Stair Stringer Length Calculator

Plan stair framing by combining total rise, target riser height, and tread depth. The calculator estimates overall stringer length, recalculates the final riser height, and reports total horizontal run so you can lay out cuts before marking your stock.

Vertical distance from finished lower floor to finished upper floor measured in metres.
Target rise per step—check local code; 0.18 m ≈ 7.1 in.
Horizontal run per step measured nose to nose; 0.26 m ≈ 10.25 in.

For planning purposes; check local building codes for compliance.

Examples

  • Total rise 2.80 m, riser 0.18 m, tread 0.26 m ⇒ 4.93 m stringer | 16 steps at 175 mm rise | Total run 4.16 m.
  • Total rise 1.50 m, riser 0.175 m, tread 0.25 m ⇒ 2.75 m stringer | 9 steps at 167 mm rise | Run 2.25 m.
  • Basement stairs: rise 2.35 m, riser 0.19 m, tread 0.24 m ⇒ 4.02 m stringer | 13 steps at 181 mm rise | Run 3.12 m.
  • Deck stairs: rise 0.90 m, riser 0.18 m, tread 0.28 m ⇒ 1.68 m stringer | 5 steps at 180 mm rise | Run 1.40 m.

FAQ

Why is step count rounded up?

Rounding up ensures the total rise is fully covered. The actual riser height per step is recalculated so each rise is identical.

Can I use inches instead of meters?

Yes—convert inches to metres (divide by 39.37) or, alternatively, enter all dimensions in inches and multiply the final stringer result by 39.37 to convert back. Consistency matters most.

Does it account for nosing?

No. Include nosing, finish flooring thickness, or landing recesses manually when marking your stringer stock.

How many stringers do I need?

Most residential stairs use two outer stringers and a centre support when the run exceeds 36 in. Use the calculated step count to align additional stringers.

Additional Information

  • Stringer length is measured along the slope from the first tread cut to the upper landing—add extra material for overhangs or notches.
  • The calculator rounds the step count up to ensure the total rise is met; actual riser height is recalculated for a consistent flight.
  • Verify tread depth and riser height against local building codes (for example, maximum riser 7.75 in. and minimum tread 10 in. in many jurisdictions).
  • Lay out the stringer with a framing square and stair gauges; mark the level cut at the top and plumb cut at the bottom before cutting.
  • For open-stringer designs, add tread overhang and trim thickness to the calculated run before cutting stock.

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