How Many Steps for a 900 mm Rise?

A 900 mm rise needs 5 risers of 180.0 mm and 4 treads. With a 250 mm going the stair is 1.00 m long on plan at a pitch of 35.8°.

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Number of risers (steps up)

5 risers

4 treads, since the top step is the upper floor

Rise of each stepFloor to floor height ÷ the number of risers: 180.0 mm
Going of each tread: 250 mm
Pitch of the stairThe regulations allow up to 42° for a private stair: 35.8 °
2 × rise + goingShould be between 550 and 700 mm: 610 mm
Length of the stair on planThe going of the treads, without any landing: 1.00 m
Meets Part K for a private stair?Rise up to 220 mm, going at least 220 mm, pitch up to 42°: Yes

These are the limits for a private (single-dwelling) stair in Approved Document K for England: a maximum rise of 220 mm, a minimum going of 220 mm, a maximum pitch of 42 degrees, and 2 × rise + going between 550 and 700 mm. The rise and going must be the same for every step in a flight (a tolerance of up to 5 mm is allowed between adjacent steps). You also need a clear headroom of 2.0 m above the pitch line, a handrail, and a guard where there is a drop. Building control approves new stairs, and the rules differ in Scotland, Wales and Northern Ireland.

Before you buy: round up to whole packs, check the size printed on the label, and add a little spare. Your supplier has the final say.

Steps for a 900 mm rise

A height of 0.9 m is typical for a raised deck or a split-level. Measure from the finished floor below to the finished floor above, which is the surface of the top step. The count below uses a 190 mm target rise and a 250 mm going.

Item	Value
Number of risers	5
Rise of each step	180.0 mm
Number of treads	4
Going	250 mm
Pitch	35.8°
2 × rise + going	610 mm
Length on plan	1.00 m

Effect of the rise you choose

A taller rise means fewer steps but a steeper stair. Part K allows up to 220 mm for a private stair.

Target rise	Risers	Actual rise	Pitch	Length on plan
220 mm	5	180.0 mm	35.8°	1.00 m
200 mm	5	180.0 mm	35.8°	1.00 m
190 mm	5	180.0 mm	35.8°	1.00 m
175 mm	6	150.0 mm	31.0°	1.25 m

Effect of the going

Deeper goings are gentler but need more floor space. The minimum going is 220 mm, and 2 × rise + going should be between 550 and 700 mm.

Going	Pitch	2 × rise + going	Length on plan
220 mm	39.3°	580 mm	0.88 m
250 mm	35.8°	610 mm	1.00 m
280 mm	32.7°	640 mm	1.12 m
300 mm	31.0°	660 mm	1.20 m

Use the UK stair calculator to enter your own height and going. Stairs are a safety item: you also need 2.0 m of headroom, a handrail and a guard where there is a drop, so check with building control.

Want to change anything else? The calculator above is the full Stair Calculator (UK): Rise, Going and Building Regulations: edit any number and the results update instantly.

Tools & materials for this project

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Spirit level 600 mm Tape measure 5 m Stair tread gauge (jig)Handrail brackets Non-slip stair treads

Frequently asked questions

How many steps for a 900 mm rise?

5 risers (steps up), each 180.0 mm, with 4 treads because the upper floor is the top step. This uses a 190 mm target rise. A 220 mm rise, the steepest Part K allows, gives 5 risers.

How long is a staircase for 0.9 m floor to floor?

1.00 m on plan with a 250 mm going, before any landing. A shallower going makes the stair shorter but steeper.

Does a 900 mm rise meet Building Regulations?

With 5 risers of 180.0 mm and a 250 mm going, the pitch is 35.8° and 2 × rise + going is 610 mm. Part K for a private stair in England asks for a rise up to 220 mm, a going of at least 220 mm and a pitch up to 42°. Building control approves the final design.

Related sizes and guides

Related sizes

Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.

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