How do I measure stairs for carpet?

Measure one tread depth (the flat part you step on, from nosing to riser), one riser height (the vertical face), and the stair width. Count the total number of treads. The carpet length per step is the tread depth plus the riser height plus the nosing overhang — typically 25mm where the tread wraps over the riser.

What is the standard stair carpet width?

In the UK, stair carpet comes in two standard widths: 686mm (27 inches) for a runner with exposed stair edges, and 914mm for full-width coverage on a standard staircase. If your stairs are wider than 914mm, you may need standard broadloom carpet cut to width.

How many gripper rods do I need for stairs?

You need two gripper rod pieces per tread — one fitted into the angle where the tread meets the riser, and one at the back of the tread against the next riser. Gripper rods for stairs are typically cut to the stair width. Pre-cut stair gripper rods are available from carpet suppliers.

Should I add extra carpet for wastage on stairs?

Yes, add 10% for fitting wastage and trimming. Stair carpet takes more skill to fit than flat floor carpet, and small errors in cutting can waste material. Some fitters also recommend buying an extra 300-450mm so you can shift the carpet up by one step in future to even out wear on the nosings.

What is a nosing overhang?

The nosing overhang is the small lip where the front of the tread extends past the riser below. On most UK stairs this is around 20-30mm. The carpet must wrap around this overhang, so it adds to the total carpet length needed per step. Our calculator defaults to 25mm which suits most standard staircases.

TradeCalculator

Stair Carpet Calculator — Length, Area & Cost

Calculate carpet length, area and gripper rod quantities for staircases. Uses standard UK stair dimensions.

Number of Treads

Count all treads including winders

Tread Depth

UK standard: 220–250mm going

Riser Height

UK standard: 190–220mm rise

Stair Width

Measure between walls or stringers

Carpet Width

Choose runner or full width

Wastage

10% is standard for stairs

Price Per m² (optional)

Enter carpet price for cost estimate

How We Calculate This

This calculator works out the total carpet length needed for your staircase by calculating the carpet required per step and multiplying by the number of treads.

The formula

Carpet per step = Tread depth + Nosing overhang + Riser height

Total length = (Carpet per step × Number of treads) + Landing allowance

What we include

Nosing overhang where carpet wraps around the front edge
Landing allowance at top and bottom (one tread depth each)
Wastage percentage for fitting and trimming
Gripper rod count based on rods per tread

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.