Design & layout tool
Stair Layout Calculator
Design a full flight from total rise: riser count, going, total run and pitch, with a live section diagram plus headroom, floor-opening and landing checks. Free, no account needed.
Finished floor to finished floor.
7-7.5in is comfortable; risers are equalised.
Horizontal depth, nosing excluded.
Plumb from the nosing line to the ceiling above.
Landings, stringers & handrail
Half-landings or quarter-turns in this flight.
16in suits most treads; 12in for thin or composite.
Measured above the nosing line.
4in (100mm) sphere rule.
Sets the bottom stringer drop.
Your flight
15 risers × 7.33in
14 treads at 10.50in / 26.7cm · 36.8 degree pitch
- Riser height (equal)
- 7.33in / 18.6cm
- Tread run (going)
- 10.50in / 26.7cm
- Total run
- 147.00in / 373.4cm
- Cut line (diagonal)
- 183.60in / 466.3cm
- Stringer stock length
- 195.60in / 496.8cm (16.3ft)
- Pitch
- 36.8 degrees
- 2R + G
- 25.17in / 63.9cm
- Stringers
- 4 at 12.0in centres (65.2ft stock)
- Handrail length
- 207.60in / 527.3cm (17.3ft)
- Balusters
- 39 at 5.2in centres
Code & comfort checks
IRC (US) allows a maximum 7.75in riser. Every riser in a flight must match within 3/8in.
Minimum going is 10.00in. Shallow treads are the single biggest cause of descending falls.
Comfortable domestic flights sit between 30 and 37 degrees; 42 degrees is the absolute ceiling.
Two risers plus one going should land between 24in and 25in (600-640mm) for a natural stride.
IRC (US) expects at least 36.0in of clear width above the handrail height.
Minimum headroom is 80in measured plumb from the tread nosing line.
IRC wants a graspable handrail 34-38in above the nosing line, continuous for the full flight, and no gap that passes a 4in sphere.
Guidance only — confirm against your local building control before you cut or pour.
Compare riser counts
| Risers | Riser | Going | Run | Pitch |
|---|---|---|---|---|
| 14 | 7.86in | 10.50in | 11.4ft | 38.9° |
| 15 | 7.33in | 10.50in | 12.3ft | 36.8° |
| 16 | 6.88in | 10.50in | 13.1ft | 34.9° |
The highlighted row is your current flight. Nudging the riser count is usually the cheapest way to bring a steep or shallow stair back inside code.
Advanced layout
Mark-out schedule, framing deductions & take-off
Quick answer
How do you calculate a stair layout?
A stair layout is set by four numbers: total rise, riser count, going (tread run) and total run. Divide total rise by your target riser height and round to a whole number of risers, divide the rise back by that count for the exact riser, then multiply going by (risers - 1) for total run. Check headroom, floor-opening length and landing depth against that footprint before you cut anything — a layout that fits on paper often fails on headroom.
- Risers = round(total rise / target riser); exact riser = total rise / risers.
- Total run = going x (risers - 1) on a flight that lands flush with the upper floor.
- A landing adds its own depth — normally at least the stair width — to the footprint.
- Headroom of 6ft 8in (2m) is measured vertically from the pitch line.
- The floor opening, not the flight, is usually what limits a layout.
- Draw the section before ordering: layout errors are the expensive kind.
A layout is four numbers and three checks
Every stair layout resolves to total rise, riser count, going and total run. Get those four right and the flight is buildable; get them wrong and no amount of careful carpentry rescues it. The three checks that sit on top are headroom, floor-opening length and landing depth, and they are what turn an arithmetically correct layout into one that actually fits the building. Work in that order every time — numbers, then checks, then materials.
| Floor-to-floor rise | Risers at ~7in | Exact riser | Run at 10in going |
|---|---|---|---|
| 96in (8ft) | 14 | 6.86in | 130in |
| 104in | 15 | 6.93in | 140in |
| 108in (9ft) | 15 | 7.20in | 140in |
| 2600mm | 14 | 185.7mm | 3250mm |
| 2800mm | 16 | 175.0mm | 3750mm |
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 calculatorWorked example: fitting a flight into a fixed opening
Total rise is 104in and the available run is 132in. At a 7in target riser you get 15 risers and an exact riser of 6.93in, but 14 goings at 10in needs 140in — 8in more than you have. Two ways out: reduce the going to 9 3/8in (14 x 9.375 = 131.25in), which pushes 2R+G to 23.2in and is still comfortable; or keep the 10in going and turn the last two steps as winders, which buys back the footprint at the cost of a trickier balustrade and a harder runner fit.
Headroom is what usually kills a layout
Headroom is measured vertically from the pitch line to the underside of whatever is above — trimmer, ceiling, sloping roof — and 6ft 8in (2m) is the usual minimum. Because the pitch line climbs, the critical point is rarely where people expect it: on a loft stair it is often two or three steps from the top, and on a stair under a landing it is at the trimmer. Check the specific worst point rather than an average, and lengthen the floor opening rather than steepening the flight where you have the choice.
Draw the section before you buy
Print the section diagram, mark the trimmer and the worst headroom point on it, and check it against a tape on site. Ten minutes here saves the two most expensive stair mistakes: an opening cut too short and a flight ordered to the wrong rise.
Layouts with landings, turns and winders
An L-shaped or U-shaped layout is just two flights and a landing, so set each flight out independently and treat the landing as one riser of climb plus its own depth. Keep the landing at least as deep as the stair is wide, and remember that a quarter-turn made of winders is not the same as a landing — winders keep climbing through the turn, which is why they save space and why they are harder to finish. If a runner is going down the finished stair, the winder geometry drives the cutting list, and the stair runner calculator doubles as a stair runner length calculator that handles the extra wrap those tapered treads need.
From layout to material take-off
Once the layout holds, the take-off follows from it: stringer length is the diagonal of rise and run, tread and riser boards come from the counts, and the balustrade divides along the pitch line. Add nosing projection to tread depth for any covering, and carry the exact riser height through to the balustrade schedule rather than rounding it — a 0.07in rounding error over 15 risers is a visible 1in discrepancy at the top.
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
How do I lay out a staircase from scratch?
Measure total rise from finished floor to finished floor, choose a target riser around 7in (175mm), divide and round to whole risers, then divide the rise back by that count to get the exact riser height. Pick a going that satisfies your code and the 2R+G comfort rule, multiply it out for total run, and check the result against the available floor space, floor opening and headroom before committing.
Can this calculator handle a stair with a landing?
Yes. Set out each flight separately — risers and going for the lower flight, then the upper — and add the landing depth between them. The landing counts as one riser's worth of climb and should normally be at least as deep as the stair is wide, so a 36in wide stair wants a 36in landing minimum.
Does it produce a diagram?
Yes — the tool draws a live section as you type, showing rise, run, pitch line and the notch pattern, so you can see immediately whether a layout is shallow, steep or out of proportion before you look at the numbers.
How long does the floor opening need to be?
Long enough that the pitch line clears the trimmer by the required headroom. In practice you work backwards: mark the point where headroom becomes critical, measure the vertical distance to the pitch line, and lengthen the opening until it clears. This is the single most common reason a stair layout has to be redesigned.
What is the 2R + G rule?
Twice the riser plus the going should fall roughly between 22in and 25in (550-700mm metric equivalents vary by standard). It is a comfort check rather than a legal one, and it is a fast way to spot a layout where a legal riser has been paired with an uncomfortably shallow tread.
How much floor space does a straight flight need?
Roughly 12-14ft of run for a standard 8ft floor-to-floor height with comfortable proportions. If you only have 9 or 10ft, the realistic options are a quarter-turn with winders, an L-shaped flight with a landing, or a steeper pitch — all of which trade footprint for comfort.
Can I use the layout for both timber and concrete stairs?
The rise-and-run arithmetic is identical. What changes is the build-up: timber layouts hang off a stringer notch, while concrete layouts need formwork cut to the same diagonal plus an allowance for the finish thickness on treads and risers. The concrete stair calculator covers that allowance.
Is the stair layout calculator free?
Yes. Rise, run, riser count, going, pitch, the section diagram and code checks are all free with no account. A free account adds the printable mark-out schedule and saves the layout against a project.
Related tools & guides
Start with the numbers: our stair runner calculator also works as a stair runner length calculator, adding nosing wrap, landings, winders, pattern repeat and waste so you order the right length first time.