Trade & Construction

Stair Calculator

Trade & Construction

Stair Calculator

Live answer16 risersactual riser 175 mm · 15 treads · total run 3,750 mm · comfort check 600 mm

Total rise (millimetres)Vertical height from finished lower floor to finished upper floor or landing.Preferred riser (millimetres)The target riser height before rounding to a whole number of risers.Tread going (millimetres)Horizontal going per tread/nosing line used for the run estimate.Landing allowance (millimetres)Optional extra horizontal allowance for a landing or clear set-out note.

Live result16 risersactual riser 175 mm · 15 treads · total run 3,750 mm · comfort check 600 mm

Formula used

Risers = round(total rise ÷ preferred riser). Actual riser = total rise ÷ risers. Treads in a straight flight = max(0, risers − 1). Total run = treads × tread going + landing allowance. Comfort check = 2 × actual riser + tread going.

This is the method behind the answer, so the result can be checked rather than simply trusted.

Live math canvas

Your numbers, formula and explanation together

Stair Calculator: 16 risers. actual riser 175 mm · 15 treads · total run 3,750 mm · comfort check 600 mm

Formula applied

The exact method behind this answer

CalculationTime keeps the method visible so the number can be checked instead of blindly trusted.

Risers = round(total rise ÷ preferred riser). Actual riser = total rise ÷ risers. Treads in a straight flight = max(0, risers − 1). Total run = treads × tread going + landing allowance. Comfort check = 2 × actual riser + tread going.

Apply the formulaRisers = round(total rise ÷ preferred riser). Actual riser = total rise ÷ risers. Treads in a straight flight = max(0, risers − 1). Total run = treads × tread going + landing allowance. Comfort check = 2 × actual riser + tread going.16 risersactual riser 175 mm · 15 treads · total run 3,750 mm · comfort check 600 mm

Your live breakdown

Current inputs in the calculation

These values come from the controls above and update when the calculator changes.

Total rise: 2,800 millimetres
Preferred riser: 175 millimetres
Tread going: 250 millimetres
Landing allowance: 0 millimetres

Resulting answer

16 risers

actual riser 175 mm · 15 treads · total run 3,750 mm · comfort check 600 mm

Answer: 16 risers
Live support: actual riser 175 mm · 15 treads · total run 3,750 mm · comfort check 600 mm

Assumptions used

What this answer assumes

Use for planning and quote notes only. Confirm code limits before construction.

The calculator treats the stair as a simple straight flight for measurement planning.
The number of risers is rounded to a whole number because partial risers are not usable in a built stair.
A straight flight usually has one fewer tread/going than risers because the upper floor or landing acts as the final step surface.
Australian residential example: many new builds use about a 175 mm riser, 250 mm going and a finished staircase width around 900–1000 mm as a practical planning benchmark.
Inputs are millimetres. The comfort check shown is the common 2R+G rule of thumb, not a building-code approval.
Building codes, maximum riser limits, minimum going, finished width, headroom, handrails, landings, nosings and local permits must be checked separately before construction.

Master’s Tip

How to use the result well

Master’s Tip: measure finished-floor to finished-floor after allowing for floor coverings. A few millimetres of tile, screed or timber can change the exact riser height, and stair risers should be consistent across the flight. Treat 175 mm risers, 250 mm going and 900–1000 mm finished width as an Australian residential planning example, not a compliance certificate.

Printable record

What belongs in the saved calculation

Save the inputs, result, formula, assumptions, page URL and date together so the calculation can be reviewed later.

Total rise: 2,800 millimetres
Preferred riser: 175 millimetres
Tread going: 250 millimetres
Landing allowance: 0 millimetres

What-if check

Nearby riser counts

Changing the whole riser count by one can noticeably change the actual riser height and total run. Use this table before a stair set-out is treated as settled.

Risers	Actual riser	Total run
15	186.7 mm	3500 mm
16 · selected	175.0 mm	3750 mm
17	164.7 mm	4000 mm

Visual proof

Rise ÷ risers, treads × going

The profile is a simplified set-out sketch: total rise is divided into equal risers, while tread going builds the horizontal run.

Visual grid

This result measures part of the space you live in

Length, area, volume and material estimates are grid problems too: measure the space, account for edges and allowances, then turn the pattern into a number you can use.

Micro-timehours, minutes, shiftsHuman scaledays, weeks, projectsMacro-timemonths, years, calendars

Measured output16 risers

Space calculations turn a real surface, room, run or volume into cells, edges and allowances that can be quoted, ordered or checked.

16 risersactual riser 175 mm · 15 treads · total run 3,750 mm · comfort check 600 mm

Inputs

Total rise: 2,800 millimetres
Preferred riser: 175 millimetres
Tread going: 250 millimetres
Landing allowance: 0 millimetres

Method

Total rise 2,800 mm ÷ preferred riser 175 mm = 16 risers. Actual riser = 2,800 ÷ 16 = 175.0 mm. Treads = 16 − 1 = 15. With 250 mm going, total run = 15 × 250 = 3,750 mm. The comfort check is 2 × 175 + 250 = 600 mm. For an Australian residential planning example, a finished stair width of about 900–1000 mm is a common benchmark to check against the drawings.

Assumptions

The calculator treats the stair as a simple straight flight for measurement planning.
The number of risers is rounded to a whole number because partial risers are not usable in a built stair.
A straight flight usually has one fewer tread/going than risers because the upper floor or landing acts as the final step surface.
Australian residential example: many new builds use about a 175 mm riser, 250 mm going and a finished staircase width around 900–1000 mm as a practical planning benchmark.

Notes

Use this space on the printed report for client, supplier, classroom, job-location, measurement, quote or approval notes.