Stair stringer and riser calculator

Enter the total rise from finished floor to finished floor, your target riser height, and your tread run. The calculator works out the riser count, the exact riser height every step will share, total run, and stringer slope length, and flags the layout against common Canadian model code limits. Switch between metric and imperial at any time. Your choice is remembered on this device. All results are estimates only.

Calculator

Total rise, finished floor to finished floor (m)

Target riser height (mm)

Tread run, nosing to nosing (mm)

Formulas: risers = ceiling of (total rise / target riser height), epsilon safe. Actual riser height = total rise / risers, so every riser is identical. Treads = risers minus 1, because the upper floor is the last tread surface. Total run = treads x tread run. Stringer slope length = square root of (total run squared + total rise squared), an approximation of the cut stringer slope before end cuts and layout allowance. Code check applied: riser at most 200 mm, riser at least 125 mm, tread run at least 255 mm, the National Building Code of Canada model limits for many residential stairs. Your province or territory may set different limits.

Worked example: Total rise 2400 mm, target riser 180 mm, tread run 280 mm. Risers = 2400 / 180 = 13.33, rounded up to 14 risers. Actual riser height = 2400 / 14 = 171.4 mm (6.75 in). Treads = 14 minus 1 = 13. Total run = 13 x 280 = 3640 mm (11.94 ft). Stringer slope length = square root of (3640 squared + 2400 squared) = square root of 19,009,600 = 4360 mm (14.30 ft). Code check: riser 171.4 mm is at most 200 mm and at least 125 mm, and run 280 mm is at least 255 mm, so this layout passes the model limits used here.

Estimates only. This is a planning check against model code limits, not a code compliance certification and not engineering advice. Headroom, guards, handrails, stair width, and landings are not calculated here. Verify the full design against your provincial or territorial code and with a qualified professional before cutting stringers.

Frequently asked questions

What riser and tread sizes are typical in Canada?

The National Building Code of Canada model limits for many residential stairs are a riser height of at most 200 mm and a tread run of at least 255 mm, with a riser minimum of 125 mm. Provincial and territorial codes adopt or amend the model code, so your local numbers can differ. The calculator flags your layout against the model limits as a planning check only.

Why is the stringer longer than the slope distance shown?

The slope distance is the straight line from the first tread nosing to the top of the rise. A real stringer needs extra stock for the top and bottom cuts, the heel, and layout marks. Buy stringer stock longer than the slope distance and confirm the length against your layout before cutting.

Back to all BuildTrue estimators, including concrete, drywall, deck, framing, and the bid helper