Measuring a jobsite stair before you calculate
A temporary construction stair gets rebuilt or moved as the job progresses, so re-measuring quickly matters more here than on a finished house stair.
Find your total rise
Measure straight down from the platform, deck edge, or floor level the stair needs to reach, to the grade or lower level it starts from. On a footing or foundation stair this is usually the excavation depth to the top of the wall or slab.
Note your available run
Measure the horizontal space you actually have at the base — trench width, lay-down area, or distance to the excavation edge. This tells the calculator whether the stair will physically fit before you cut stringers.
Pick a target riser, or leave it on Auto
Leave it on Auto for a 7" target, which keeps the finished angle safely inside OSHA's 30°–50° window. If the job has a fixed riser requirement — matching an existing partial stair, for example — switch to Custom.
Read the compliance chips
Green means the result sits inside 29 CFR 1926.1052 limits for angle, landings and riser uniformity. Red or neutral chips flag something to check — total rise past 144" always needs a landing, and four or more risers always needs a handrail.
The five formulas behind every result
Nothing on this page is a black box. Here's exactly what runs when you change a number.
Step Count
Total rise divided by your target riser height, rounded to the nearest whole step — you can't build a fractional stair.
Actual Riser Height
The rounding above means your real riser is rarely the exact target. This is the number every riser gets built to, uniformly, within OSHA's ¼" variance tolerance.
Auto Tread Depth
Instead of a fixed comfort ratio, tread depth is solved backward from your target angle (35° by default) — 1926.1052 governs angle directly, not tread depth.
Stair Angle & Stringer
Angle from the actual riser-to-tread ratio; stringer length from the Pythagorean triangle formed by total rise and total run.
Flights & Landings
OSHA caps a single flight of a non-permanent stairway at 144" (12 ft) of vertical rise before a landing is required — a different number from the IRC's 147", see the comparison table below.
Walking through a real 96" rise
Same five formulas, filled in step by step, for a foundation-to-grade access stair climbing 8 feet (96") — the default this calculator loads with.
Step count
96" total rise, targeting a 7" riser: 96 ÷ 7 = 13.71, which rounds to 14 steps. You can't cut a fractional step, so the calculator always rounds to the nearest whole number here.
Actual riser height
Re-divide the total rise by that whole step count: 96 ÷ 14 = 6.86" per riser. That's the number every riser gets built to — not the 7" target, which was only a starting point. Note this is already comfortably below any residential code max, though 1926.1052 itself sets no such max.
Auto tread depth
Solving backward from the 35° target angle: 6.86 ÷ tan(35°) = 6.86 ÷ 0.700 = 9.80". This is the formula card's key interaction — the rounded step count from step 1 changed the actual riser, which changes the auto tread here, even though you never touched the tread field.
Run, angle, and stringer
13 treads (one fewer than the step count) at 9.80" each gives a total run of 127.4". Because tread was solved from the 35° target, the resulting angle checks out almost exactly at 35.0° — dead center of OSHA's 30°–50° range. Stringer length is √(96² + 127.4²) ≈ 159.5", the board length a stringer has to be cut from before notching.
This flight also stays under the 144" landing trigger, so no intermediate landing is needed — but with 14 risers, well past the 4-riser threshold, a stairrail and handrail are required on the open side regardless of how comfortable the angle is. Angle compliance and handrail compliance are two separate checks, and it's easy to satisfy one while forgetting the other.
OSHA construction stairs vs. residential IRC stairs
This is the single most common source of error on jobsite stairs: applying the finished-house rulebook to a stair that's governed by a completely different one. The numbers genuinely differ — here's why.
| Requirement | OSHA Construction — 1926.1052 (this tool) | IRC Residential (permanent, finished stairs) | OSHA General Industry — 1910.25 (permanent workplace stairs) |
|---|---|---|---|
| Applies to | Temporary, job-site access stairs during construction | Finished dwelling interior/exterior stairs | Permanent stairs in an existing workplace |
| Max riser height | No fixed max — uniform within ±¼" | 7.75"–8.25" (edition-dependent) | 9.5" |
| Min tread depth | No fixed min — uniform within ±¼" | 9"–10" (edition-dependent) | 9.5" |
| Allowed stair angle | 30°–50° | No hard cap (comfort target ~30–37°) | 30°–50° |
| Max single-flight rise before landing | 144" (12 ft) | 147" (12'-3") | [VERIFY: confirm 1910.25 max flight rise before a landing is required] |
| Handrail required at | 4+ risers or rise >30" | 4+ risers | [VERIFY: confirm 1910.25 handrail-required riser threshold] |
| Handrail height | 30"–37" | 34"–38" | [VERIFY: confirm 1910.25 handrail height range] |
This calculator's live checks use the OSHA Construction (1926.1052) column only, because that's the standard that governs a non-permanent access stair while a job is underway. Once a stair becomes a permanent part of the finished structure, it needs to be re-checked against IRC or 1910.25 as applicable — that's what the Stair Rise and Run Calculator and IRC Stair Code Checker are for.
OSHA 1926.1052, quick reference
This calculator checks your result against the limits below. Full stairrail and handrail construction details (grip size, clearance, surfacing) are covered by 1926.1052(c) but aren't reproduced here.
| Element | Requirement | Citation |
|---|---|---|
| Stair angle | 30°–50° from horizontal | 1926.1052(a)(2) |
| Riser/tread uniformity | ±¼" max variation, whole flight | 1926.1052(a)(3) |
| Landing (non-permanent stair) | Min. 30" deep × 22" wide, every ≤144" rise | 1926.1052(a)(1) |
| Door/gate swing platform | Min. 20" effective width | 1926.1052(a)(4) |
| Handrail/stairrail trigger | 4+ risers or rise >30" (whichever is less) | 1926.1052(c)(1) |
| Handrail height | 30"–37" above tread nosing | 1926.1052(c)(6) |
| Temporary treads (metal pan/skeleton) | Wood or solid material, full width & depth | 1926.1052(b)(2)–(3) |
Reference only — always confirm against the current edition of 29 CFR 1926.1052 and your site-specific safety plan before building.
Landings, handrails & when you even need a stairway
A temp stair can pass every riser and angle check and still be a citation waiting to happen — this section covers the three things most often missed on a moving jobsite.
When you need a landing
OSHA caps a single flight of a non-permanent stairway at 144" (12 ft) of vertical rise. This calculator's Landings Needed result flags it automatically — an 8-ft foundation stair never triggers it, but a full two-story temporary access run often does. Each landing needs to be at least 30" deep in the direction of travel and 22" wide.
When you need a stairway at all
Below that threshold a single step or curb is generally acceptable; above it, OSHA expects a stairway, ramp or ladder providing safe access. Confirm the exact figure and any site-specific safety plan requirements before relying on a single step.
Handrail & stairrail trigger
Whichever threshold is hit first triggers the requirement — a short, steep run of 3 risers rising 32" still needs a stairrail even though it's under 4 steps. This calculator checks both conditions, not just step count.
Metal pan & skeleton stairs
If permanent pan or skeleton stairs are being built but not yet filled or decked, foot traffic is prohibited unless secured temporary treads cover the entire tread and landing area. This is one of the more commonly skipped steps on a fast-moving structural steel job.
These are planning-stage estimates, not a substitute for your site's competent-person sign-off. A stair carrying material loads, wheelbarrows, or an unusual span may need engineering review regardless of what this calculator shows.
Common mistakes when planning a temporary jobsite stair
Most OSHA stairway citations trace back to one of these five planning errors, not to bad carpentry.
Designing to IRC riser/tread limits instead of OSHA's angle rule
1926.1052 doesn't set a max riser or min tread for a temp stair — it sets an angle range and a ¼" uniformity rule. A stair built to IRC's 7.75"/10" numbers can still fail the angle check if the tread is skimped.
Building a steeper stair to save floor space
Once the angle passes 50°, the stair is out of compliance regardless of how solid the build is — a common shortcut on a tight excavation or a rushed re-decking, and one of the fastest ways to draw a citation.
Forgetting the landing past 144" of rise
Multi-story temporary access stairs commonly cross this threshold. The IRC's 147" figure gets misapplied here — the OSHA number for a non-permanent stairway is 3" tighter.
Skipping the handrail at exactly 4 risers
Crews often treat "small stair, no rail needed" as a judgment call. It isn't — 4 risers or 30" of rise (whichever comes first) is a hard trigger, not a suggestion.
Leaving metal pan treads unfilled and untraveled-on unsafely
Foot traffic on pan or skeleton stairs before the treads are filled or fitted with secured temporary decking is a frequent fall hazard on structural steel and concrete jobs moving fast toward topping-out.
Not re-checking the stair after it gets rebuilt
Temporary stairs get relocated, extended, or rebuilt as excavation depth or deck height changes through the job. Each rebuild is a new stair for compliance purposes — re-run the numbers, don't assume the old riser height still works.
When to use a temporary construction stair calculator
Temporary access stairs go up and come down constantly as a job progresses — this shows up at nearly every phase.
Foundation & Excavation Access
Getting crews safely from grade down into a foundation trench or basement excavation.
Multi-Story Framing
Floor-to-floor access before permanent stairs are framed and installed.
Scaffold & Formwork Platforms
Access to elevated pour decks, formwork platforms, or scaffold levels.
Trench & Pit Access
Civil and utility sites needing safe egress from a trench or excavation pit.
Phased Renovation Egress
Maintaining safe access in an occupied or partially-demolished building mid-renovation.
Demolition Site Access
Getting crews to and from working levels as a structure is progressively removed.