How to work out how much flooring you need
Flooring is sold by the box, and each box covers a set number of square feet. So the job is to find the floor area, add extra for cuts, and divide by what one box covers. Here is the math the calculator runs, using its starting values: vinyl plank in a 14 x 12 living room and a 12 x 10 bedroom.
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1
Measure each room and add them up
Length times width for each room. 14 x 12 = 168 sq ft and 12 x 10 = 120 sq ft, so 288 sq ft in all. Measure to the wall, not to the baseboard, and include closets you will floor.
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2
Add extra for the pattern
A straight lay needs about 10% more for end cuts and damaged pieces. 288 x 1.10 = 316.8 sq ft.
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3
Divide by the coverage per box and round up
At 20 sq ft per box, 316.8 ÷ 20 = 15.84, so buy 16 boxes. That is 320 sq ft, which costs $960 at $3.00 per sq ft.
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4
Add the trim and transitions
The two rooms have 96 ft of wall. Take off 3 ft for each of the 2 doorways, add 10%, and you need 99 ft of shoe molding, or 13 pieces 8 ft long. Two transition strips and a basic install kit bring the total to about $1,147.
The floor itself is about 84% of that bill. If a pro installs it at $1.50 to $4.00 per square foot of floor, labor adds $432 to $1,152.
How much extra to buy for each pattern
Every row ends in a cut, and the off-cut is not always long enough to start the next row. Angled patterns turn far more of each plank into scrap.
| Layout | Extra to buy | Why |
|---|---|---|
| Straight | 10% | End cuts on each row, a few bad boards |
| Diagonal (45°) | 15% | Angle cuts along every wall |
| Herringbone or chevron | 20% | Two cuts per piece at the edges, layout trial and error |
| Carpet | 10% | Rolls come 12 ft wide, so seams and fill pieces waste some |
Small rooms, hallways and rooms with many corners waste more, because a bigger share of the floor sits along a wall. Many installers also keep one unopened box for future repairs. Most stores take back unopened boxes, so a little extra costs you little.
Boxes needed for common room sizes
Vinyl plank or laminate at 20 sq ft per box. Tap a size to load it into the calculator.
| Room | Area | Straight | Herringbone |
|---|---|---|---|
| 10 x 10 | 100 sq ft | 6 boxes | 6 boxes |
| 10 x 12 | 120 sq ft | 7 boxes | 8 boxes |
| 12 x 12 | 144 sq ft | 8 boxes | 9 boxes |
| 12 x 14 | 168 sq ft | 10 boxes | 11 boxes |
| 14 x 16 | 224 sq ft | 13 boxes | 14 boxes |
| 15 x 20 | 300 sq ft | 17 boxes | 18 boxes |
| 20 x 20 | 400 sq ft | 22 boxes | 24 boxes |
What flooring costs per square foot
Ranges for the flooring itself and for a pro to install it, in 2025–2026 US dollars. Removing the old floor, leveling the subfloor and stairs are extra.
| Type | Material | Labor | Box size |
|---|---|---|---|
| Laminate | $1.50–$3 | $1.50–$4 | 15–25 sq ft |
| Vinyl plank (LVP) | $2–$5 | $1.50–$4 | about 20 sq ft |
| Hardwood | $5–$10 | $4–$8 | 17–25 sq ft |
| Porcelain or ceramic tile | $1–$15 | $5–$10 | 10–16 sq ft |
| Carpet | $1–$4 | $0.50–$2 | by the sq yd |
Laminate and click-lock vinyl are the friendliest DIY floors: no glue, no nails, and a room goes down in a day. Tile and nail-down hardwood take more tools and skill, which is why their labor costs more. Carpet is cheap to install, but stretching it right takes a power stretcher, so most people hire it out.
Grout and thinset for tile floors
For tile, the calculator adds mortar and grout. Mortar coverage depends on the trowel notch, and the notch depends on the tile size. Grout depends on how much joint each square foot holds, so small tiles and wide joints use far more.
| Tile | Trowel | Per 50 lb mortar | Per 25 lb grout, 1/8" |
|---|---|---|---|
| 6 x 6 | 1/4" square | 85–95 sq ft | about 175 sq ft |
| 12 x 12 | 1/4" x 3/8" | 60–67 sq ft | about 348 sq ft |
| 12 x 24 | 1/2" square | 42–47 sq ft | about 461 sq ft |
Large tile needs a large-format tile mortar and, in most cases, back-buttering so the whole tile is bedded. That uses more mortar than the chart, so the calculator takes the low end of each range and adds 10%.
Tips from the trade
- Check the box label, not the shelf tag. Coverage runs from about 15 to 25 sq ft for the same type of floor, and that one number moves your box count more than anything else.
- Buy one lot. Color shifts between production runs. Check that every box shows the same lot or run number.
- Let it acclimate. Wood and many laminates need to sit in the room for a couple of days before you install. Follow the maker's guide; skipping this voids many warranties.
- Leave the expansion gap. Floating floors need a gap at every wall, usually about 1/4 inch, hidden under the baseboard or shoe molding.
- Flat beats level. Most click floors allow only about 3/16 inch of dip over 10 feet. Grind high spots and fill low spots before the first row.
- Mix boxes as you go. Pull planks from three or four boxes at a time so the pattern and shade look natural.
Common questions
How much extra flooring should I buy?
Buy about 10% extra for a straight lay, 15% for a diagonal lay and 20% for herringbone. Add a little more for small rooms, lots of corners or a product you may not be able to match later.
How many boxes of flooring do I need for a 12x12 room?
A 12x12 room is 144 square feet. With 10% extra for a straight lay you need about 158 square feet, which is 8 boxes of vinyl plank or laminate at 20 square feet per box.
Do I need underlayment for vinyl plank flooring?
Not if the planks have a pad attached. Most click-lock vinyl plank sold today does. Adding a second pad can make the joints flex and break, so follow the maker's install guide. Laminate and floating engineered wood usually need a foam underlayment.
How much does it cost to install flooring per square foot?
Labor usually runs about $1.50 to $4 per square foot for laminate and vinyl plank, $4 to $8 for hardwood, $5 to $10 for tile and $0.50 to $2 for carpet. Removing the old floor, stairs and subfloor repair cost extra.
Should flooring run the same direction in every room?
For a floating floor through connected rooms, yes. Planks usually run parallel to the longest wall or toward the main light source, and keeping one direction avoids extra transitions in doorways.
How much grout and thinset do I need for floor tile?
It depends on tile size, joint width and trowel notch. For 12x24 tile with 1/8 inch joints, a 25 lb bag of sanded grout covers about 460 square feet, and a 50 lb bag of large-tile mortar covers about 42 to 47 square feet with a 1/2 inch notch.
Sources and assumptions
Prices are US averages checked in October 2026 and change by region, store and season. Every flooring price and box size in the calculator can be edited.
- Material and labor ranges per square foot: Flooring Clarity, flooring cost guide and HomeAdvisor, flooring installation cost. We use the middle of these ranges as defaults.
- Vinyl plank box size (about 20 sq ft per case) and shelf prices: Home Depot vinyl plank listing (20.06 sq ft per case).
- Thinset coverage by trowel: Custom Building Products, PremiumPlus mortar and VersaBond LHT data sheet.
- Grout coverage: Custom Building Products Polyblend sanded grout coverage chart. The calculator uses joint volume per square foot with tile 3/8 inch thick, calibrated to this chart.
- Waste allowances (10%, 15%, 20%) are common trade practice; check your product's install guide, which may ask for more.
- Supplies at typical big-box prices: foam underlayment $35 per 100 sq ft roll, carpet pad $0.60 per sq ft, shoe molding or baseboard $9 per 8 ft piece, transition strip $25, install kit $20, 50 lb mortar $28, 25 lb grout $25.