What it works out
This works out how much flooring a room needs. For laminate or wood boards it's packs; for carpet and sheet vinyl it's metres off the roll. It also works out underlay, and scotia to cover the expansion gap round the edge if you want it.
You can add several rooms and see the total, so it works for a whole floor of a house.
How it works
For boards, the floor area of each room is added up, the waste allowance goes on top, and the total is divided by the area a pack covers. You buy whole packs, so it rounds up.
For carpet and vinyl it's different, because they come in fixed widths. Each room is covered with pieces off the roll, run whichever way uses less, each a little longer than the room for trimming. Offcuts aren't reused between rooms, because joins in the middle of a floor rarely look right.
Underlay covers the floor area in the region's roll sizes. Scotia goes round the edge of each room given by its size, in standard lengths.
A worked example
A room 4 m by 3 m, laid with boards in packs that cover 2.13 m², with underlay.
- Room 1: 4 m × 3 m = 12 m²
- 12 m² + 10% for waste = 13.2 m²
- 13.2 m² ÷ 2.13 m² a pack → 7 packs of 2.13 m² = 14.91 m²
- Underlay: 13.2 m² → 1 roll of 15 m² = 15 m²
The result
- Flooring13.2 m²Buy 7 packs of 2.13 m² (14.91 m²)
- Underlay13.2 m²Buy 1 roll of 15 m² (15 m²)
These are the calculator's own figures for these measurements, with 10% for waste. Change any of them above and it works it out again.
Common mistakes
- Not allowing for waste. Every row ends with a cut, and the offcut only starts the next row if it's long enough. Boards laid diagonally waste more.
- Working out carpet by area. Carpet comes in fixed widths. A room slightly wider than the roll needs a second strip, and the area says nothing about that.
- Forgetting the expansion gap. Floating floors move with temperature and humidity. They need a gap round the edge, covered by skirting or scotia.
- Buying only just enough. Packs from a later delivery can differ in shade. A spare pack also helps if a board is damaged later.
Questions people ask
How many packs of flooring do I need?
Multiply each room's length by its width, add them together, add the waste allowance, and divide by the area on the pack. Round up to whole packs.
How much waste should I allow?
The calculator starts at ten per cent, which suits a straight lay in ordinary rooms. Allow more for diagonal or herringbone patterns, or rooms with lots of corners.
Why is my carpet so much more than the floor area?
Because it's sold off a roll of fixed width. You pay for the full width of every piece, plus a trimming allowance, even where the room is narrower.
Do I need underlay?
Most laminate and engineered boards need one, unless they have one built in. It evens out small bumps and reduces noise, and on a concrete floor you may also need a damp-proof layer. Check the flooring maker's instructions.
What is scotia?
A small quarter-round moulding pinned to the skirting to cover the expansion gap, when you don't want to take the skirting off.