Stair calculator

Enter the floor-to-floor rise and the going for the risers, treads, run, stringer length, angle and stairwell opening. It checks the stair against Australia's NCC 2025 Housing Provisions, and New Zealand, UK and US rules.

Stair calculator

This calculator needs JavaScript, which is turned off or didn't load. You can still do it by hand: the formulas and worked examples below give the same answers.

Units

Millimetres Feet and inches

What do you know?

Rise only Rise + run Run only

Total rise

Finished floor to finished floor.

Going

One tread, nosing to nosing, measured level.

Advanced: desired riser, floor thickness, headroom, Riser Limited

Desired riser height

Sets the count in Rise + run, and the cap with Riser Limited.

Floor / joist thickness

Upper floor, flooring to ceiling lining.

Headroom height

Clear height above the nosing line.

Riser Limited: round the riser count up, so no riser is taller than the desired riser

Check against

Each country's limits are quoted, with sources, under the calculator.

The same maths as Stairs in the MeisterCalc app: its three modes, its Advanced settings and its Riser Limited option. Millimetres or feet and inches.

Published 6 November 2026 · By Sai Nath

Worked example: a 2700 mm floor-to-floor rise

Total rise 2700 mm, going 240 mm, floor 200 mm thick and 2000 mm of headroom: the values the calculator opens with.

Target riser: (600 − 240) ÷ 2 = 180 mm.
Risers: 2700 ÷ 180 = 15, so 15 risers of 180 mm and 14 treads.
Total run: 15 × 240 = 3600 mm, counted the way the app counts it (risers × going).
Stringer line: √(2700² + 3600²) = 4500 mm, at an angle of 36.87°.
2R + G: 2 × 180 + 240 = 600 mm.
Stairwell opening: (200 + 2000) × 240 ÷ 180 = 2933.3 mm.

Against NCC 2025 every line passes: riser 115–190 mm, going 240–355 mm, 2R + G 550–700 mm and 2 to 18 risers in the flight.

How it works

Rise only: target riser = (600 − going) ÷ 2. Risers = total rise ÷ target riser, rounded to the nearest whole number. Riser height = total rise ÷ risers. Treads = risers − 1.
Rise + run and Run only work from the total run instead. Riser Limited rounds the riser count up, so no riser is taller than the one you set.
Stringer = √(rise² + run²). Angle = arctan(rise ÷ run). Stairwell opening = (floor thickness + headroom) × going ÷ riser.

The check under the result tests the stair against the country you pick, one line per limit with the figure it was tested against.

Stairs in MeisterCalc

Stairs in the MeisterCalc app

Open Home ▸ Stairs, pick Rise Only and enter Total Rise 2700 mm and Going 240 mm. It shows 15 risers of 180.0 mm, 14 treads, a 3600.0 mm run, a 4500.0 mm stringer at 36.87° and a 2933.3 mm stairwell opening, with the flight drawn as you type. It shows an amber warning for a riser over 190 mm (the NCC 2025 Housing Provisions maximum) or under 115 mm, a going under 150 mm or over 450 mm, or a stair steeper than 45°.

On Home, tap Stairs
Pick Rise Only: rise 2700, going 240 mm
Read 15 risers of 180.0 mm

The app version, with every input, result and screen: Stairs in MeisterCalc.

Stairs is one of the three free calculators in the app, with Concrete, Stairs and Check Square: no trial and no account. The others unlock with a one-time purchase, no subscription required, or with a weekly subscription that starts with a 3-day free trial. Every calculation runs on the phone, so it works with no signal on site. It runs on Android 7.0 or later. Get MeisterCalc on Google Play

Questions

What are the NCC stair limits for a house?

For a stair other than a spiral, NCC 2025 Housing Provisions Part 11.2 gives risers of 115 to 190 mm, goings of 240 to 355 mm, 2R + G of 550 to 700 mm and 2 to 18 risers in a flight. Your certifier decides which edition and state variations apply.

How many steps do I need for a 3 m floor height?

With a 250 mm going, the target riser is 175 mm, and 3000 ÷ 175 = 17.1, so 17 risers of 176.5 mm and 16 treads.

Can it do a stair with a landing?

No. It works straight flights. Work out each flight on its own, with the rise of that flight, and set out the landing by hand.

Sources

Building rules are set by the National Construction Code, the NZ Building Code or the Approved Documents and by your council, not by this page or the app.

Stair calculator