Why is the actual riser height different from my target?

All risers in a staircase must be equal height by code, so the total rise is divided evenly by a whole number of risers — the result is usually close to, but not exactly, your target.

Why is tread count one less than riser count?

The top riser is the floor you're stepping onto, which doesn't need its own tread — a staircase with 15 risers has 14 individual treads plus the top floor.

Is this a substitute for checking local building code?

No — this checks a few dimensional limits from one code, riser height and tread depth among them. Under Approved Document K it also checks the minimum rise, maximum going, pitch and 2R + G; under Australia's NCC, 2R + G and the risers in a flight too; under Canada's National Building Code, the height of the flight. Full stair code compliance also covers headroom, handrail height and graspability, guard requirements, and nosing — always verify the complete set of requirements with your local building department before building.

What do Australia's NCC and Canada's National Building Code set for a house stair?

For a house stair, the NCC sets risers of 115 to 190 mm (4.53 to 7.48 in) and Canada's National Building Code 125 to 200 mm (4.92 to 7.87 in). The NCC Housing Provisions, in Table 11.2.2a, apply that riser range to a stairway other than a spiral stair, with goings of 240 to 355 mm (9.45 to 13.98 in) and twice the rise plus the going between 550 and 700 mm (21.65 to 27.56 in), and no fewer than 2 and no more than 18 risers in a flight. Canada's code gives a private stair, one serving a single dwelling unit, that rise with a run of 255 to 355 mm (10.04 to 13.98 in), and no flight may rise more than 3.7 m (12.14 ft). The codes disagree at the edges: a 197 mm (7.75 in) riser, the most the IRC allows, is over the NCC's 190 mm (7.48 in) and inside the NBC's 200 mm (7.87 in), so check a stair against the code where it is built.

What's the difference between 'recommended tread depth' and 'planned tread depth'?

Recommended tread depth is derived from the 2R+T=25in comfort formula based on your actual riser height — it's a suggestion. Planned tread depth is what you enter as your real design, which is what actually gets checked against the building code's minimum.

Renovation & Construction

Stair Rise & Run Calculator

Divide a total rise into equal risers and set the rise and going beside the US IRC, England's Approved Document K, Australia's NCC or Canada's NBC.

Answers as you typeNo submit button
Every formula citedNamed published standards
Calculated in your browserNo account, nothing uploaded

SettingsSettings for this calculationUS

Market

Imperial · sales tax

Total Rise (floor to floor)

The total vertical height the staircase needs to climb.

Measure straight down from the finished upper floor surface to the finished lower floor surface.

Tools needed: Tape measure, Level

Target Riser Height

A comfortable target, not a code limit: about 175–190 mm (6.9–7.5 in) suits most house stairs.

This is a starting point — the calculator finds the number of risers that divides your total rise as evenly as possible near this target. Each code sets its own limits on the riser it produces, and the one you choose below is checked: the IRC allows up to 7.75 in (197 mm), Approved Document K 150–220 mm (5.91–8.66 in), Australia's NCC 115–190 mm (4.53–7.48 in) and Canada's National Building Code 125–200 mm (4.92–7.87 in) for a private stair.

Planned Tread Depth (Going)

The horizontal depth of each tread (the 'going') you plan to build, front edge to front edge.

This is checked against the going limits of the code you choose (Canada's code calls this figure the run), separately from the comfort-formula recommended depth shown in the results.

Building Code Reference

Which building code to check your stair design against.

Selecting the wrong code for your jurisdiction will give an inaccurate compliance result — check with your local building department if you're unsure which code applies. The choice here sets only the check in the result: the Code thresholds panel further down checks the code of the market chosen in the site's header, whatever is selected here. The Australian option applies Table 11.2.2a of the NCC Housing Provisions for a stairway in a house, other than a spiral stair; a stair serving only non-habitable rooms, such as an attic or a storeroom, that are not used on a regular or daily basis may use the wider limits of Table 11.2.2b instead, which this page does not apply, and a public stairway in other buildings needs a going of at least 250 mm (9.84 in) under NCC Volume One. The Canadian option applies the National Building Code's limits for a private stair, one serving a single dwelling unit; a public stair is tighter, with a rise of no more than 180 mm (7.09 in) and a run of at least 280 mm (11.02 in). Each province and territory adopts the code with its own amendments, and several provinces, among them Ontario, Quebec, Alberta and British Columbia, publish their own, so check the one in force where you build.

Number of risers needed

15 risers

High confidence

WITHIN THE LIMITS CHECKED — US IRC 2024: riser height 7.20 in (183 mm) and tread depth 10.25 in (260 mm) are inside the limits this calculator checks. That is not a compliance determination: headroom, handrails, guards, nosings and width are not checked, and the building control body or inspector decides.

Actual riser height: 7.2 in
Number of treads (steps): 14 treads
Recommended tread depth (comfort formula): 10.6 in
Code max riser height (US IRC 2024): 7.75 in
Code min tread depth (US IRC 2024): 10 in

Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

Comfortable stair proportion rule of thumb: 2 x riser height + tread depth = 24-25 inches; a riser of about 175–190 mm (6.9–7.5 in) is a comfortable target that sits inside all four codes this page checks
US: IRC 2024 R311.7.5 — maximum riser height 7.75 in, minimum tread depth (going) 10 in
UK: Approved Document K (2013), Section 1, Table 1.1 — a private stair's rise 150–220 mm and going 220–300 mm, pitch at most 42°, and twice the rise plus the going between 550 and 700 mm
Australia: ABCB Housing Provisions Standard, Part 11.2, clause 11.2.2 and Table 11.2.2a, called up by NCC Volume Two for houses; the same table in NCC 2022 and NCC 2025. A stairway other than a spiral stair has risers of 115–190 mm, goings of 240–355 mm and a slope relationship 2R + G of 550–700 mm; each flight has not more than 18 and not less than 2 risers (11.2.2(1)(a)); goings and risers are constant through a flight, within 5 mm between neighbours and 10 mm across the flight (11.2.2(1)(c)); and risers have no opening a 125 mm sphere can pass through (11.2.2(1)(d)). Under 11.2.2(2), a stairway serving only non-habitable rooms such as attics and storerooms that are not used on a regular or daily basis may use Table 11.2.2b instead: riser 130–225 mm, going 215–355 mm and 2R + G 540–700 mm. NCC Volume One, clause D3D14 and Table D3D14, gives a public stairway in other buildings a going of 250–355 mm with the same risers and 2R + G
Canada: National Building Code of Canada 2020, Volume 2, Division B, Section 9.8, for a private stair (one serving a single dwelling unit, a house with a secondary suite, or a garage serving either): rise 125–200 mm (Article 9.8.4.1, Table 9.8.4.1), run 255–355 mm (Article 9.8.4.2, Table 9.8.4.2), each tread's depth between its run and its run plus 25 mm (Sentence 9.8.4.2.(2)), risers and runs uniform within 5 mm between neighbours and 10 mm across a flight (Article 9.8.4.4), no flight more than 3.7 m high (Article 9.8.3.3), and 1 950 mm of clear height over a stair serving a single dwelling unit (Sentence 9.8.2.2.(3)). A public stair has a rise of 125–180 mm and a run of at least 280 mm. Provinces and territories adopt the NBC with amendments of their own, so check the edition in force where you build

Inputs used

Total Rise (floor to floor): 9 ft
Target Riser Height: 7.25 in
Planned Tread Depth (Going): 10.25 in
Building Code Reference: US — IRC 2024 (max 7.75 in riser / min 10 in tread)

Intermediate steps

Actual riser height: 7.2 in
Number of treads (steps): 14 treads
Recommended tread depth (comfort formula): 10.6 in
Code max riser height (US IRC 2024): 7.75 in
Code min tread depth (US IRC 2024): 10 in

Final result15 risers

Confidence note: WITHIN THE LIMITS CHECKED — US IRC 2024: riser height 7.20 in (183 mm) and tread depth 10.25 in (260 mm) are inside the limits this calculator checks. That is not a compliance determination: headroom, handrails, guards, nosings and width are not checked, and the building control body or inspector decides.

What this calculation does not cover

Checks riser height and tread depth — and, under Approved Document K, the minimum rise, maximum going, 42° pitch and 2R + G as well. Headroom, handrail height and graspability, guard height, nosing projection and stair width are not checked.
Under Australia's NCC it checks the rise, the going, 2R + G and the 2 to 18 risers a flight may have; under Canada's National Building Code, the rise, the run and the 3.7 m (12.14 ft) a private flight may rise. Neither code's landings, balustrade or guard heights, handrails, headroom or tread construction are checked.
Assumes a single continuous flight — no landing requirements are evaluated.
Winder and spiral stairs follow different rules that this calculator does not model.
Local amendments to the model code frequently differ; confirm with your building department.

Part of bigger jobs

This trade is one line of a job takeoff. Run the whole job and every other trade comes back with it, off the same measurements.

Or plan the space itself: measure it once, doors and windows included, and this figure comes back worked out on that space, with what goes with it.

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Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-10-05 · v1.2.0

Regulatory standards & verification citations5

Comfortable stair proportion rule of thumb: 2 x riser height + tread depth = 24-25 inches; a riser of about 175–190 mm (6.9–7.5 in) is a comfortable target that sits inside all four codes this page checks
US: IRC 2024 R311.7.5 — maximum riser height 7.75 in, minimum tread depth (going) 10 in
UK: Approved Document K (2013), Section 1, Table 1.1 — a private stair's rise 150–220 mm and going 220–300 mm, pitch at most 42°, and twice the rise plus the going between 550 and 700 mm
Australia: ABCB Housing Provisions Standard, Part 11.2, clause 11.2.2 and Table 11.2.2a, called up by NCC Volume Two for houses; the same table in NCC 2022 and NCC 2025. A stairway other than a spiral stair has risers of 115–190 mm, goings of 240–355 mm and a slope relationship 2R + G of 550–700 mm; each flight has not more than 18 and not less than 2 risers (11.2.2(1)(a)); goings and risers are constant through a flight, within 5 mm between neighbours and 10 mm across the flight (11.2.2(1)(c)); and risers have no opening a 125 mm sphere can pass through (11.2.2(1)(d)). Under 11.2.2(2), a stairway serving only non-habitable rooms such as attics and storerooms that are not used on a regular or daily basis may use Table 11.2.2b instead: riser 130–225 mm, going 215–355 mm and 2R + G 540–700 mm. NCC Volume One, clause D3D14 and Table D3D14, gives a public stairway in other buildings a going of 250–355 mm with the same risers and 2R + G
Canada: National Building Code of Canada 2020, Volume 2, Division B, Section 9.8, for a private stair (one serving a single dwelling unit, a house with a secondary suite, or a garage serving either): rise 125–200 mm (Article 9.8.4.1, Table 9.8.4.1), run 255–355 mm (Article 9.8.4.2, Table 9.8.4.2), each tread's depth between its run and its run plus 25 mm (Sentence 9.8.4.2.(2)), risers and runs uniform within 5 mm between neighbours and 10 mm across a flight (Article 9.8.4.4), no flight more than 3.7 m high (Article 9.8.3.3), and 1 950 mm of clear height over a stair serving a single dwelling unit (Sentence 9.8.2.2.(3)). A public stair has a rise of 125–180 mm and a run of at least 280 mm. Provinces and territories adopt the NBC with amendments of their own, so check the edition in force where you build

Which documents these citations point at

International Residential Code — 2024 R311.7.5 (United States)One- and two-family dwellings and townhouses up to three storeys — structure, fire safety, energy, plumbing, mechanical and electrical in a single document.
Approved Documents to the Building Regulations (England) — K (United Kingdom)Practical guidance on meeting the Building Regulations, one lettered part per subject — Part A structure, Part B fire, Part K protection from falling, Part L conservation of fuel and power, and the rest.

A code or standard has force only where a jurisdiction has adopted it, usually with local amendments. This site holds no adoption data for any authority, so check what is in force with the authority where you build. Any section cited above without an edition should be checked against the edition in force where you build. What it would take to know.

Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Tools and safety for this job

To fit the staircase. Generic types, no brands, no prices.

Protection this work requires

Hardwood dust is a recognised carcinogen: extract at the tool and wear a P2/N95 respirator when cutting or sanding indoors.
Boards, blocks and bagged material cause most lasting back injuries on small sites: two people or a lifter for full sheets, and never a bag on one shoulder up a ladder.
Most fatal falls on small jobs are from under three metres: use a tower or a ladder tied at the top, and never work off the top two rungs.

Fit the staircase: Fitting a flight is joinery. Its rise, going (run), pitch, headroom and guarding are set by the building regulations or code the work falls under, and this site flags a geometry that falls outside them rather than approving any stair.

Show the 5 tools this job needs

Essential

Hand saw
Impact driver
Spirit level
Tape measure

Recommended

Combination or framing square

Also needed as materials: impact driver bits.

what each carpentry tool is for, and the spec that decides which to buy where one does.

IRC 2024 also specifies handrail height (34-38 in), minimum headroom (6 ft 8 in), and guard requirements for open sides — none of which this calculator checks, so confirm those separately with your local building department.

Full-size stringer template

Print this stair's stringer at full size — one notch as a step gauge on a couple of sheets, or the whole stringer — with a calibration square and ruler in millimetres and inches on every sheet, so a page your printer shrank is caught before it reaches the saw.

Code thresholds this tool can check

Checked for United States. Each check below names the body that published the limit it uses. Switching market re-runs them. This is not a code review and has no official standing.

These checks cover only the specific numeric limits listed below. They are not a complete code review: fire separation, egress, structural capacity and accessibility provisions are outside their scope, and only the handful of local amendments offered in the selector are modelled — your municipality may have others. Passing every check here does not make a design compliant. Final approval rests with your local building authority.

WITHIN LIMIT — Maximum riser height 7.75 in (197 mm).
Riser height 7.20 in is within the 7.75 in IRC maximum.
ICC · IRC 2024 §R311.7.5.1
WITHIN LIMIT — Minimum tread depth 10 in (254 mm).
Tread depth 10.25 in meets the 10 in IRC minimum.
ICC · IRC 2024 §R311.7.5.2

Now that you have the number

These guides cover the work this quantity is for — the first ones run this calculator inside the section that raises the question.

Building Stairs That Pass Inspectionuses this calculator
A one-millimetre layout error repeats once per riser, so control the whole flight from a single datum and prove the spread before the inspector arrives.
Building Steps Into a Garden Slopeuses this calculator
Dividing an awkward bank into equal risers, matching the going to the ground you actually have, and laying every tread to a fall so it drains instead of icing.
Checking Whether a Loft Can Be Converteduses this calculator
Head height, roof type and joist depth, measured off the timber rather than the plaster, and what each one leaves: a room, a dormer, or nothing.

Called something else where you work? First floor / ground floor · Stair rise and going · Balusters, spindles and stair parts — the term in each market, how close the equivalence really is, and the standard that governs it.

Still deciding? Spiral Stair vs Straight Flight — the factors that actually differ, with no invented prices.

Worked example: Attached deck — step 9 of 11

How to calculate stair rise & run in 5 steps

Total Rise (floor to floor)The total vertical height the staircase needs to climb.
Target Riser HeightA comfortable target, not a code limit: about 175–190 mm (6.9–7.5 in) suits most house stairs.
Planned Tread Depth (Going)The horizontal depth of each tread (the 'going') you plan to build, front edge to front edge.
Building Code ReferenceWhich building code to check your stair design against.
Number of risers neededThe tool computes the number of risers needed from those figures and shows the formula, its sources, and a confidence rating alongside it.

Number of risers needed by total rise (floor to floor)

Page defaults, not your figures above.

Total Rise (floor to floor)	Number of risers needed (risers)
4 ft	7
6 ft	10
8 ft	13
10 ft	16
12 ft	20
14 ft	23
16 ft	26

Frequently asked questions

Why is the actual riser height different from my target?: All risers in a staircase must be equal height by code, so the total rise is divided evenly by a whole number of risers — the result is usually close to, but not exactly, your target.
Why is tread count one less than riser count?: The top riser is the floor you're stepping onto, which doesn't need its own tread — a staircase with 15 risers has 14 individual treads plus the top floor.
Is this a substitute for checking local building code?: No — this checks a few dimensional limits from one code, riser height and tread depth among them. Under Approved Document K it also checks the minimum rise, maximum going, pitch and 2R + G; under Australia's NCC, 2R + G and the risers in a flight too; under Canada's National Building Code, the height of the flight. Full stair code compliance also covers headroom, handrail height and graspability, guard requirements, and nosing — always verify the complete set of requirements with your local building department before building.
What do Australia's NCC and Canada's National Building Code set for a house stair?: For a house stair, the NCC sets risers of 115 to 190 mm (4.53 to 7.48 in) and Canada's National Building Code 125 to 200 mm (4.92 to 7.87 in). The NCC Housing Provisions, in Table 11.2.2a, apply that riser range to a stairway other than a spiral stair, with goings of 240 to 355 mm (9.45 to 13.98 in) and twice the rise plus the going between 550 and 700 mm (21.65 to 27.56 in), and no fewer than 2 and no more than 18 risers in a flight. Canada's code gives a private stair, one serving a single dwelling unit, that rise with a run of 255 to 355 mm (10.04 to 13.98 in), and no flight may rise more than 3.7 m (12.14 ft). The codes disagree at the edges: a 197 mm (7.75 in) riser, the most the IRC allows, is over the NCC's 190 mm (7.48 in) and inside the NBC's 200 mm (7.87 in), so check a stair against the code where it is built.
What's the difference between 'recommended tread depth' and 'planned tread depth'?: Recommended tread depth is derived from the 2R+T=25in comfort formula based on your actual riser height — it's a suggestion. Planned tread depth is what you enter as your real design, which is what actually gets checked against the building code's minimum.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.