Stairs Square Footage Calculator
Get the total surface area of your stairs — treads, risers, stringer sides and the sloped wall — for ordering flooring, paint or tile.
Finished floor to finished floor.
The depth you step on, not counting the nosing.
Sets the tread and riser face area.
How to measure stair area
The square footage of a staircase is not a single flat number — it is the sum of the surfaces you actually need to cover. Which surfaces count depends on what you are buying, so the calculator breaks the total into the parts that matter and adds them up in both square feet and square meters from your step dimensions.
- Tread + riser area — the tops of the treads and the faces of the risers. This is the surface you carpet, tile or refinish. It is the step depth plus the riser height multiplied by the stair width, summed across every step.
- Stringer-side area — the two exposed sawtooth boards running up each side. Use this for painting or cladding the sides of an open flight; it is the stringer length times the board depth, for each stringer.
- Raking-wall area — the sloped triangle of wall alongside the flight. Its area is about half the total run times the total rise. Use it to order drywall, paint or paneling for the wall the stairs run against.
For paint, estimate from the painted surfaces — risers, stringers and the raking wall — at the coverage printed on the can (about 350–400 ft² per gallon), then double it for a second coat. The calculator reports a one-coat gallon estimate alongside the areas, and the 2D elevation shows the exact stair the numbers come from. Covering the treads in carpet instead? The stair carpet calculator works in runner length and yardage, and for a poured stair the concrete stairs calculator gives the volume to order.
Worked example — a 16-step flight
Take the canonical staircase: 16 risers at 7³⁄₁₆″, an 11″ run, 36″ wide, with a 16′‑9″ stringer on each side. Each surface area is computed separately, then summed:
| Surface | Area (ft²) | What it’s for |
|---|---|---|
| Tread + riser faces | 72.7 | Carpet / tile / refinish surface |
| Stringer sides (×2) | 31.4 | Paint or clad an open flight |
| Raking wall | 65.8 | Drywall / paint the sloped wall |
| Total | 169.9 | ≈ 15.8 m² across all surfaces |
At 350 ft² per gallon the 169.9 ft² total takes one gallon for a single coat — what the calculator’s “Paint: 1 gal (1 coat)” tile reports — so order two gallons for the usual two coats. For carpet, tile or refinishing you only cover the walking faces, so the 72.7 ft² tread-and-riser figure is the one to use, not the whole-stair total.
Common square-footage mistakes
- Using the floor footprint. A stair’s plan area badly understates the material needed — every tread, riser and the sloped wall add surface the footprint never sees.
- Forgetting the risers. Carpet and tile wrap the vertical riser face as well as the tread top; counting only treads shorts you nearly half the facing.
- Painting one coat. Bare or previously dark wood needs two coats — double the area before dividing by the can’s coverage.
- Skipping the waste allowance. Tile and laminate need ~10% extra for cuts, breakage and the nosing trim, which the raw surface area does not include.
- Counting closed stringers you can’t see. Only the exposed stringer sides need cladding or paint; a stair boxed in by walls on both sides has no stringer-side area to finish.
Frequently asked questions
How do you calculate the square footage of stairs?
Add up the surfaces you actually need: the tread tops, the riser faces, the two stringer sides, and the sloped (raking) wall alongside the flight. Stairs Calc totals these in square feet or square meters from your step dimensions.
How much paint for a staircase?
Estimate from the painted area — risers, stringers and the raking wall — at the coverage on your paint can (about 350–400 ft² per gallon), then double it for two coats. Stairs Calc reports the area and a gallon estimate.
How do I measure the sloped (raking) wall?
The raking wall is the triangle beside the flight: its area is roughly half the total run times the total rise. Stairs Calc computes it from your rise and run so you can order drywall, paint or paneling.
How much tile or laminate do I need for stairs?
Buy for the tread‑plus‑riser surface — the faces you walk on and see. That is the step depth plus the riser height, multiplied by the stair width, summed over every step; a typical 16‑step, 36″‑wide flight works out to about 73 ft² (6.8 m²) of facing before cuts. Add roughly 10% for cutting waste and breakage, and remember tile needs a bullnose or stair‑nose trim at each nosing, which the square footage total above does not include.
Related stair calculators
Written by the Stairs Calc editorial team. Methodology and code references: see our methodology.
Built and maintained by builders, drafters and engineers who plan stairs for a living — every code limit is transcribed from the published standard and cited to its exact section.
Last reviewed 2026-06-20 against IRC 2021/2024
Stairs Calc gives accurate geometry and checks it against published building-code limits, but results are estimates for planning. Codes are adopted and amended locally and change over time. Always confirm dimensions against your local adopted code and a licensed professional before you build.