STAIR BUILDER CALCULATOR

---

This Stair Builder Calculator is designed to take the guesswork out of stair layout. You enter the floor-to-floor rise and, if you want, a target riser height or preferred tread depth. The calculator then finds a layout that fits within your chosen limits and shows you the number of risers, riser height, tread count, tread depth, total run, stair angle, and stringer length. The defaults follow common Canadian residential guidelines, but all limits are editable so you can match your local code or project requirements.

Instead of juggling a notepad, tape measure, and half-remembered code numbers, the tool does the math for you. It looks for an integer number of risers that divides the total rise into a comfortable step height, checks that it falls between your minimum and maximum riser values, and then suggests a tread depth using either your preferred value or the classic comfort rule (2R + T within a target range). You can also choose how to count treads – either treads = risers − 1 (top tread is the upper floor) or treads = risers (separate top nosing), which matches how you actually build and frame your stair.

1. Choose units and rounding
    
   • Pick millimetres or inches in the Units field.
      
   • Select a rounding option (e.g., nearest 5 mm or 1/8 in). This rounding is applied to the calculated riser height and tread depth, so you end up with numbers you can actually mark and cut on site.
      

1. Enter your main inputs
    
   • Type the Total Rise (floor-to-floor).
      
   • Optionally enter a Target Riser height if you have a preferred step height.
      
   • Optionally enter a Preferred Tread Depth. If you leave it blank, the calculator suggests a tread using the comfort rule range (2R + T).
      
   • Choose the Treads Count Convention:
      
     • Treads = risers − 1 if your top tread is the finished upper floor, or
        
     • Treads = risers if you’re framing a separate top nosing.
        

1. Check or adjust limits
   Open the Limits & Code Checks section and confirm the defaults:
    
   • Riser Min / Max (e.g., 125–200 mm)
      
   • Tread Min / Max (effective depth)
      
   • Comfort Rule Low / High (2R + T range)
     You can tweak these to match local building code or specific project requirements.
      

1. Review the results
   The Results panel shows:
    
   • Risers and Riser Height
      
   • Treads and Tread Depth
      
   • Total Run of the stair
      
   • Stair Angle (in degrees)
      
   • Stringer Length (hypotenuse of rise vs run)
     Along with that, the Checks area can highlight whether the layout stays within your riser, tread, and comfort rule limits.
      

Use this tool as a layout helper and sanity check before you start cutting stringers or ordering materials. It won’t replace your local building code or inspector, but it gives you a fast, clear way to design stairs that are comfortable to walk and much more likely to pass inspection.