Flooring Calculator
Rooms with closets, angles, or long runs need more.
Laminate and LVP are sold by carton.
Set to 0 if you are doing it yourself.
Cartons to buy (incl. 10% waste)
17 cartons
- Room area
- 300 ft²
- Area to cover with waste
- 330 ft²
- Leftover after the job
- 10 ft²
- Underlayment rolls
- 4 rolls ($160.00)
Total project estimate
$1,715.00
- Material
- $1,105.00
- Underlayment
- $160.00
- Installation labor
- $450.00
- Blended cost per square foot
- $5.72
Cost figures are placeholders — flooring, underlayment, and especially labor vary widely by region. Cartons are counted to whole units because suppliers don't split them; the leftover keeps future repairs possible. Working with individual tiles instead? Use the tile calculator.
A 15 × 20 ft room (300 ft²) takes 17 cartons of flooring at 20 ft² per carton with a 10% waste allowance, plus 4 rolls of underlayment. At the placeholder prices here — $65 per carton, $40 per roll, $1.50 per ft² for installation — that's $1,105 of material, $160 of underlayment, and $450 of labor: $1,715 total, or $5.72 per square foot. Material and labor are quoted separately so you can price a DIY job against an installed one.
What you're actually paying for
Flooring quotes bundle three different things, and separating them is the whole point of this page:
floor area (ft²) = length (ft) × width (ft)
area + waste (ft²) = floor area × (1 + waste%)
cartons = area with waste ÷ sq ft per carton, rounded up
underlayment rolls = area with waste ÷ sq ft per roll, rounded up
material cost = cartons × price per carton
labor cost = floor area × price per sq ft
total = material + underlayment + labor
Worked example — the page default, a 15 × 20 ft room:
- Floor: 15 × 20 = 300 ft²
- Add 10% waste: 330 ft² → 17 cartons at 20 ft² each (340 ft², so 10 ft² left over)
- Underlayment: 330 ÷ 100 = 4 rolls
- Material 17 × $65 = $1,105; underlayment 4 × $40 = $160; labor 300 × $1.50 = $450
- Total $1,715 → $5.72 per ft²
Note the asymmetry: waste applies to materials, not to labor — you pay a contractor for the floor that exists, not for the offcuts.
Where the money goes
| Line | 15 × 20 ft room (300 ft²) | 12 × 12 ft room (144 ft²) |
|---|---|---|
| Cartons (20 ft² each) | 17 | 8 |
| Material | $1,105 | $520 |
| Underlayment (100 ft² rolls) | 4 rolls — $160 | 2 rolls — $80 |
| Installation labor ($1.50/ft²) | $450 | $216 |
| Total | $1,715 ($5.72/ft²) | $816 ($5.67/ft²) |
The blended cost per square foot barely moves between the two rooms — that's the useful number for comparing quotes, because it folds carton rounding, underlayment, and labor into one figure. Turning labor off drops the default room to $1,265 ($4.22/ft²); skipping underlayment on a floating floor over a concrete slab isn't optional in most installs, but the checkbox lets you see the material-only number.
The three inputs people get wrong
- Waste percentage. 10% suits a rectangular room with a straight lay. Go to 15% for diagonal layouts, many doorways, or rooms with bay windows and closets; 5% is realistic only for a bare square with plank running one direction.
- Carton coverage. Laminate and LVP cartons commonly run 18–25 ft²; check the box. A carton that's 25 ft² instead of 20 ft² drops the default room from 17 cartons to 14.
- Labor basis. Labor is quoted per square foot of floor, not per carton, and installers usually bill the actual measured area plus a minimum. Get a written price per ft² and type it in — national averages are useless for a specific room.
How to use this calculator
- Enter room length and width in feet (measure wall to wall, not around fixed cabinets).
- Set the waste allowance — 10% by default.
- Enter carton coverage and price from the box you're buying.
- Leave underlayment on for floating floors over concrete; enter the roll size and price.
- Add your installer's price per square foot, or set it to 0 for a DIY material-only number.
Frequently asked questions
How much does it cost to floor a 300 sq ft room?
At the placeholder prices here, $1,715 all in — $1,105 of material, $160 of underlayment, and $450 of installation at $1.50/ft², or $5.72 per square foot. Replace the three prices with real quotes; that's the only number that matters.
How many boxes of flooring do I need for 300 square feet?
17 cartons at 20 ft² per carton with a 10% waste allowance (330 ft² ÷ 20 = 16.5, rounded up). Check your carton's actual coverage — 25 ft² cartons bring it to 14.
How much flooring waste should I add?
10% is standard for a rectangular room. Use 15% for diagonal layouts, angled walls, or many transitions; 5% only for a simple square room with a straight plank run.
Do I need underlayment?
For floating laminate and LVP, yes in nearly every install — it's the moisture barrier and the sound layer, and many warranties require it. Glue-down and nail-down products usually don't. The checkbox lets you price both.
Is laminate cheaper than hardwood?
Usually, but this calculator deliberately doesn't answer that: material prices move by product, region, and week. Put both prices in and compare the blended cost per square foot instead of trusting a generic average.
Why is labor calculated on floor area instead of cartons?
Because installers bill the room, not the boxes — you pay for square feet installed and for the extra time on cuts, not for the offcuts in the trash. Waste inflates materials; it doesn't inflate the labor line here.
Data sources: Every figure on this page is arithmetic from the inputs shown — floor area, carton and roll rounding, and the three price lines. $65 per carton, $40 per roll, and $1.50 per ft² of labor are placeholders, not market quotes; get local numbers before you commit, since installation pricing in particular varies widely by region and by job size. Waste guidance (10% standard, 15% for complex layouts) is common estimating practice in the trade, not a manufacturer rule. This is a budgeting tool, not a quote — confirm quantities and underlayment requirements with your installer and the flooring warranty. Related tools: tile calculator, paint calculator, concrete calculator, all home project calculators, compound interest calculator.