How the flooring calculator works
Laminate, engineered wood, luxury vinyl tiles (LVT) and click vinyl planks are all sold in packs that cover a set number of square metres, printed on the box. To work out how many packs you need, the calculator adds up the floor area, adds an allowance for offcuts and mistakes, then divides by the pack size and rounds up to a whole pack:
floor area = length × width (for each rectangle)
flooring needed = floor area × (1 + wastage % ÷ 100)
packs = flooring needed ÷ m² per pack, rounded up
The cost is based on the packs you actually buy, not just the area of the room, because you can't buy part of a pack.
How to measure a room for flooring
- Measure at the widest points, wall to wall, in metres. If the walls aren't straight, use the longer measurement.
- Split awkward rooms into rectangles. An L-shaped kitchen-diner becomes two rectangles that don't overlap. Open "Add more areas" and enter each one.
- Include doorways and the space under radiators, and measure into bay windows and alcoves.
- Don't take off kitchen units unless you're sure the flooring will stop at the plinths. Many fitters run floating floors under appliances like the fridge.
How much wastage should I allow?
Every floor creates offcuts: the last plank of each row is cut to length, and planks around doorframes and pipes are trimmed. The usual rules of thumb are:
| Room or pattern | Wastage to add |
|---|---|
| Simple rectangular room, straight lay | 5 to 10% |
| Rooms with alcoves, bays or lots of doorways | 10 to 12% |
| Diagonal lay | 15% |
| Herringbone or chevron | 15 to 20% |
If you're new to laying flooring, go towards the top of the range. A spare pack is useful for future repairs, and most DIY stores will take back unopened packs with a receipt.
Worked example: a 4.2m × 3.6m living room
- Floor area: 4.2 × 3.6 = 15.12m²
- Add 10% wastage: 15.12 × 1.1 = 16.632m²
- Pack size 2.2m²: 16.632 ÷ 2.2 = 7.56, rounded up to 8 packs
- 8 packs × 2.2m² = 17.6m² of flooring
- At £20 per m²: 17.6 × £20 = £352
Add a 2m × 1.5m alcove and the area rises to 18.12m², which needs 19.93m² with wastage, or 10 packs costing £440.
Don't forget the extras
The price per m² of the flooring isn't the whole cost. Most floating floors also need:
- Underlay, sold in rolls or packs by the m². Buy enough for the floor area without wastage, plus a little for overlaps.
- A damp-proof membrane if you're laying on a concrete floor and your underlay doesn't include one.
- Beading or scotia to cover the expansion gap around the edge if you keep your skirting boards on. Measure the distance around the room and take off doorways.
- Door bars or threshold strips where the new floor meets another floor.
Leave packs of laminate and wood flooring flat in the room for at least 48 hours before fitting, so the boards adjust to the temperature and humidity. Check the manufacturer's instructions, as some products need longer.
Tiling instead? Use our tile calculator, which allows for grout gaps. Decorating the walls too? The paint calculator tells you how many tins of emulsion to buy, and the percentage calculator helps check a sale discount.
Frequently asked questions
How many packs of laminate do I need for a 4m × 4m room?
The room is 16m², or 17.6m² with 10% wastage. With packs of 2.2m² that's 8 packs (17.6 ÷ 2.2 = 8 exactly), so many people buy a ninth pack as a spare.
How much extra flooring should I buy?
Add 10% for a straight lay in a normal room and 15% or more for diagonal, herringbone or chevron patterns. Rooms with lots of corners and doorways need more.
How do I work out the square metres of a room?
Multiply the length by the width in metres. A room 4.2m by 3.6m is 15.12m². For an L-shaped room, split it into two rectangles, work out each one and add them together.
Do I need flooring under kitchen units?
Not usually. Most people stop the floor at the unit plinths, but measure under freestanding appliances such as a fridge or washing machine if you want to be able to move them.
Should I include wastage when buying underlay?
Underlay creates far less waste than boards, so buying for the floor area plus a small margin for overlaps is usually enough.
Last reviewed October 2026 using 2026/27 figures. This calculator gives an estimate for guidance only.