By the carton
Flooring calculator
Measure each room, choose the allowance for how the planks are laid, and enter the square feet printed on the carton to get the number of boxes to buy.
OrderExact · https://orderexact.com/flooring/
Allowance by layout
| Layout | Extra | Notes |
|---|---|---|
| Straight lay, simple room | 10% | The baseline. Covers the cut at the end of every row and the odd damaged plank. |
| Lots of corners, closets or doorways | 15% | Every jog in the wall is another cut, and short offcuts rarely fit anywhere else. |
| Diagonal | 15% | Every plank along a wall is cut at an angle, and an angled offcut is shorter than a square one. |
| Herringbone or chevron | 15–20% | The pattern uses its own left and right planks, and every edge piece is an angled cut. |
| Stairs | Count separately | Treads and nosings are sold by the piece, not by the square foot. |
Boxes, not square feet
Flooring is priced by the square foot and sold by the box. The box count is what you take to the counter, and what you pay for is the boxes times the coverage on the carton, which is always a little more than the room needs. The ticket shows how much more, so you can see what the rounding costs.
Coverage per carton differs between products, even within one brand, so the calculator has no default. Read it off the box or the product listing and type it in.
The same run, all at once
Planks are made in production runs, and color and sheen can shift between them. Every carton carries a run or lot number: check that they match before you leave, and buy the whole job, allowance included, in one trip.
Keep what is left. A plank damaged in five years can be swapped out only if you still have planks from the same run, and a discontinued line cannot be matched at all.
What goes under it and around it
Underlayment only if the planks have no pad bonded to the back, which many vinyl planks and some laminates do. The installation instructions say which, and whether a concrete subfloor needs a vapor barrier as well.
A floating floor needs a gap at every wall so it can move, and baseboard or quarter round covers it. The ticket gives the perimeter to order that trim against: take off the doorways, and the join line if you split one room into pieces. Each doorway where the floor meets a different surface needs a transition strip.
Common questions
How many boxes of flooring do I need?
Measure the square footage, add 10 percent for a straight lay, and divide by the square feet printed on the carton, rounding up. A 12 by 15 foot room is 180 square feet, 198 with the allowance, so at 23.5 square feet a box you need 9 boxes.
How much extra flooring should I buy?
Ten percent for a straight lay in an ordinary room, fifteen for diagonal layouts or rooms with lots of corners, and up to twenty for herringbone. Keep whatever is left for repairs.
How many square feet are in a box of flooring?
It depends entirely on the product, which is why this calculator has no default. The carton and the product listing both print it, usually as square feet per carton. Divide your total by that figure and round up.
Do I need underlayment?
Only if the planks do not have a pad bonded to the back, which many vinyl planks and some laminates do. The installation instructions say which, and whether a concrete subfloor also needs a vapor barrier.
Should I buy all my flooring at once?
Yes. Color and sheen shift between production runs, so check the run number on every carton and buy the whole job, allowance included, in one trip.
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