Guide · Calculator
Stair calculator: flooring, nosing and carpet for stairs
Enter each flight from the plan and choose hard floor or carpet. For hybrid, laminate or vinyl plank you get the product for the treads, risers and landings, the stair allowance, and the nosing lengths to order. For carpet you get the lineal metres off the roll and the square metres you buy. The method is explained step by step below it.
How the calculator works
The calculator measures the product each step needs, not the area the stair covers on the plan. The guide to measuring stairs for hybrid flooring explains why, and how to read the step count, going and riser height off the plan and the section drawings. In short, for each flight:
- Count every riser. Each riser, with the tread above it and its nosing, is one step. Count landings separately, and add winders and box steps as extra steps.
- For hard floor, each step needs its width times the tread depth plus the riser height. A landing needs its width times its length plus one riser.
- Add the stair allowance to that stair product. It goes into the floor total before your normal waste percentage, exactly as in the hybrid flooring calculator.
- Count one nosing for every step edge and every landing edge, and work out how many nosing lengths that takes.
- For carpet, cut a piece for each step, lay the pieces side by side across the roll, and buy whole rows. Landings are cut as their own drops.
The stairs guide uses a round 0.5 m per metre of step width as a quick allowance for the tread, riser and nosing overlap. This calculator uses the measured tread and riser instead, so you can see the real figure. If you prefer the round figure, enter a tread and riser that add up to 0.5 m.
A worked example, done both ways
Example only
The stair, landing and rates are made up to show the arithmetic. They are the figures the calculator starts with.
A straight stair has 14 risers and is 1.0 m wide, with a 250 mm tread and a 180 mm riser. Part way up there is a landing 1.0 m long. That is 13 standard steps and one landing step, which is how the stairs guide counts the same stair.
Hard floor with nosing
| Step | Figure |
|---|---|
| 13 steps, 1.0 × (0.25 + 0.18) | 5.59 m² |
| Landing, 1.0 × (1.0 + 0.18) | 1.18 m² |
| Stair product | 6.77 m² |
| Plus 50% stair allowance, added to the floor before waste | 10.16 m² |
| Nosings: 14 edges at 1.0 m | 14.00 m |
| Nosing lengths of 2.7 m, two edges per length (14 ÷ 2) | 7 lengths |
| Steps at $90 each, 14 × $90 | $1,260.00 |
| Nosing at $60 per length, 7 × $60 | $420.00 |
| Steps and nosing | $1,680.00 |
The 10.16 m² (6.77 × 1.5 = 10.155, rounded) joins the rest of the hard floor, the waste percentage goes on the combined total, and the whole lot is rounded up to packs once. Enter 6.77 m² in the stair field of the hybrid calculator and it does that for you. A 2.4 m nosing would also give 7 lengths here, because only two 1.0 m pieces fit in either.
Carpet off a 3.66 m roll
| Step | Figure |
|---|---|
| Piece per step, 0.25 + 0.18 + 0.05 wrap | 0.48 m long |
| Pieces across the roll, 3.66 ÷ 1.0 rounded down | 3 |
| Rows for 13 steps, 13 ÷ 3 rounded up | 5 rows |
| Steps, 5 × 0.48 | 2.40 lineal m |
| Landing drop, 1.0 + 0.18 + 0.05 | 1.23 lineal m |
| Lineal metres to order | 3.63 m |
| Carpet bought, 3.63 × 3.66 | 13.29 m² |
| Carpet on the stair itself | 7.47 m² |
| Steps at $45 each, 14 × $45 | $630.00 |
The carpet bought is almost twice the carpet on the stair. The fifth row carries one step and two empty spaces, and the landing drop uses 1.0 m of a 3.66 m width. On a 4 m roll, four pieces fit across, so the steps take 4 rows: 1.92 m plus the 1.23 m landing is 3.15 lineal metres and 12.60 m². The guide to carpet lineal metres and roll width explains the same trade-off for rooms.
Why stairs carry an allowance
A stair is cut, not laid. Every tread and riser is a strip cut from a full board, and the offcut from one step rarely suits the next, because the grain, the pattern repeat or the click profile is on the wrong side. Hard floor on stairs is also usually fixed down rather than floating, with more cutting around the nosing. A large allowance on the stair product only, often around 50%, keeps the order honest without inflating the waste on the flat floor. The waste percentage guide shows the full order of operations.
Carpet does not need a percentage in the same way, because the roll layout already shows the waste: the empty spaces in the last row and the strip beside each landing drop. That is why the calculator gives carpet in lineal metres and square metres bought, not with an allowance on top.
Nosing types
Most hybrid, laminate and vinyl ranges offer a matching stair nosing in the floor colour, usually in a few profiles:
- Square edge: a squared profile that caps the front of the tread and overlaps the top of the riser.
- Bullnose: a rounded profile with a small overhang, closer to the look of a traditional timber stair.
- Flush: a profile that finishes level with the surface of the tread, so there is no lip to catch a foot.
Each profile is made for a particular floor thickness, and not every colour comes in every profile. Confirm the nosing exists for the selected product before you quote it, and check the length it is sold in, because that decides how many lengths you order. One nosing per step is cut from a single piece: if the stair is wider than the nosing length, the calculator counts enough lengths to cover each step, but a joined nosing is worth avoiding where a longer length is available. Trims at the top and bottom of the stair, where it meets other floors, are covered in the trims and transitions guide.
Winders and box steps
Winders are the wedge shaped steps on a turning stair. They waste more board than a straight tread, so the stairs guide measures each one at its widest point. In the calculator, either add them as extra steps on the flight, or add a separate flight row for the winders using the widest width. A box step is an open-sided bottom step: count it as an extra step, and allow for the extra nosing that returns down the open side and the extra labour, which the per-step rate does not cover.
Curved and spiral stairs are different again. Every tread is a different shape, the nosing may have to be bent or kerfed, and carpet has to be fitted step by step. Measure them on site and price them as their own item rather than from a calculator.
What the calculator cannot tell you
It does not know whether the treads are concrete, timber or need packing, whether the risers are open, who finishes the stringers, or whether the stair finish in the selections matches the floor above and below it. Those questions decide the price as much as the area does, and the stairs guide lists them. It also assumes all steps in a flight are the same size, treats each flight and each width of nosing separately, and does not plan offcuts from one flight into another. If your installer reuses offcuts, adjust the order by hand.
For carpet, it keeps the pile running down the stair and cuts landings as separate drops. A waterfall or upholstered fit, a pattern repeat or a stair runner changes the piece lengths, so set the wrap allowance to suit your installer.
Feet and square feet
Switch the units to feet and the calculator converts the sizes you have entered and works in feet and square feet. Carpet rolls of 12 ft and about 13 ft 1 in match the 3.66 m and 4 m options. In the US and Canada, stair work is usually priced per step, which the rate fields already allow.
How Squaro does this
Squaro reads each flight from the plan with its finish, step width, step depth and number of steps, and counts open-sided bottom steps. Hard floor stairs get your stair allowance before the normal waste, nosing and steps are priced at your rates, and carpet stairs are priced by your rules. Each flight shows where on the plan it was read, and you check every line before the quote goes to the builder. See flooring quoting software for the rules you can set.
Related reading
- How to measure stairs for hybrid flooringTreads, risers, nosing, landing steps and box steps measured from the plan, with a pricing example.
- Flooring trims and transitions at doorwaysFinding every opening that needs a trim, and pricing trims per item or per metre.
- Hybrid flooring calculator: how many packs do I need?Rooms, allowances and stairs, with waste applied once and rounded up to whole packs.
- Carpet lineal metres and roll width, explainedCutting each room along the roll and pricing the carpet you actually buy.
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