Stair Material Calculator
Generate your complete lumber yard shopping list: stringer boards, tread material, risers, Simpson brackets, and structural screws.
Input Dimensions
Stringer Results
Enter dimensions and click Calculate Stringer to see results.
Interactive Cut Stringer Blueprint
Standard Staircase Worked Examples
Click any preset to automatically populate the calculator with proven dimensional specifications.
How to Calculate Lumber Waste and Takeoffs
Best practices for ordering dimensional lumber and estimating fastener quantities.
Measure Total Rise
Measure the exact vertical distance between finished floor surfaces using a plumb bob or laser level. Always account for finished flooring thickness.
Calculate Number of Steps
Divide total rise by your target riser height (typically 7.5"). Round to the nearest whole integer to find the exact number of equal risers.
Determine Riser & Run
Divide total rise by the number of risers for exact height. Select tread depth (minimum 10") and verify with Blondel’s comfort formula (2R + T = 24–25").
Layout & Deduct Bottom Foot
Step off cuts with a framing square and stair gauges. Deduct the thickness of one tread from the bottom cut so the finished first step matches the rest.
Hardware, Fastener & Lumber Takeoff Guide
Recommended screw types, bracket schedules, and dimensional lumber lengths.
Building Code Comparison (IRC vs IBC vs OBC vs UK)
| Code Authority | Max Riser | Min Tread | Min Width | Min Throat |
|---|---|---|---|---|
| IRC Residential (US) | 7.75" (196 mm) | 10.0" (254 mm) | 36" (914 mm) | 3.5" (89 mm) |
| IBC Commercial (US) | 7.00" (178 mm) | 11.0" (279 mm) | 44" (1118 mm) | 3.5" (89 mm) |
| OBC (Ontario, Canada) | 8.25" (210 mm) | 8.25" (210 mm) | 33.5" (860 mm) | 3.5" (89 mm) |
| UK Approved Doc K | 8.66" (220 mm) | 8.66" (220 mm) | 31.5" (800 mm) | 3.5" (89 mm) |
Lumber Selection vs Notch & Throat Depth
| Nominal Size | Actual Width | Max Cut Notch | Remaining Throat | Recommendation |
|---|---|---|---|---|
| 2×8 | 7.25" (184 mm) | 4.50" | 2.75" (Deficient) | Not Code Compliant |
| 2×10 | 9.25" (235 mm) | 5.75" | 3.50" (Borderline) | Shallow stairs only |
| 2×12 | 11.25" (286 mm) | 6.25" | 5.00" (Excellent) | Standard / Best Choice |
| LVL / Engineered | 11.875" (302 mm) | 6.50" | 5.375" (Super-Duty) | Heavy Commercial / Long Spans |
Stair Material Takeoff FAQs
Answers to common questions regarding lumber ordering and fastener selection.
What fasteners should I use to mount stair treads to stringers?
Use 2-1/2" to 3" exterior-grade structural wood screws or stainless steel screws. When working with composite decking treads, use manufacturer-approved composite screws with reverse threads to prevent mushrooming.
How do I calculate total linear feet of lumber for my stairs?
Add the total length of all stringer boards plus the total length of all tread planks (stair width × number of treads) and riser boards (stair width × number of risers). Add 15% for cuts and end trimming.