Flooring Calculator: Boxes, Square Feet and Waste
Ordering flooring is a balancing act. Order too little and the job stops while you hunt for another box from the same batch. Order far too much and you have paid for flooring you will never lay. This page works out how many boxes of flooring you need for up to three rooms, adds a sensible waste allowance for cuts and mistakes, and shows every formula it uses, so you can check the answer on paper before you spend anything.
Quick answer
For a 10% waste allowance and boxes that each cover 20 sq ft, the most common room sizes work out like this. The amount to buy is the room area plus 10%, and the box count is that figure divided by 20 and rounded up, because you cannot buy part of a box.
| Room size | Room area | Buy (with 10% waste) | Boxes (20 sq ft each) |
|---|---|---|---|
| 10 × 12 ft | 120 sq ft | 132 sq ft | 7 boxes |
| 12 × 12 ft | 144 sq ft | 158 sq ft | 8 boxes |
| 12 × 15 ft | 180 sq ft | 198 sq ft | 10 boxes |
| 15 × 20 ft | 300 sq ft | 330 sq ft | 17 boxes |
Those figures are a starting point, not a promise. A diagonal or herringbone layout, an awkward room shape, or a material that needs more careful matching will push the waste allowance up, which is exactly what the calculator below lets you adjust.
Flooring Calculator
Enter up to three rooms, or type a total area to override the rooms. Pick a material and a laying pattern, then check the box coverage against your own carton label. Results update as you type, or press Calculate. Prices are optional and in your own currency.
Copy this from your carton label — it is the coverage printed on the box you are actually buying.
Enter your room measurements, then press Calculate — the results update as you type.
Box coverage varies by product and brand. The preset is only a default: always replace it with the figure on your carton label before you order.
The formula
The calculator uses four short steps, and each one exists for a practical reason.
- Room area = length × width. Measure each room, multiply its length by its width, and add the rooms together. An L-shaped space is handled the same way, one rectangle at a time.
- Amount to buy = area × (1 + waste %). Waste is not padding for its own sake. It covers the pieces you cut to fit edges, the occasional broken or flawed board, and a small reserve for the future.
- Boxes = amount to buy ÷ box coverage, rounded up. Flooring is sold in whole boxes, so any part of a box becomes another full box.
- Spare = boxes × coverage − amount to buy. This tells you how much coverage the rounding-up leaves you with, which is useful to know before you decide whether to trim an order or keep the extra for repairs.
Nothing here depends on a particular brand. If you know your room area and the coverage printed on a carton, you can follow the same steps with a pencil, and you should get the same answer the calculator gives.
Worked example
Take a straightforward 12 × 12 ft room with LVP flooring laid straight.
- Step 1 — area: 12 × 12 = 144 sq ft.
- Step 2 — add waste: at 10% waste, 144 × 1.10 = 158.4 sq ft to buy.
- Step 3 — boxes: 158.4 ÷ 20 sq ft per box = 7.92, rounded up to 8 boxes.
- Step 4 — spare: 8 boxes × 20 = 160 sq ft, so 160 − 158.4 = 1.6 sq ft of spare coverage.
Now change only the material and the waste. The same 144 sq ft room in solid hardwood at 18% waste needs 144 × 1.18 = 169.92 sq ft — buy about 170 sq ft. Hardwood allows more waste because boards with defects are set aside and cuts for grain direction leave less usable offcut, so the honest allowance is higher even though the room has not changed at all.
Waste percentage by material and pattern
| Material or pattern | Typical waste allowance |
|---|---|
| Laminate, LVP and engineered wood, laid straight | 7–10% |
| Tile | 10–14% (more for diagonal layouts) |
| Solid hardwood | 12–18% |
| Pattern rule of thumb — Straight | 10% |
| Pattern rule of thumb — Diagonal | 15% |
| Pattern rule of thumb — Herringbone | 20% |
Those allowances come from four ordinary causes. Cuts: almost every row ends with a cut piece, and the offcut does not always fit the next row. Breakage: tiles chip and crack, and a plank can split or arrive damaged. Defects: natural wood includes boards you will reject for colour or grain, and manufactured flooring occasionally has a faulty click joint or finish. Future repairs: a small reserve from the original batch lets you replace a damaged section years later without the replacement standing out. Diagonal and herringbone layouts raise all four, because every edge is cut at an angle and far fewer offcuts can be reused.
How to measure an L-shaped room
Do not try to measure an L shape as one room, and do not measure the longest length by the longest width and hope — that counts a corner of floor that does not exist, and you will over-order. Instead, split the room into rectangles. Picture a line across the room where the L changes width, giving you a large rectangle and a smaller one. Measure the length and width of each rectangle, multiply them, and add the two areas together. Enter them as Room 1 and Room 2 in the calculator and it does exactly that sum for you.
Measure closets and alcoves the same way, as their own small rectangles, if flooring will run into them — a walk-in closet usually will, while a shallow cupboard with its own threshold may not. Measure along the longest walls, check whether opposite walls match, and if they differ slightly, use the larger figure. Older rooms are rarely perfectly square, and flooring has to cover the room as it is, not as the floor plan imagined it.
Laminate vs LVP vs hardwood vs tile — buying differences
Laminate is sold in boxes of planks with a printed coverage, and its underlay is usually sold separately, so budget for underlay, beading and door bars on top of the box count. LVP (luxury vinyl plank) also comes in boxes of similar coverage, often with underlay already attached to the plank, which is one reason its cartons can look better value than they first appear — check what is included before comparing prices. Engineered wood is sold in boxes too, with coverage varying more between ranges, while solid hardwood may be sold by the box, the pack or the square metre depending on the supplier, so the coverage figure matters even more. Tile is sold by the case, tiles are counted individually as well as by area, and it needs a cutting allowance because cuts and breakage are unavoidable; grout, adhesive and trim are separate purchases again.
Warning 1 — buy all boxes from the same dye lot or batch. Colour varies slightly between production runs in laminate, vinyl, wood and tile alike. Mixing batches can leave a visible patch in the middle of the floor, so order the full amount, including waste and spares, in one go from one batch, and check the batch numbers on the cartons when they arrive.
Warning 2 — let flooring acclimatise in the room before installing, per the manufacturer instructions. Wood and wood-based flooring in particular expands and settles with the temperature and humidity of the room it will live in. Stack the unopened boxes in that room for the time the manufacturer states — often at least 48 hours — rather than in a cold garage or a damp outbuilding.
Two regional notes. In the UK, flooring is usually sold in packs measured in m², and a laminate pack is roughly 1.5–2.2 m², so use the metric toggle and copy the pack coverage from the label. And hybrid flooring — a rigid waterproof board combining features of laminate and vinyl — is a major category in Australia, which is why it appears as its own preset in the calculator rather than being folded into LVP.
Flooring guides
If you would rather work through the sums yourself before using the calculator, these two guides walk through the measuring, the waste allowance and the box counts step by step.
Frequently asked questions
How much extra flooring should I buy?
For a straight layout in laminate, LVP or engineered wood, add 7 to 10 percent. Use 10 to 14 percent for tile, 12 to 18 percent for solid hardwood, and more for diagonal or herringbone patterns — about 15 and 20 percent. The extra covers cuts, breakage, defects and a small reserve for future repairs.
How many boxes do I need for a 12×12 room?
A 12 by 12 room is 144 sq ft. With LVP at 10 percent waste you need to buy 158.4 sq ft, which is 8 boxes at 20 sq ft coverage per box. The box count changes if your carton covers a different area, so always check the label.
Does a diagonal or herringbone layout need more waste?
Yes. Diagonal layouts cut every edge at an angle and herringbone cuts and turns almost every piece, so far fewer offcuts can be reused. Allow about 15 percent for diagonal and about 20 percent for herringbone, compared with about 10 percent for a straight layout.
How do I measure an irregular or L-shaped room?
Split the room into rectangles, measure the length and width of each one, multiply them and add the areas together. Treat closets and alcoves as separate small rectangles if the flooring runs into them, and use the larger measurement when opposite walls differ.
Should I keep spare planks or tiles?
Yes. Keep a few spare planks or tiles, ideally a full unopened box, from the same dye lot or batch as the floor you laid. Colour varies between batches, so spares from the original order are the only reliable way to make an invisible repair later.
Is carpet calculated the same way?
No. Carpet is sold by the square yard and is made in fixed roll widths, so the number and direction of seams and how the roll width fits your room matter as much as the area. This calculator is for hard flooring sold in boxes, packs or cases.