Stair Calculator
Calculate stair rise, run, number of steps, stringer length, stringer height, stair angle and optional headroom requirements.
Basic Stair Calculator
Use one fixed run or enter a total run. The calculator evaluates practical riser counts and shows the resulting stair geometry.
Comprehensive Stair Calculator
Build a more complete stair layout using fixed rise or fixed number of steps, tread thickness, headroom and stringer mount options.
Fraction to Decimal Conversion
Common stair measurements are often entered as fractional inches. Use this table to convert common fractions to decimals.
| 16ths | 8ths | 4ths | 2nds | Decimal |
|---|---|---|---|---|
| 1/16 | 0.0625 | |||
| 2/16 | 1/8 | 0.125 | ||
| 3/16 | 0.1875 | |||
| 4/16 | 2/8 | 1/4 | 0.25 | |
| 5/16 | 0.3125 | |||
| 6/16 | 3/8 | 0.375 | ||
| 7/16 | 0.4375 | |||
| 8/16 | 4/8 | 2/4 | 1/2 | 0.5 |
| 9/16 | 0.5625 | |||
| 10/16 | 5/8 | 0.625 | ||
| 11/16 | 0.6875 | |||
| 12/16 | 6/8 | 3/4 | 0.75 | |
| 13/16 | 0.8125 | |||
| 14/16 | 7/8 | 0.875 | ||
| 15/16 | 0.9375 | |||
| 16/16 | 8/8 | 4/4 | 2/2 | 1 |
Stair Geometry
Rise is the vertical step height and run is the horizontal tread depth. Stringer length follows the sloped line of the stair. Local building codes may impose additional requirements for riser height, tread depth, handrails, guards and headroom.
How to Use the Stair Calculator
- Choose Basic or Comprehensive mode.
- Enter the total rise and either one run or the total run.
- In Comprehensive mode, choose a fixed rise or fixed number of steps.
- Optionally enter tread thickness and headroom requirements.
- Click Calculate Stairs to see the complete stair dimensions.
Frequently Asked Questions (FAQs)
It calculates stair rise, run or tread, number of risers and runs, total run, stringer length, stringer height, stair angle and optional headroom and floor-opening checks.
The riser is the vertical height between consecutive treads. The tread or run is the horizontal distance available for each step.
The number depends on the total rise and the selected riser height. Basic mode evaluates practical integer riser counts, while Comprehensive mode can use a fixed rise or fixed number of steps.
Stringer length is the sloped structural length of the stair, calculated from the horizontal run and the effective vertical stringer height.
Headroom requirements vary by local building code. The calculator can check a user-specified minimum headroom against the stair geometry; always verify the final design against the applicable local code.