Carpet Calculator
Enter the room and the width of the roll. The calculator tries both ways of laying the carpet and shows the shorter order, the joins, the offcut and the gripper and underlay.
This is an estimate. Ask your fitter to measure before you order, especially for stairs, bays and doorways.
Worked examples
A bedroom
Room 4.2 m by 3.5 m, 4 m roll, 10 cm trim
4.3 m of carpet, 17.2 square metres, 2.5 square metres offcut
Running the pile along the 3.5 m side would need two pieces and 7.2 m.
About Carpet Calculator
A carpet calculator shows how much carpet to order for a room. Carpet is sold from a roll of a fixed width, usually 4 metres or 5 metres, and you pay for the length you take, so the cheapest way to cut a room is not always obvious. The tool tries running the carpet along the length of the room and along the width, and shows the shorter order.
If the room is wider than the roll, you need more than one piece and a join. The result shows the number of pieces, the area you will pay for and the offcut, so you can compare a 4 metre roll with a 5 metre one. It also gives the length of gripper rod for the edge of the room and the area of underlay.
How to use Carpet Calculator
- Enter the length and width of the room.
- Choose the width of the roll.
- Adjust the trimming allowance and add a price per square metre if you like.
- Read the length to order, the joins, the offcut and the underlay.
Common uses
- Carpeting a bedroom
- Choosing between a 4 m and 5 m roll
- Checking a fitter's quote
- Budgeting for a new living room
Frequently asked questions
How much carpet do I need for a 4.2 m by 3.5 m room?
From a 4 metre roll, run the carpet along the 4.2 metre side. With 10 cm for trimming that is a 4.3 metre length, or 17.2 square metres of carpet for a 14.7 square metre room, leaving an offcut of 2.5 square metres.
Which roll width should I choose?
Pick the width that avoids a join in the room and leaves the smaller offcut. A 5 metre roll suits wider rooms, but it can leave more waste in a small one.
How much underlay do I need?
About the same as the floor area. The tool adds 5% so you have enough for cutting.
Why does the tool allow extra for trimming?
The fitter cuts each piece slightly longer than the room, then trims it to fit. The default is 10 cm, and you can change it.
Does it work for stairs?
No. Stairs are measured and priced separately, as each step and riser needs carpet and the fitter will decide how to cut it.