Stairs are safety-critical. Measure from finished landing to finished deck surface, then verify current local rules for rise, tread, uniformity, width, landings, headroom, guards, handrails, nosings, stringers, connections, and foundations.
01 / Formula
How this is calculated
Risers = ceiling(total rise ÷ verified maximum riser); actual rise = total rise ÷ risers; projected run = treads × tread depth02 / Assumptions
What the estimate assumes
- ✓Total rise uses finished elevations.
- ✓The maximum riser and tread depth are user-entered verified criteria.
- ✓The calculation is a layout check, not a stringer or connection design.
03 / Worked example
See the math in context
A 42-in total rise with a 7.75-in entered maximum needs 6 equal 7-in risers and 5 treads.
04 / Guidance
Recalculate after finishes
Decking, landing, and tread thicknesses affect finished elevations and stringer layout. Field-verify before cutting all stringers.
05 / Guidance
Check the entire stair
A compliant rise/run pair does not establish compliant width, landings, headroom, handrails, guards, openings, illumination, foundations, or connections.
Questions
Frequently asked
Are the calculator defaults building-code requirements?+
No. They are editable planning inputs. Verify current local code, approved plans, span tables, product evaluation reports, and manufacturer instructions before construction.
Does the estimate include the complete deck structure?+
Only if every component is explicitly listed. Footings, posts, beams, ledgers, flashing, lateral connections, guards, stairs, hardware, fascia, permits, delivery, and waste often require separate takeoffs.
How should I measure a non-rectangular deck?+
Divide the surface into rectangles and other measurable shapes, calculate each separately, then account for board direction, seams, breaker boards, borders, stairs, and reusable offcuts.
Sources