Why layout is a separate step from design
Once you know riser height and going from the design stage, laying that out onto a stringer board is a physical, cumulative process: you mark one step, then the next, then the next, and any small error in the first mark repeats and compounds down the whole board. A framing square set to the riser height and going measurements is the standard tool for this in both the UK and US, used exactly the same way on either side of the Atlantic even though the units differ — millimetres on a metric square, inches on an imperial one.
Setting up the framing square
A framing square has two arms, a longer blade (typically 600mm/24in) and a shorter tongue (typically 400mm/16in). To lay out stairs, clamp stair gauges (small brass fittings) or a piece of tape onto the square at the exact riser height on the tongue and the exact going on the blade. For a stair with a 183mm (7.2in) riser and a 260mm (10.25in) going, set one gauge at 183mm on the tongue and the other at 260mm on the blade. This setting stays fixed for the whole board — every mark uses exactly the same two points.
- Lay the stringer board flat, best face up, and decide which edge represents the top of the treads.
- Place the framing square so the riser gauge point and going gauge point both touch the top edge of the board.
- Trace along both arms to mark one riser line and one going line, forming the first step notch.
- Slide the square along the board until the tongue's outer edge lines up with the point where the previous going line met the top edge.
- Repeat the trace for each subsequent step, working the full length of the board.
- Mark the top and bottom cut lines last, once every step notch is drawn, allowing for the birdsmouth at the top and the kicker cut at the bottom.
Know your numbers in 30 seconds
Enter your step count, tread depth and riser height — the stair runner calculator gives you the exact length to order, in metres and feet, with waste included.
Open the stair runner calculatorUsing a story pole to check total rise
A story pole is a straight length of timber marked with the exact riser height stepped off the calculated number of times, held vertically against the actual finished floor levels on site before any stringer is cut. It is the single most effective way to catch an error between the design calculation and reality — if the story pole's top mark does not land exactly at the finished upper floor level, either the total rise was measured wrong at the design stage, or a floor build-up has changed since the drawing was made.
To make one: take a straight batten longer than the total rise, mark the exact riser height calculated for the flight, and step it off with a pair of dividers or by repeated measuring the full riser count. Stand the pole at the base of where the stair will land and check the top mark against the actual finished floor level above. Any discrepancy found here costs nothing to fix; the same discrepancy found after stringers are cut costs a full remake.
| Check | Tool | What it catches |
|---|---|---|
| Total rise on site | Story pole | Floor build-up differences from the drawing |
| Riser/going repeat accuracy | Framing square with gauges | Drift accumulating down the stringer |
| Stringer squareness | Combination square | Notches cut off perpendicular to the board edge |
| Level top and bottom cuts | Spirit level | A stringer that will not sit flat on the floor or ledger |
Laying out the first and second stringer identically
Once the first stringer is marked and cut, use it as a template to mark the second (and third, if fitted) rather than repeating the framing-square process from scratch. Lay the finished stringer over the new board, trace every line exactly, and cut. This guarantees both stringers are truly identical, which a repeated square-and-gauge process cannot guarantee even with a careful carpenter, because the physical act of sliding a square down a board introduces small variations every time it is done freehand.
Cut one stringer, check it against the story pole, then template the rest
Before cutting a second or third stringer, offer the first one up to the actual opening — treads resting loosely in the notches — and confirm the top and bottom land exactly where intended. This single check, taking a few minutes, is what catches an error before it is repeated across every stringer in the build.
Common site errors and how the layout method prevents them
| Error | Cause | Prevention |
|---|---|---|
| Top step taller or shorter than the rest | Total rise measured to the wrong finished level | Check with a story pole before cutting |
| Notches drift out of parallel down the board | Square re-set slightly differently on each mark | Keep gauges locked, slide the square rather than re-setting it |
| Stringers not identical | Each cut marked out separately | Template the second stringer from the first |
| Stair too steep or shallow for the space | Going chosen without checking the 2R+G comfort rule | Validate going against rise before marking any timber |
| Birdsmouth cut too deep, weakening the stringer | Top cut marked without allowing for structural depth below it | Leave a minimum solid depth below any notch, per local code |
UK vs US layout conventions
US carpenters typically work with a stair gauge fitted to an imperial framing square marked in inches and set to a going of 10in and a riser of 7.75in or whatever the design specifies, following the IRC minimums as a floor. UK carpenters use the same square-and-gauge method on a metric-marked square, typically working in millimetres to the tighter tolerance that Approved Document K's exact-riser-height rule implies. The method is identical; only the units and the exact code figures being targeted differ, which is worth knowing if you are working from an American reference video with a UK-built staircase, or vice versa — convert the target numbers first, then follow the same physical steps.
Final checks before cutting
- Confirm total rise on site with a story pole, not just the design drawing.
- Confirm the going satisfies both the comfort rule and any local code minimum (220mm/8.66in UK, 10in/254mm US).
- Lock framing square gauges at the exact riser and going figures before marking the first stringer.
- Mark and cut one stringer fully, offer it up to the actual opening, and only then template the rest.
- Leave adequate solid timber below the deepest notch — check local code for the minimum, commonly around 3.5in (89mm) in the US.
Whatever you decide, get the numbers first: the stair runner calculator doubles as a stair runner length calculator, adding nosing wrap, landings, winders, pattern repeat and waste so you order the right length the first time.
Frequently asked questions
What is a stair layout calculator used for?
It converts the design numbers — riser height, going, riser count — into practical setting-out instructions for marking a stringer with a framing square, and it is the step between a paper design and physically cutting timber. Getting layout wrong is a more common cause of build errors than getting the underlying design maths wrong.
How do I set a framing square for stair layout?
Fit stair gauges to the square at the exact riser height on the tongue and the exact going on the blade, then keep that setting locked for the whole board. Slide the square along the timber for each step rather than re-measuring and re-clamping the gauges each time, which reduces cumulative error.
What is a story pole and why use one on stairs?
A story pole is a batten marked with the calculated riser height stepped off the full riser count, held against the real finished floor levels on site to check that the design's total rise matches reality before any stringer is cut. It is the cheapest and most effective error check in the whole stair-building process.
Should I mark all stringers separately or use a template?
Mark and cut the first stringer carefully with the framing square, check it fits the actual opening, then trace it directly onto the remaining stringer boards as a template. This guarantees identical stringers in a way that repeating the square-and-gauge process freehand cannot.
How much solid timber should be left below a stringer notch?
US IRC R311.7.5.1 effectively requires roughly 3.5in (89mm) of solid material remaining below the deepest point of any stringer notch cut into a 2x12. UK practice follows the same principle of leaving adequate structural depth, sized to the specific timber section being used.
What is the most common stair layout mistake?
Measuring total rise from the drawing rather than checking it on site with a story pole. Finished floor build-ups frequently differ from what a drawing assumes by 10-20mm (0.5-0.75in), which is enough to make the top or bottom step in a finished flight noticeably different from the rest.
Does a stair layout calculator help with carpet or runner planning too?
The riser and going figures a layout calculator confirms are exactly what the stair runner calculator and stair runner length calculator need as inputs, so it is worth carrying the same confirmed numbers straight through from framing to the runner order rather than re-measuring the finished stair from scratch.
Know your numbers in 30 seconds
Enter your step count, tread depth and riser height — the stair runner calculator gives you the exact length to order, in metres and feet, with waste included.
Check my stair layout numbersEvery guide is written from hands-on measuring and fitting experience, checked against the calculator’s own maths, and re-reviewed whenever prices or methods change. Read our editorial standards.