Flooring Calculator
Add the length and width of each room, pick a waste allowance and enter the box coverage or plank size. You get the boxes to buy, the total area and an optional cost estimate including underlayment.
How to use the Flooring Calculator
- Choose feet or meters and enter the length and width of each room. Use + Add room for more spaces, and split L-shaped rooms into rectangles.
- Pick a waste allowance: 5% for simple rooms, 10% for most jobs, 15% for diagonal or herringbone layouts.
- Enter the box coverage printed on the box, or switch to plank size and enter the plank length, width and planks per box.
- Add a price per area or per box, and tick underlayment if you need it.
- Press Calculate to see how many boxes to buy and the total cost.
How the flooring calculation works
- Area of each room = length × width. Add the rooms together.
- Area with waste = total area × (1 + waste % ÷ 100).
- Boxes = area with waste ÷ coverage per box, always rounded up to a whole box.
- Cost = boxes × price per box, or boxes × coverage per box × price per sq ft (you pay for every board in a full box).
Example: a 12 × 10 ft living room (120 sq ft) and a 10 × 8 ft bedroom (80 sq ft) make 200 sq ft. With 10% waste you need 220 sq ft. At 20 sq ft per box that is 220 ÷ 20 = 11 boxes, covering 220 sq ft. At $2.50 per sq ft the flooring costs 220 × $2.50 = $550. Underlayment at 100 sq ft per roll needs 2 rolls for the 200 sq ft floor.
Waste allowance guide
| Layout | Typical waste | Why |
|---|---|---|
| Simple rectangular room, straight lay | 5–7% | Few cuts, end offcuts start the next row |
| Most rooms with doorways, closets, hallways | 10% | Extra cuts around door frames and corners |
| Diagonal layout | 15% | Every row ends in an angled cut |
| Herringbone or chevron | 15–20% | Many short pieces and angled border cuts |
Measuring tips
- Measure wall to wall at the widest points and round up to the next inch or centimeter.
- Split L-shaped or irregular rooms into rectangles and enter each one as a separate room.
- Include closets and the space under appliances that will sit on the new floor; leave out permanent cabinets and islands.
- Floating floors need an expansion gap (usually about 1/4 to 3/8 in or 6–10 mm) at the walls. The gap is hidden by baseboards and does not change how much flooring to buy.
- Buy all boxes from the same production lot so the color matches, and let laminate or wood acclimate in the room for the time the manufacturer recommends, often 48 hours.
Box coverage is printed on the carton (for example "20.06 sq ft / 1.86 m² per carton"). If you only know the plank size, multiply length × width × planks per box: 48 in × 7.5 in × 8 = 2,880 sq in = 20 sq ft.
Frequently asked questions
How much flooring do I need?
Measure the length and width of each room, multiply them to get the area and add them together. Then add a waste allowance, usually 10%, and divide by the coverage of one box. Always round up to whole boxes.
How much extra flooring should I buy for waste?
Plan on about 5% for simple rectangular rooms with straight runs, 10% for most rooms with doorways and closets, and 15% or more for diagonal or herringbone patterns, which create more offcuts.
How many boxes of laminate do I need for 200 square feet?
With a 10% waste allowance you need 220 sq ft. If each box covers 20 sq ft, that is exactly 11 boxes. A box that covers 22.5 sq ft would need 9.8, so you would buy 10 boxes.
How do I work out box coverage from plank size?
Multiply the plank length by its width and by the number of planks in the box. For example, 48 in × 7.5 in × 8 planks = 2,880 square inches, which divided by 144 is 20 sq ft per box.
Do I need underlayment?
Most floating laminate floors need a foam or felt underlayment unless the planks have one attached. Many vinyl plank floors have a built-in pad. Check the manufacturer's instructions, since using the wrong underlayment can void the warranty.
Should I keep spare boxes?
Yes. Keeping one spare box makes it easy to replace damaged planks later, and new batches may not match the color exactly. Many stores accept unopened boxes back.