Quick answer: measure each room’s length × width, add them up, then add 10% for a straight layout (15% for diagonal, 15–20% for herringbone). Divide by the coverage printed on one box and round up. Our flooring calculator does it for you.
Buying too little flooring means a second trip, and possibly boxes from a different batch that don’t quite match. Buying far too much wastes money. Here’s how to get it right the first time.
1. Measure each room
- Measure the length and width of the room wall to wall, at the longest and widest points.
- Round up to the nearest inch or centimetre.
- For an L-shaped or irregular room, split it into rectangles and measure each one.
- Include closets, alcoves and the floor under doorways where the new floor runs through.
Don’t bother subtracting small things like a kitchen island or a fireplace hearth. The extra simply becomes part of your waste allowance.
2. Work out the area
Multiply length × width for each rectangle and add them together.
| Area | Size | Square feet |
|---|---|---|
| Living room | 15 × 12 ft | 180 |
| Hallway | 10 × 3.5 ft | 35 |
| Closet | 4 × 2.5 ft | 10 |
| Total | 225 sq ft |
3. Add waste for cuts
Every row ends in a cut, and some offcuts are too short to reuse. Add:
| Layout | Add |
|---|---|
| Straight (parallel to a wall) | 10% |
| Diagonal (45°) | 15% |
| Herringbone or chevron | 15–20% |
| Small rooms, lots of corners or doorways | add about 5% more |
In the example, with a straight layout: 225 × 1.10 = 247.5 sq ft.
4. Convert to boxes
Check the box label for its coverage. It’s usually about 15–25 sq ft for laminate and 20–30 sq ft for vinyl plank, but it varies by brand.
247.5 ÷ 22 sq ft per box = 11.25, so buy 12 boxes. Always round up.
That leaves about 39 sq ft spare. Keep at least one unopened box for future repairs; matching flooring is hard to find a few years later.
5. Don’t forget the extras
- Underlayment: many floating laminate floors need a foam or cork underlay unless the planks have one attached. Rolls commonly cover about 100 sq ft. Some vinyl planks must not have extra underlay, so check the installation guide.
- Moisture barrier: on concrete subfloors, a vapour barrier is usually required.
- Transitions: a strip at each doorway where the flooring meets another floor type, plus end caps at sliding doors.
- Baseboard or quarter-round: measure the room perimeter, subtract doorways, and add about 10% for mitre cuts.
- Spacers, a tapping block and a pull bar: cheap, and they make floating floors much easier to lay.
6. Before you install
- Buy everything at once, from the same production batch (check the lot number on the boxes).
- Acclimatise the planks in the room for as long as the manufacturer says (often about 48 hours for laminate), with boxes laid flat.
- Check the subfloor is flat, clean and dry. Most floating floors allow only small dips over a straight edge.
- Leave an expansion gap around the walls, often about 1/4”–3/8”, as stated in the instructions.
- Mix planks from several boxes as you lay them, so colour variation spreads out naturally.
Worked example: a 12 × 10 ft bedroom
| Step | Result |
|---|---|
| Area | 12 × 10 = 120 sq ft |
| Plus 10% waste | 132 sq ft |
| Box coverage | 20 sq ft |
| Boxes | 132 ÷ 20 = 6.6, so 7 boxes |
| Left over | 140 − 120 = 20 sq ft for cuts and repairs |
Try your own numbers in the flooring calculator. It handles several rooms, layouts and the price per box.
FAQ
How much extra flooring should I buy?
10% for a straight layout, 15% for diagonal and 15–20% for herringbone. Add a little more for small rooms with lots of corners.
Do I need more flooring for vinyl plank than laminate?
Usually no, because the waste allowance is about the same. Vinyl planks are easier to cut cleanly, so offcuts are often more reusable.
Should I include the area under kitchen cabinets?
No. Floating floors normally go up to the cabinets, not under them. Do include open areas under appliances such as the fridge if the floor continues there.
Is it cheaper to buy flooring online?
Sometimes, but factor in shipping weight, return costs and the risk of a different batch if you run short. Many people buy locally so they can see the colour and pick up an extra box quickly.
What else might I need to calculate?
If you’re also repainting the room, our paint calculator works out litres or gallons and the best tin sizes.
How this guide was written: waste allowances and box sizes are typical ranges from flooring manufacturers’ installation guides. Always follow the instructions for the product you buy. See how I test and review.