
The whole height the steps climb, from the lower level to the upper.
Finished level to finished level. The page divides it into equal steps, which is what makes the rise consistent throughout the flight.
The steps are made no taller than this, in as few equal steps as that allows.
Approved Document M asks for a rise between 150 and 170 mm (about 5⅞ to 6¾ in) on external steps, and prefers 150 mm (about 5⅞ in) for schools. A lower rise needs more steps and more length.
The depth of each tread, nosing to nosing.
Approved Document M asks for 280 to 425 mm (about 11 to 16¾ in). A going of 350 mm (about 13¾ in) or more lets a flight have 18 risers instead of 12.
Risers in the stepped approach
6 risers
The rise divides into 6 equal steps in 1 flight of no more than 12 risers each. Each step's rise is within the range Approved Document M gives, and its going is within its range. Being inside the ranges is not a finding that the steps are safe to use: the nosings, handrails, hazard-warning surface, width and landings each have their own requirement.
- Rise of each step
- 6 in
- Lowest rise Approved Document M gives for external steps
- 5.91 in
- Highest rise it gives
- 6.69 in
- Going of each step
- 11.75 in
- Most risers in one flight at this going
- 12 risers
- Flights
- 1 flight
- Treads
- 5 treads
- Level landings, top, bottom and between
- 2 landings
- Each landing, at least
- 3.94 ft
- Horizontal length, landings included
- 12.77 ft
They open the calculator with your figures already in it
External Stepped Access Calculator (Approved Document M): 6 risers — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- Approved Document M Volume 2, para 1.33: the rise of each step between 150 mm and 170 mm and the going between 280 mm and 425 mm, consistent throughout a flight; no more than 12 risers in a flight for a going under 350 mm and no more than 18 for a going of 350 mm or more; a level landing at the top and bottom of each flight at least 1200 mm long; no single steps; flights at least 1.2 m wide; no open risers; contrasting nosings 55 mm wide; handrails on both sides
Inputs used
- Total Rise of the Approach
- 3 ft
- Largest Step Rise You Want
- 6.25 in
- Going of Each Step
- 11.75 in
Intermediate steps
- Rise of each step
- 6 in
- Lowest rise Approved Document M gives for external steps
- 5.91 in
- Highest rise it gives
- 6.69 in
- Going of each step
- 11.75 in
- Most risers in one flight at this going
- 12 risers
- Flights
- 1 flight
- Treads
- 5 treads
- Level landings, top, bottom and between
- 2 landings
- Each landing, at least
- 3.94 ft
- Horizontal length, landings included
- 12.77 ft
Confidence note: The rise divides into 6 equal steps in 1 flight of no more than 12 risers each. Each step's rise is within the range Approved Document M gives, and its going is within its range. Being inside the ranges is not a finding that the steps are safe to use: the nosings, handrails, hazard-warning surface, width and landings each have their own requirement.
What this calculation does not cover
- Straight flights with landings of the minimum length. A landing where the steps turn, or where a door opens onto it, needs more room.
- External steps only. Internal stairs in buildings other than dwellings follow Approved Document K's rules for a general access stair, and have their own calculator on this site.
- It does not check the nosings, the hazard-warning surface, the handrails, the width or whether the rises are closed — all separate requirements of the same paragraph.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-22 · v1.0.0
Regulatory standards & verification citations1
- Approved Document M Volume 2, para 1.33: the rise of each step between 150 mm and 170 mm and the going between 280 mm and 425 mm, consistent throughout a flight; no more than 12 risers in a flight for a going under 350 mm and no more than 18 for a going of 350 mm or more; a level landing at the top and bottom of each flight at least 1200 mm long; no single steps; flights at least 1.2 m wide; no open risers; contrasting nosings 55 mm wide; handrails on both sides
Which documents these citations point at
- Approved Documents to the Building Regulations (England) — M (United Kingdom)Practical guidance on meeting the Building Regulations, one lettered part per subject — Part A structure, Part B fire, Part K protection from falling, Part L conservation of fuel and power, and the rest.
A code or standard has force only where a jurisdiction has adopted it, usually with local amendments. This site holds no adoption data for any authority, so check what is in force with the authority where you build. Any section cited above without an edition should be checked against the edition in force where you build. What it would take to know.
Cite this page
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