Flooring Calculator
Result
Boxes of flooring
- Floor area in square feet
- 180 ft²
- Floor area in square metres
- 16.72 m²
Flooring calculator: measure the room, read the coverage figure off the box you are thinking of buying, and it tells you how many boxes of flooring to bring home. The room area is the easy half — length times width — and the part that catches people is what happens next. A box of laminate covering 24 square feet does not mean a 198 square foot floor takes 8.25 boxes: flooring is sold in whole boxes, so 8.25 rounds up to 9, and the ninth box is not waste, it is the last row and the off-cuts around the door. On top of that the room is never a rectangle and the boards are never laid without a cut, which is what the wastage allowance is for — 10% on a straightforward room, 15% on a room with a diagonal layout, a lot of doorways, a chimney breast or a herringbone pattern. The box coverage is a field rather than a fixed table because it is the one number on this page that the manufacturer has already decided for you: laminate and vinyl plank boxes usually land between 20 and 30 square feet and hardwood between 18 and 24, but a quick-lay plank with an underlayment attached can be half that, and the number is printed on the box you are holding. Leave the default and you get a magnitude; overwrite it with the printed figure and you get your order. Anything that changes the shape of the floor without changing its area — an L-shaped room, an alcove, a cupboard — needs to be split into rectangles and added up, because off-cuts do not transfer between two rooms as readily as the arithmetic suggests.
What one box covers
| Box | Coverage per box (ft²) | Coverage per box (m²) | Boxes per 100 ft² |
|---|---|---|---|
| Laminate | 24 | 2.23 | 4.17 |
| Vinyl plank (LVP) | 30 | 2.787 | 3.33 |
| Hardwood | 20 | 1.858 | 5 |
The fourth column is the fastest way to estimate: multiply your floor area by it and round up. It is the same coverage the page defaults to, so a 360 square foot floor at 4.17 boxes per 100 square feet is about 15 boxes before wastage. These are typical box sizes rather than specifications — they vary by product, plank length and manufacturer, and a box with an attached underlayment or a long-format plank can cover half as much, so check the label before ordering.
Formula
Boxes = ceil( length × width × (1 + wastage ÷ 100) ÷ coverage per box )
- L
- Length of the room, in feet
- W
- Width of the room, in feet
- c
- Coverage of one box, from the label, in square feet
- w
- Wastage allowance as a percentage of the floor area
Use it as soon as you know which product you are buying and have the box in front of you, because the coverage figure is the one input that cannot be looked up reliably. The two decisions that move the answer are the coverage (20 against 30 square feet per box is a 50% difference in how many boxes you carry) and the wastage allowance (10% against 15% is usually one extra box on a normal room). Round up rather than down even when the fraction is small: running short on the last row means a second trip, a dye-lot mismatch on a batch made months later, and a box that may no longer be stocked.
Worked examples
A 12 ft by 15 ft bedroom in laminate, 24 ft² a box
- Floor area: 12 × 15 = 180 square feet (16.72 m²)
- With 10% wastage: 180 × 1.1 = 198 square feet
- Boxes: 198 ÷ 24 = 8.25 → 9 boxes
This is the page's default, and the rounding is the point of the example: the bare arithmetic says 8.25 boxes and you cannot buy a quarter of one. The ninth box is the last row, the cuts around the door and the one spare plank kept against a repair.
A 20 ft by 18 ft living room in vinyl plank, 30 ft² a box
- Floor area: 20 × 18 = 360 square feet (33.45 m²)
- With 10% wastage: 396 square feet
- Boxes: 396 ÷ 30 = 13.2 → 14 boxes
Compare this with the first example and the coverage figure is doing more work than the room size: 360 square feet takes 14 boxes at 30 square feet a box, and the same floor would take 17 at 24. Always type the number from the label rather than trusting the default.
A small 10 ft by 12 ft room at 15% wastage
- Floor area: 10 × 12 = 120 square feet (11.15 m²)
- With 15% wastage: 138 square feet
- Boxes: 138 ÷ 20 = 6.9 → 7 boxes
Small rooms carry a proportionally bigger allowance, not a smaller one: the off-cuts along four walls are a larger share of a small floor, and a 15% allowance on 120 square feet is one extra box. Raising the allowance from 10% to 15% would have made no difference to the answer here — 6.6 against 6.9 both round to 7 — which is worth knowing before arguing with a fitter about it.
Limitations
The area arithmetic is exact; everything after it is an estimate. The coverage per box is the softest number on the page and the default is deliberately a typical figure rather than a specification — boxes run from about 18 to 30 square feet depending on the product, the plank length and whether an underlayment is bonded to the back, so the number printed on the box always beats the number on this page, and the coverage field exists so you can type it in. The wastage allowance is a flat percentage applied to a whole room, which is a crude way to account for the last row, the doorways and the awkward cuts: a plain rectangle with the boards running one way wastes less than a diagonal or herringbone layout, and a room with a chimney breast, an angled bay or a step wastes considerably more. The room is treated as a rectangle — split an L-shaped floor into rectangles and run the page more than once, and remember that off-cuts cannot be reused across two rooms as freely as the arithmetic implies. Not counted here: the underlay, the beading and skirting, the door bars and thresholds, the adhesive if it is a glue-down floor, and the expansion gap at every wall. Finally, boxes are not interchangeable across batches: the same product ordered months apart can arrive a shade different, which is the practical argument for the spare box rather than the mathematical one.
Frequently asked questions
- How many boxes of flooring do I need for a 12 by 15 room?
- Nine, if the box covers 24 square feet and you allow 10%: the floor is 180 square feet, the allowance takes it to 198, and 198 ÷ 24 = 8.25 boxes, which rounds up to 9. Nothing is bought in fractions. Change the coverage to 30 square feet a box and the same room takes 7 boxes, which is why the printed coverage figure matters more than the room measurement.
- Should I round up or down?
- Always up. Flooring is sold in whole boxes and running short on the last row means a second order that may not match the first — the same product made in a different batch can be a shade different, and it may not even be stocked any more. The spare box is not really waste either: keep it unopened against a repair, since a damaged plank from a discontinued batch cannot be replaced.
- How much waste should I add for laminate or vinyl plank?
- About 10% for a plain rectangular room with the planks running one way, and 15% for a diagonal or herringbone layout, a room with several doorways, a chimney breast or an angled bay. Small rooms need proportionally more, because the off-cuts along four walls are a bigger share of a small floor. It is a field rather than a rule of thumb because every room is different.
- Where do I find the coverage per box?
- Printed on the box, usually next to the number of planks or square feet per carton, and often also on the product page. It is the one number this calculator cannot look up for you, because it depends on the product, the plank length and whether an underlayment is bonded to the back — 20 to 30 square feet a box covers most laminate and vinyl plank, and 18 to 24 covers most hardwood.
- Does this work for hardwood flooring too?
- Yes — the arithmetic is the same for solid and engineered hardwood, laminate and vinyl plank. Hardwood usually comes in smaller boxes, though, which is why the default is on the low side of the range, and it usually wants a slightly bigger allowance: boards are cut around every door frame, and a hardwood floor is often laid to a pattern that wastes more at the edges.
- Should I measure each room or the whole floor?
- Measure each room separately and add the boxes up, rather than adding the areas first. Off-cuts cannot be reused freely from one room to the next, and a room-by-room total is less likely to under-count the awkward spaces. For an L-shaped room, split it into rectangles, run each one and add the boxes — the area is the same either way but the box count is usually not.
References
- Approximate Conversions from U.S. Customary Measures to Metric — the chart behind the square feet and square metres on this page — National Institute of Standards and Technology
- The International System of Units (SI) brochure — the square metre the floor area is converted to — Bureau International des Poids et Mesures (BIPM)