Stair Calculator UK: Rise, Going, Pitch and Stringer (with Diagram)
Calculate your stair rise, going and pitch
Calculate uniform risers, going, total run, pitch, stringer length and an optional headroom estimate. Results include a dimensional check against the selected UK private-stair guidance profile.
Enter your floor-to-floor height and step going. This stair calculator then works out the risers, treads, total run, pitch and stringer length. It also draws your stair to scale and checks it against UK guidance.
More free UK building calculators
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Why one uneven step can fail a whole staircase
Picture this. Your new staircase arrives, and the joiner installs it within a morning. Then you notice the top step feels noticeably taller than the others.
Someone measured the floor before the fitters laid the final flooring. That small difference now sits in one riser, and Building Control can request alterations. Worse, people trip on irregular steps far more frequently than on steep ones.
Stairs depend on rhythm. Every rise and every going must match within a few millimetres of each other. So where should the measurement actually start?
The golden rule: always measure from finished floor to finished floor. Include carpet, tiles or boards that will be there when the stair is in use.
How many stairs for a 2.6 m storey?
A 2.6 m storey usually needs 14 risers of about 186 mm and 13 treads. With a 250 mm going, the flight runs 3.25 m at a pitch of 36.6°.
What are the UK stair rules?
For a private stair in England, the rise must measure between 150 and 220 mm. The going must measure between 220 and 300 mm, with a maximum pitch of 42°.
How to use the stair calculator
The calculator handles a straight flight in metric or imperial units. Builders, joiners and DIYers use it to plan the layout of a wooden stair before cutting any timber. These steps produce the most accurate and reliable design.
- Choose your nation. England, Wales, Scotland and Northern Ireland apply slightly different dimensional limits.
- Pick standard or flush mount. The pictures below show the difference.
- Enter the total rise. Measure from finished lower floor to finished upper floor.
- Enter one going or the total run. Use the going if you know your tread size, or the run if you have restricted floor space.
- Add optional limits. Fix the riser height or the number of risers, then add tread thickness, nosing or headroom.
- Calculate and review the diagram. Download or share the complete report, including the scale drawing.
Standard or flush mount?
How to calculate stairs: rise, going and run
Every straight staircase follows the same five calculations. The calculator above performs them simultaneously, but understanding the method helps you check any quotation.
Stair sizes for common UK floor heights
| Floor to floor | Risers | Rise | Treads | Run at 250 mm going | Pitch |
|---|---|---|---|---|---|
| 2.4 m | 13 | 184.6 mm | 12 | 3.00 m | 36.4° |
| 2.5 m | 13 | 192.3 mm | 12 | 3.00 m | 37.6° |
| 2.6 m | 14 | 185.7 mm | 13 | 3.25 m | 36.6° |
| 2.7 m | 14 | 192.9 mm | 13 | 3.25 m | 37.6° |
| 2.8 m | 15 | 186.7 mm | 14 | 3.50 m | 36.7° |
| 3.0 m | 16 | 187.5 mm | 15 | 3.75 m | 36.9° |
Standard mount, calculated with the tool on this page. All values pass the England private stair checks.
Stair calculator examples for real UK projects
We ran each project through the calculator and compared it with the England guidance profile carefully.
Case study 1: new-build house stair
2.6 m floor to floor with a 250 mm going, standard mount
Case study 2: loft conversion with limited floor space
2.45 m rise, but only 2.6 m of floor for the whole flight
This is precisely why the fixed riser option exists. Restricted loft spaces rarely work on automatic settings. Some loft stairs can also use reduced headroom, so check the guidance for your nation.
Case study 3: garden deck steps
0.9 m deck height with a 300 mm going, flush mount
Building brick or concrete steps instead? Work out the materials with our brick calculator or concrete calculator.
Case study 4: headroom and floor opening
The 2.6 m stair from case study 1, under a 220 mm thick floor
UK stair rise and going limits by nation
Stair guidance differs slightly between the four UK nations. The calculator applies these private stair limits for whichever nation you select.
| Nation | Rise | Going | 2R + G | Max pitch |
|---|---|---|---|---|
| England | 150–220 mm | 220–300 mm | 550–700 mm | 42° |
| Wales | up to 220 mm | 220 mm minimum | 550–700 mm | 42° |
| Scotland | 100–220 mm | 225 mm minimum | 550–700 mm | 42° |
| Northern Ireland | 75–220 mm | 220 mm minimum | 550–700 mm | 42° |
Private stairs in homes. Common, public and external stairs use different limits.
You can read the official documents for England (Approved Document K), Scotland and Northern Ireland. For width, handrails, guarding, landings and older stairs, read our UK staircase regulations guide.
Stair angle calculator: how steep is your staircase?
The pitch is the angle between the staircase and the floor. It derives directly from the rise and going: pitch = arctan(rise ÷ going). A taller rise or shorter going makes the staircase considerably steeper.
| Rise | Going | Pitch | 2R + G | England check |
|---|---|---|---|---|
| 150 mm | 300 mm | 26.6° | 600 mm | Passes |
| 170 mm | 280 mm | 31.3° | 620 mm | Passes |
| 190 mm | 250 mm | 37.2° | 630 mm | Passes |
| 200 mm | 240 mm | 39.8° | 640 mm | Passes |
| 220 mm | 220 mm | 45.0° | 660 mm | Fails the 42° limit |
Our recommendation? Aim for 36–38° in a family home. That range feels comfortable descending with a laundry basket, and it leaves flexibility for later adjustments.
Stair stringer calculator: length and cut rise
Stringers are the sloping side boards that support the treads. The calculator determines their length using Pythagoras, from the stringer height and the total run.
Separate tread boards alter the cutting dimensions. Turn on tread thickness and the calculator reports the stringer cut rise, which is the rise minus the tread. That keeps the first and last steps the same height as the rest.
Most timber flights use two stringers. Wider staircases often need a third in the middle. Your manufacturer or engineer confirms the timber dimensions.
Stair headroom, floor openings and landings
Normal clear headroom is 2,000 mm, measured vertically from the pitch line. The calculator converts that into the minimum floor opening length. Alternatively, enter your opening length to see the headroom you actually achieve.
Does your stair turn at a landing? Calculate each flight separately. Split the total rise at the landing height, and keep every riser the same size across both flights. A landing should be at least as deep as the staircase is wide. Dog leg stairs with a half landing work the same way. Winder and spiral stairs need specialist design, because their goings change across each tread.
Common stair measuring mistakes
- Measuring bare floors. Finishes added later change the top and bottom risers.
- Letting one step absorb the difference. Every riser should match within a few millimetres.
- Confusing going with tread depth. The going is nosing to nosing, while the board itself is deeper.
- Counting treads as risers. A standard stair has one fewer tread than risers.
- Forgetting headroom. A perfect flight still fails if heads collide with the ceiling.
Tiling the treads or the landing afterwards? Our tile calculator works out tiles, boxes and wastage.
Stair calculator FAQs
How the stair calculator checks your design
The calculator converts every measurement to millimetres. It divides the total rise into equal risers, then calculates the treads, run, pitch and stringer length. Finally, it compares the result with the regulations for your selected nation.
The guidance checks never alter the calculated dimensions. Every case study on this page came directly from the calculator. We last verified the official limits in October 2026.
Remember that top step that felt taller than the rest? Measure finished floor to finished floor, check every riser here, and every step stays equal. Reviewed in October 2026. Treat results as a dimensional check, not Building Regulations approval.
Is your stair straight, turning or squeezed into a loft? Tell us through our contact page. Your questions help us decide which staircase tools to develop next.