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Stair Calculator
Calculate stair surface area
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Result
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What this calculator does
Calculates the surface of a flight of stairs, treads plus risers, for covering such as carpet, paint or cladding.
How to use it
- Enter the number of steps and stair width.
- Enter tread depth and riser height in centimeters.
- Set waste for cuts and read the area.
Formula
Area m² = Number of Steps × Stair Width × (Tread Depth + Riser Height)/100 × (1 + Waste Margin (%) / 100)
Formulas are shown in metric units, exactly as the calculator computes them. Imperial entries are converted to metric first. Waste is applied as a multiplier (1 + waste/100).
Areas are in m² and volumes in m³. Centimeters are divided by 100 to give meters.
Variables
| Variable | Unit | Default |
|---|---|---|
| Number of Steps | - | 12 |
| Stair Width | m | 0.9 |
| Tread Depth | cm | 28 |
| Riser Height | cm | 18 |
| Waste Margin (%) | % | 10 |
Worked example
Using the default values of this calculator (Number of Steps = 12, Stair Width = 0.9 m, Tread Depth = 28 cm, Riser Height = 18 cm, Waste Margin (%) = 10 %), the calculator returns:
Area m² = 12 × 0.9 × (28 + 18)/100 × (1 + 10 / 100)
- Total Stair Area: 5.465 m²
Assumptions and limitations
- Only tread plus riser covering area is computed: this is not a stair safety or geometry check.
- Nosings, stringers, landings and winders are ignored.
Waste, rounding and buying
Stair coverings waste more because of edge cuts; round up and measure on site.
Frequently asked questions
- Does it check if my stairs are safe?
- No. Tread and riser limits come from building rules; this tool only totals surface area.
- Are landings included?
- No. Calculate landings as floor areas.