How Much Flooring Do I Need? Square Feet, Waste, Boxes

Flooring is sold by the box (carpet by the square yard), so the number you need is a box count that covers every room, the cuts, and a spare. Here is the method installers use, the waste allowance for each layout, and a worked example for a whole floor.

1. 1

   Measure each room

   Measure wall to wall at the longest and widest points and round up to the next inch. Split L-shaped rooms into rectangles.
2. 2

   Add closets, halls and doorways

   Anything the new floor runs into gets its own rectangle: closets, hallways, landings and the floor under each doorway.
3. 3

   Add waste for the layout

   About 10% for a straight lay, 15% for diagonal, 15–20% for herringbone or chevron.
4. 4

   Divide by the box coverage and round up

   The square feet per box is printed on the label. Always round up to whole boxes, then consider one spare.

How do I measure a room for flooring?

Measure from wall to wall, not baseboard to baseboard, at the room's longest and widest points. The expansion gap at the edges is small and the waste allowance covers it. Convert inches to feet before multiplying: 3" is 0.25 ft, 6" is 0.5 ft and 9" is 0.75 ft, so a room of 12' × 11' 6" is 12 × 11.5 = 138 sq ft.

For an L-shaped or angled room, split it into rectangles that only touch and add them up (see L-shaped and irregular rooms). Leave out the floor under fixed cabinets and islands unless the new flooring will run under them.

Do closets, hallways and doorways count?

• Closets: yes, if the floor continues into them. Measure each as its own small rectangle.
• Hallways and landings: measure each as a separate rectangle. A 14' hall that's 3' 6" wide is 49 sq ft.
• Doorways: measure into each doorway to where the floor changes, usually under the closed door.
• Transitions: where the new floor meets carpet, tile or a different height, you need a transition piece (T-molding, reducer or threshold). These are bought by the piece, not by area, so list each doorway and its width. Some floating floors also need a break at doorways or along long runs; the manufacturer's installation guide says where.

How much waste should I add?

Waste covers cuts at walls and doorways, offcuts too short to use, and the odd damaged piece. Pergo's planner says to "add a 10% waste factor", and 10% is the usual allowance for a straight lay. Angled and patterned layouts waste more.

These are common installer allowances, not rules. The manufacturer's installation guide wins when it differs.

How many boxes of flooring do I need?

Boxes = floor area × (1 + waste) ÷ coverage per box, rounded up. Coverage varies widely: some Pergo laminate cartons cover 17.18 or 22.09 sq ft, and a COREtec vinyl plank carton covers 28.84 sq ft. Most fall somewhere between about 17 and 30 sq ft, so always use the number on your own label.

Here is a whole main floor, every room getting the same vinyl plank, laid straight:

Add 10% waste: 843 × 1.10 = 927.3 sq ft. Then divide by the box size:

Look at the 22.09 sq ft row: 42 boxes clears the target by half a square foot. That works on paper but leaves nothing for a miscut, so buy a 43rd box. Laid diagonally at 15% waste, the same floor needs 969.5 sq ft, or 49 boxes of 20 sq ft.

Why buy all the flooring from one lot?

Flooring is made in production runs, often called lots, batches or (for tile and carpet) dye or shade lots. Color and shade can shift slightly between runs. Buy the whole job at once, check that the lot numbers on the boxes match, and keep a spare box for repairs. If you come up short later, the store may not have the same lot. Many installers also work from several open boxes at a time so any small variation blends across the floor.

How do I measure stairs for flooring?

Measure stairs separately and don't add them to the floor area. Count the steps, measure one tread's width and depth and one riser's height, and treat any landing as a small room. Each step needs its own cuts and, for hard flooring, a stair nose or tread piece, so stairs are usually priced and installed per step. Give your supplier or installer the count and the measurements and let them quote the stair parts.

What about carpet, tile, laminate and LVP?

• Carpet is priced per square yard (9 sq ft) and cut from rolls of a fixed width, most often 12 ft (13' 6" and 15 ft also exist). The room's width against the roll width decides the seams and the waste, so square footage alone underestimates it. Use the carpet calculator.
• Tile is counted by the piece from the tile size and grout joint. Use the tile calculator.
• Laminate and vinyl plank follow the box math above. The laminate calculator adds underlayment rolls, and the LVP calculator uses your box size.

For any product, the flooring calculator takes rooms or a total, a layout and a box size, and rounds up to whole boxes.

Doing it from the floor plan in FloorFigures

If you have the floor plan, you can skip the tape measure for the first pass. Open the plan in FloorFigures (it's free and runs in your browser). On a PDF it sets the scale from the printed dimensions; press A to find every room. The Takeoff tab lists each room's floor area, flooring with waste and boxes. Set the waste percentage and your box coverage to match the product, then export a CSV for the supplier.