How Much Flooring for a 12x18 Room?
Boxes to order
11 boxes
216 square feet of floor, ten percent waste, boxes of 22.5 square feet.
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How that number is worked out
These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.
- Floor area216 sq ft
- Coverage per box or carton22.5 sq ft
- Waste allowance10 %
Boxes to order11 boxes
| Floor area | 216 sq ft |
|---|---|
| With 10% waste | 237.6 sq ft |
| Boxes at 22.5 sq ft | 11 |
| Coverage bought | 247.5 sq ft |
| Left over | 31.5 sq ftkeep it for repairs |
The material list this produces
| Flooring, boxes | 11 |
|---|---|
| Underlayment, sq ft | 216 |
| Transition strips, each | 2 |
Waste allowance compared
Waste is set by how you lay it, not by how careful you are. Straight lay to herringbone, same room.
| Waste allowance | Boxes to order | With 10% waste | Left over |
|---|---|---|---|
| 5% | 11 boxes | 226.8 sq ft | 31.5 sq ft |
| 10% | 11 boxes | 237.6 sq ft | 31.5 sq ft |
| 15% | 12 boxes | 248.4 sq ft | 54 sq ft |
| 20% | 12 boxes | 259.2 sq ft | 54 sq ft |
What else matters here
Two hundred and sixteen square feet plus ten percent is 237.6, eleven cartons, 247.5 bought.
The material list adds underlayment at the full floor area, and the type matters. Standard foam is a cushion and a small sound barrier. Felt is denser and quieter. Cork is the best of the common options for sound between floors, and it costs accordingly. Over concrete, whatever goes down has to include a vapor barrier or have one taped over it first.
The rule that catches people is that you do not double up. Many planks come with an attached pad already, and adding a second layer under them makes the floor too soft, which stresses the locking joints and is an explicit warranty exclusion in most instructions. Check the back of a plank before buying anything to put under it.
What this calculator assumes
- 10 percent waste covers a straight lay in a simple rectangle. Go to 15 for a diagonal or herringbone lay, and 20 if the room is cut up with closets and angles.
- Buy the whole job in one delivery. Dye lot and batch shade move between production runs, and a single replacement box six months later will not match.
Questions people ask
How many boxes of flooring for a 12x18 room?
About 11 boxes at 22.5 square feet each, covering 216 square feet with ten percent waste.
What kind of underlayment should I use?
Foam for a basic floating floor, felt for more sound deadening, cork for the best sound control between floors. Over concrete it must include or be paired with a vapor barrier.
Can I put underlayment under flooring that has a pad attached?
No. Doubling the cushion makes the floor too soft, stresses the locking joints, and voids most warranties. Check the back of a plank first.
The flooring calculator takes any dimensions you like and hands back the same list.