Flooring Square Footage Calculator
To calculate the square footage of a room, multiply its length by its width. Use the free calculator below to measure any room, add sections for L-shaped or odd spaces, and include a waste factor so you order the right amount.
Square Footage Calculator
Enter the length and width of each room or area in feet. Add a section for every rectangle in an L-shaped or odd-shaped space, and we'll total them for you.
Flooring pros always order extra for cuts, mistakes, and future repairs. Ten percent covers most rooms.
How to Calculate Square Footage
Square footage is a measure of area. To calculate the square footage of a room, measure the length and width in feet, then multiply them together. The formula is:
Length (ft) × Width (ft) = Square Footage
For example, a room that is 12 feet long and 10 feet wide is 12 × 10 = 120 square feet. That single multiplication answers most measuring questions. The rest of this guide covers the situations that make it slightly less obvious: rooms that aren't perfect rectangles, measurements in inches, and how much extra to buy.
How to Measure a Room, Step by Step
- Measure the length of the room. Using a tape measure, measure the longest wall of the room from one end to the other, in feet. Write the number down.
- Measure the width of the room. Measure the room from side to side, in feet, along a wall perpendicular to the one you just measured. Write this number down too.
- Multiply length by width. Multiply the length by the width. The result is the room's area in square feet. For example, 12 feet by 10 feet equals 120 square feet.
- Break odd shapes into rectangles. If the room is L-shaped or irregular, divide it into separate rectangles. Measure and multiply each rectangle, then add all the square footage totals together.
- Add a waste factor. Add about 10% to your total to cover cuts, mistakes, and future repairs. Multiply your square footage by 1.10 for a standard 10% waste factor.
Calculating Square Footage for L-Shaped and Odd Rooms
Most rooms aren't perfect rectangles. Closets, bay windows, hallways, and open-concept spaces all break the simple length-times-width rule. The fix is the same every time: break the space into rectangles, calculate each one, and add them up.
Take an L-shaped living room. Draw a line to split the L into two rectangles. Say the larger section measures 15 feet by 10 feet, and the smaller leg measures 8 feet by 5 feet:
- Large section: 15 × 10 = 150 sq ft
- Small section: 8 × 5 = 40 sq ft
- Total: 150 + 40 = 190 sq ft
For a room with a bay window or a bump-out, measure that alcove as its own small rectangle and add it. For a diagonal or angled wall, measure the largest rectangle that fits, then treat the triangular leftover as half of a rectangle (length × width ÷ 2) and add it on. The calculator above lets you add a section for each rectangle so the math is done for you.
What If My Measurements Include Inches?
Measure everything in feet for square footage. When a wall lands on a partial foot, convert the inches to a decimal by dividing by 12, since there are 12 inches in a foot. A few common conversions:
- 3 inches = 0.25 ft
- 6 inches = 0.5 ft
- 9 inches = 0.75 ft
So a wall measuring 12 feet 6 inches becomes 12.5 feet. Then multiply as normal: a 12.5 × 10 room is 125 square feet.
Why You Should Add a Waste Factor
Never order the exact square footage of your room. Every flooring installation produces waste: planks get cut to fit at walls and doorways, a few boards arrive damaged or get miscut, and you want leftover material set aside in case a plank is ever damaged and needs replacing years later.
The standard rule is to add 10% to your measured square footage. Multiply your total by 1.10. For a 200-square-foot room, that's 220 square feet to order. Adjust the percentage based on the install:
| Waste Factor | When to Use It |
|---|---|
| 5% | Simple, square rooms with straight walls and few cuts |
| 10% | The safe default for most rooms and most installs |
| 15% | Diagonal layouts, lots of corners, closets, or angled walls |
| 20% | Herringbone and chevron patterns, or very cut-up floor plans |
Turning Square Footage into Boxes of Flooring
Flooring is sold by the box, and each box covers a set number of square feet that varies by product. To find how many boxes you need, take your total square footage (waste factor included) and divide it by the square feet per box, then round up to the next whole box.
Say your total is 220 square feet and the floor you like covers 26.62 square feet per box: 220 ÷ 26.62 = 8.26, so you order 9 boxes. Always round up, because you cannot buy a partial box. The coverage per box is listed on every product page, so once you know your square footage you can find the exact box count for any floor.
The Short Version
Measure length × width in feet for each rectangle, add the sections together, then add 10% for waste. That total is how much flooring to buy. Divide by the square feet per box and round up to get your box count.
The calculator at the top of this page does all of it for you, including L-shaped rooms and the waste factor.
Know Your Square Footage? Start Shopping.
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Frequently Asked Questions
How do I calculate the square footage of a room?
Measure the room's length and width in feet, then multiply them together. Length times width equals square footage. For example, a room that is 12 feet long and 10 feet wide is 12 x 10 = 120 square feet. For rooms that are not a simple rectangle, split the space into rectangles, calculate each one, and add them together.
How do I calculate square footage for an L-shaped room?
Divide the L-shaped room into two or three rectangles. Measure the length and width of each rectangle, multiply to get the square footage of each, then add the results together for the total. For example, a large 15 x 10 section (150 sq ft) plus a smaller 8 x 5 section (40 sq ft) equals 190 square feet total.
How much extra flooring should I buy for waste?
Add a waste factor of about 10% to your measured square footage for most rooms. This covers cuts, mismatched planks, installation mistakes, and leftover material for future repairs. Use 5% for simple, straight rooms and 15% to 20% for diagonal or herringbone installations and rooms with many corners.
How do I convert square footage into how much flooring to buy?
Take your total square footage, including the waste factor, and divide it by the square feet per box listed on the flooring product, then round up to the next full box. For example, 220 square feet divided by 26.62 square feet per box is 8.26, so you would order 9 boxes. The coverage per box is shown on every product page.
Do I measure in feet or inches for square footage?
Measure in feet for square footage. If a measurement includes inches, convert the inches to a fraction of a foot by dividing by 12. For example, 12 feet 6 inches is 12.5 feet. Then multiply length by width as normal.
How do I calculate square footage for stairs?
For each step, measure the depth of the tread (the part you step on) plus the height of the riser (the vertical face), then multiply that combined depth by the width of the stair. Multiply by the number of steps. As a rough rule, budget about 2 square feet of flooring per standard stair step, then add a waste factor.