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Stair and rafter calculator

Work out risers, treads and stringer length, or common rafter length from run and pitch.

Updated: Oct 2026.

For learning only. Check your code book. These calculators are study aids, not design tools. Always follow the code that applies where you work, the manufacturer's instructions and your supervisor. Nothing you type is sent to us or anyone else. Stair and roof limits differ by province and territory; check the building code adopted where you work.

Stairs

Enter the total rise (finished floor to finished floor), the maximum riser height and the tread run you want to use. Take the maximum riser and minimum run from your building code.

Common rafter

Enter the run (half the span, measured level) and the pitch as rise per 12 units of run, for example 6 for a 6/12 roof.

The National Research Council publishes the National Building Code of Canada, which you can download free; provinces and territories adopt their own editions, so ask your local building official which one applies. Studying for carpentry? See the Carpenter guide and our free practice sample.

Sources

  1. National Research Council Canada — National Building Code of Canada 2020 (opens in a new tab)

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