Tile quantities
Stair tread and riser tiling area and nosings
- where
- tread area (m²)
- number of treads
- stair width (m)
- tread depth including nosing (mm)
- riser area (m²)
- number of risers
- riser height (mm)
- total area (m²)
- landing area (m²)
- nosing trim length (m)
Explain this equation
Works out the area of tiling on a flight of stairs and the length of stair nosing trim to buy.
nt is the number of treads and nr the number of risers. Ws is the stair width, G the tread depth including the nosing and R the riser height. At and Ar are the tread and riser areas; the 1000 converts millimetres to metres. A adds the landing Al. Ln is the length of nosing, one per tread across the width.
Each tread and riser is a rectangle, so the area is count times width times depth. A straight flight usually has one more riser than treads, because the top landing acts as the last step.
Sense check: 12 treads 250 mm deep and 13 risers 200 mm high on a 900 mm wide stair come to about 5 m² of tiling and 10.8 m of nosing.
Watch out: measure the tread to the front of the nosing, not just the going between steps. Add generous waste, because every tread is cut.
Tiled area of treads, risers and landing, and the length of stair nosing trim.
Enter your values to see the result.
Good to know
A straight flight usually has one more riser than treads, because the top floor or landing acts as the last tread. Measure tread depth to the front of the nosing. Approved Document K limits private stairs to a rise of 150–220 mm and a going of 220–300 mm, which is a useful check on your measurements. Every tread and riser is a cut row, so take the waste from the higher end (15% or more) when converting to tiles.
Common mistake
Using the going (horizontal step-to-step distance) as the tread depth, which misses the nosing overhang on every step.
Limits
Straight flights. Winders and curved stairs need each tread measured as a shape. Anti-slip nosing must suit the tile thickness and adhesive bed.
Sources
Results are calculations from the published methods and manufacturer figures shown, and depend on the data you enter. Always follow the tile, adhesive and grout manufacturers’ instructions, BS 5385 and the Tile Association guidance. Coverage rates vary by product and substrate. Check prices and VAT rules with your own records and HMRC.