Carpet calculator
Work out the cut length for one unjoined piece of carpet in a rectangular room, with underlay and fitting checks.
How the number is worked out
- Measure the longest length and widest width. Include any recess that the carpet must cover.
- Add the trimming allowance. The quick estimate adds 10 cm to each measurement. Change it to the figure you are using.
- Check the roll width and direction. One planned room dimension must fit across the exact roll.
- Round the cut length up. The cut-length step you are using is visible and editable.
This first version covers one rectangular room in one unjoined piece. It refuses a room that needs a join instead of estimating one from floor area.
A worked example
A room 4.2 m by 3.6 m, with 10 cm added to each measurement. These are 4 m and 5 m example roll widths, with cuts sold in 0.1 m steps. These are generic example figures, not a product or a fitting plan.
| Working | 4 m roll | 5 m roll |
|---|---|---|
| Floor area | 15.12 m² | 15.12 m² |
| Full piece area | 17.2 m² | 18.5 m² |
| Area outside the measured floor | 2.08 m² | 3.38 m² |
| Cut length | 4.3 m | 3.7 m |
The 5 m roll can be turned for the shorter cut, but direction may matter more than the smaller piece. Check the pile or pattern before ordering.
Mistakes that cost a cut
- Using floor area alone. Carpet comes from a fixed-width roll, so the two room dimensions matter.
- Turning a directional carpet. Pile, stripes or a pattern may have to run one way even when another cut is smaller.
- Guessing a join. Joins, stairs, landings, several rooms and irregular shapes need a cutting plan from a fitter.
- Using the wrong roll width. Use the width offered for the exact carpet, not another carpet in the same range.
- Leaving fitting until last. The subfloor and fitting method decide the underlay, gripper, threshold bars and preparation.
Questions
Can I use it for an L-shaped room?
No. This release accepts one rectangular room only. An irregular room needs a cutting plan that keeps the roll direction and any joins visible.
Does it plan a join?
No. If neither direction fits across the roll, it refuses the estimate and asks for a fitter's cutting plan.
Why can a wider roll need a shorter cut?
The wider roll may fit the longer room dimension across it. The other dimension then becomes the cut length. Only use that direction if the carpet permits it.
Does it count underlay?
Yes, when you enter the area printed on one underlay roll or pack. It rounds up to whole packs.
Does it count gripper and thresholds?
It shows the room perimeter and keeps gripper and thresholds as checks. Their type and quantity depend on the floor, doorways and fitting method.