Flooring Calculator

This flooring calculator works out how much laminate, vinyl plank, engineered wood or hardwood flooring you need. Enter the length and width of each room, add as many rooms or areas as you like, and it totals the square footage, adds a waste allowance for cuts and tells you how many boxes to buy.

Waste defaults to 10% for a straight layout and 15% for diagonal or herringbone, and you can type your own figure. Enter the square feet per box printed on the carton for an exact box count, and optionally a price per square foot for a rough material cost. Metric units are available too.

How to Use the Flooring Calculator

1
Measure and enter each room
Type the length and width of the first room. Click Add another room or area for more rooms, closets or the rectangles of an L-shaped space.
2
Choose the layout and waste
Pick Straight (10%), Diagonal (15%) or Herringbone (15%), or type your own waste percentage.
3
Enter the box coverage
Type the square feet per box from the flooring carton or product page. The default is 20 sq ft.
4
Add a price (optional) and read the results
Enter the price per square foot to see a material cost. The results show total area, area with waste, boxes to buy and the square footage those boxes cover.

How the flooring calculator works

Each room's area is its length times its width, and the rooms are added together. That total is increased by the waste percentage to cover cut-offs at walls, doorways and around obstacles. The result is divided by the coverage of one box and rounded up, because flooring is sold only in whole boxes.

If you enter a price, the cost is based on the square footage in the whole boxes you buy, since that is what you pay for. Without a box coverage, the cost uses the area with waste instead.

Area = sum of (length × width) for every room
Area with waste = area × (1 + waste % ÷ 100)
Boxes = ⌈area with waste ÷ sq ft per box⌉
Cost = boxes × sq ft per box × price per sq ft

Worked example: three rooms of laminate

Say you are flooring a 12 x 14 ft living room, a 10 x 11 ft bedroom and an 8 x 5 ft hallway with a straight layout and 10% waste, using laminate that comes in boxes of 22.5 sq ft.

Areas: 12 × 14 = 168, 10 × 11 = 110 and 8 × 5 = 40, for 318 sq ft in total.
With 10% waste: 318 × 1.10 = 349.8 sq ft.
Boxes: 349.8 ÷ 22.5 = 15.5, rounded up to 16 boxes, which cover 360 sq ft.
Cost: if the flooring were $3.00 per sq ft (an example only, prices vary widely), 360 × 3.00 = $1,080 for the flooring alone.

Flooring needed for common room sizes

Box counts assume 20 sq ft per box, rounded up.

Room	Area	With 10% waste	Boxes (10%)	With 15% waste	Boxes (15%)
10 × 10 ft	100 sq ft	110 sq ft	6	115 sq ft	6
10 × 12 ft	120 sq ft	132 sq ft	7	138 sq ft	7
12 × 12 ft	144 sq ft	158.4 sq ft	8	165.6 sq ft	9
12 × 14 ft	168 sq ft	184.8 sq ft	10	193.2 sq ft	10
14 × 16 ft	224 sq ft	246.4 sq ft	13	257.6 sq ft	13
16 × 20 ft	320 sq ft	352 sq ft	18	368 sq ft	19
20 × 20 ft	400 sq ft	440 sq ft	22	460 sq ft	23

Tips and common mistakes

Measure wall to wall at the widest points and include closets and the area under appliances you plan to floor under. Split L-shaped and irregular rooms into rectangles.
Use at least 10% waste for straight layouts and 15% or more for diagonal and herringbone patterns, rooms with many corners, or planks with a strong pattern you want to match.
Check the lot or run number on every box. Buying everything at once from the same lot keeps color consistent, and a spare box is useful for future repairs.
Let the flooring acclimate in the room if the manufacturer calls for it, and leave the expansion gap they specify at walls. Trim covers the gap.
Underlayment, transition strips, baseboard or quarter-round, and adhesive are not included. Underlayment is usually bought by area, so the area with waste is a good guide.

Subfloor and installation notes

The box count assumes a flat, sound subfloor. Most floating floors need the subfloor within a flatness tolerance set by the manufacturer, and some products need a moisture barrier over concrete. Follow the installation guide for your specific product, since warranties often depend on it.

Features

Add several rooms or rectangular areas
Waste presets: 10% straight, 15% diagonal or herringbone (editable)
Boxes needed from the coverage printed on the carton
Optional cost from a price per square foot
US units or metric (m²)

Frequently Asked Questions

How much flooring do I need for a 12x12 room?

A 12 x 12 ft room is 144 sq ft. With 10% waste for a straight layout, you need 158.4 sq ft, which is 8 boxes if each box covers 20 sq ft. For a diagonal or herringbone layout with 15% waste, you need 165.6 sq ft, or 9 boxes. Check your carton, since box coverage varies by product.

How much extra flooring should I buy for waste?

A common guideline is 10% extra for straight layouts and 15% for diagonal or herringbone patterns. Add more for rooms with many corners, angled walls or lots of doorways, and for planks with a strong grain or pattern you want to match. The calculator applies the waste percentage to the total area and then rounds up to whole boxes.

How do I calculate how many boxes of flooring I need?

Multiply the room's length by its width to get square feet, add your waste percentage, and divide by the square feet per box on the carton. Always round up. For example, 168 sq ft plus 10% is 184.8 sq ft, and at 20 sq ft per box that is 9.24, so you buy 10 boxes.

How do I measure an L-shaped room for flooring?

Split the room into two or more rectangles that do not overlap, measure the length and width of each, and add their areas. In the calculator, enter each rectangle as its own room with the Add another room or area link. Include closets and any areas under appliances that will get new flooring.

Should I keep leftover boxes of flooring?

Yes, it is a good idea to keep at least one unopened box if you have one spare. Flooring lines are discontinued and colors vary between production lots, so matching a damaged plank years later can be hard. Store the box flat in a dry place indoors. Some stores accept unopened returns, so check their policy.

Last reviewed September 21, 2026