Flooring Calculator guide
Find out how many boxes of vinyl plank, laminate, or hardwood to buy, or how many square yards of carpet a room really takes. Pick the layout to set waste, enter the box coverage, and get a full shopping list with cost.
How to measure a room for flooring
Measure the room's length and width at floor level, wall to wall, and round each up to the next half foot. Multiply for square footage. Then add closets, hallways, and any alcove the new floor will run into; use the extra area box so you do not have to fake a bigger room.
If the room is not a rectangle, split it into rectangles, measure each one, and add them up, or use our square footage calculator and paste the total into the extra area box. Measure in two places along each wall. Older houses are often out of square by an inch or more, and the bigger number is the one that matters.
The formula
Boxes = (room area × (1 + waste %)) ÷ square feet per box, rounded up. Every box of hardwood, laminate, or vinyl plank prints its coverage on the end label, and it varies more than you would think: laminate is often 18 to 24 sq ft per box, LVP 20 to 30, solid hardwood 18 to 25. The calculator fills in a typical number, but type in the one on the product you are buying.
Waste depends on the layout. A straight layout in a plain rectangle wastes about 5%, since offcuts from one row start the next. A typical room with a closet and a couple of doorways is closer to 10%. A 45° diagonal pushes waste to about 15%, and herringbone or chevron to 20%, because every edge piece is an angled cut. The layout menu sets these for you.
Worked example: LVP in a 15 × 12 bedroom
The room is 15 × 12 = 180 sq ft. With a typical 10% waste factor you need 198 sq ft of flooring. If the LVP comes 24 sq ft per box, that is 198 ÷ 24 = 8.25, which rounds up to 9 boxes, or 216 sq ft.
At $3.49 per sq ft, 9 boxes cost about $754. Add underlayment if the planks do not have an attached pad (two 100-sq-ft rolls), and about 54 feet of quarter round to cover the expansion gap at the walls. Over a concrete slab, also lay a 6-mil vapor barrier unless the product says it has one built in.
Carpet is different: it comes in rolls
Carpet is sold in fixed-width rolls, usually 12 feet (some styles come in 15 or 13 ft 2 in). You buy a length off the roll, so room shape matters more than area. The calculator lays strips across the room in both directions, adds 3 inches of trim at each end, and picks the layout with less waste.
For the same 15 × 12 room, one 12-foot strip 15.5 feet long covers it with no seams: 15.5 × 12 ÷ 9 = 20.7, so you buy 21 square yards. Turn the strips the other way and you would need two strips and pay for 33 square yards. A 13-foot-wide room is the painful case: it needs a second strip that is mostly waste. That is why carpet quotes often seem high for the room size.
Common mistakes
Buying exactly the area. Every row ends in a cut, and every doorway and vent needs a notch. Without waste you will run short on the last row.
Mixing lots. Wood and printed laminate vary between production runs. Check that every box has the same lot number, and open and mix planks from three or four boxes as you install so color variation spreads out.
Skipping acclimation. Solid and engineered hardwood usually needs to sit in the room for several days before installation, and the National Wood Flooring Association recommends checking moisture in both the wood and the subfloor. Many LVP products need 48 hours too. Read the installation guide; ignoring it can void the warranty.
Forgetting the expansion gap. Floating floors and wood floors move with humidity. Leave the gap the manufacturer specifies, usually 1/4 to 3/8 inch, and cover it with trim.
When to hire a pro
Click-lock laminate and LVP are two of the most DIY-friendly home projects. Hire a pro for nail-down or glue-down hardwood, herringbone patterns, stairs, subfloors that need leveling or repair, and carpet, which needs a power stretcher and seaming tools to install without ripples. Many stores include measuring in their installation quote, which is a good check against your own numbers.
How we calculate: sources
Frequently asked questions
How much flooring do I need for a 12x15 room?
A 12 × 15 ft room is 180 sq ft. With 10% waste you need 198 sq ft. At 24 sq ft per box that is 8.25, so buy 9 boxes.
How much extra flooring should I buy?
About 5% for straight layouts in simple rectangular rooms, 10% for typical rooms with closets and doorways, 15% for diagonal layouts, and 20% for herringbone or chevron patterns.
How many square feet are in a box of flooring?
It varies by product. Laminate often has 18 to 24 sq ft per box, luxury vinyl plank 20 to 30, and solid hardwood 18 to 25. The coverage is printed on the box end label; enter that exact number.
How do I calculate carpet for a room?
Carpet comes in rolls, usually 12 ft wide, so you buy a length off the roll. A 12 × 15 ft room takes one 12 × 15.5 ft piece (with trim allowance), which is 20.7 sq yd, so 21 sq yd. Rooms wider than the roll need seams and more carpet.
Do I need underlayment for vinyl plank or laminate?
Laminate usually needs foam underlayment unless it has an attached pad. Many LVP planks have a pad attached, and adding another can void the warranty. Over concrete, most products need a 6-mil vapor barrier. Check the installation guide.
Should flooring boxes all have the same lot number?
Yes. Color and finish vary between production runs. Buy everything at once, check lot numbers, and mix planks from several boxes as you install to blend any variation.
Does this flooring calculator save my measurements?
Everything runs in your browser. Nothing you enter is uploaded to a server or stored by us.