You found the perfect tile, so how many boxes should you buy to avoid running short? To calculate flooring and tile quantities, measure the floor area, divide by the size of one tile or plank, round up to full boxes, then add a waste factor for cuts. This guide walks each step with a clear worked example so you order the right amount the first time.
Measure the floor area in square feet (length x width). Divide that area by the size of one tile or plank to get the tile count. Round up to full boxes using the coverage printed on the box. Add 10 percent for waste, or 15 to 20 percent for diagonal or patterned layouts. Example: a 120 sq ft room with 1 sq ft tiles needs about 132 tiles, which is 14 boxes after 10 percent waste.
Step 1: Measure the Floor Area
Start with the size of the space you want to cover. Measure the length and width of the room in feet. Multiply the two numbers to get the floor area in square feet.
The formula is simple: area = length x width. A room that is 12 ft long and 10 ft wide gives 12 x 10 = 120 sq ft. Write that number down, because every later step builds on it.
Have more than one room? Measure each one on its own, then add the areas together. Two rooms of 120 sq ft and 80 sq ft total 200 sq ft of flooring. If a room is not a plain rectangle, see the tips for tricky rooms further down.
A steel tape measure and a quick sketch of the room make this easier. Note each wall length on the sketch as you measure. Round each measurement up to the nearest inch so you never come up short.
Step 2: Divide by Tile or Plank Size
Now turn square feet into a piece count. Divide the floor area by the size of one tile or plank in square feet. The result is how many pieces cover the bare floor.
Most tiles are sold by their inch size, so convert first. A 12 in x 12 in tile is 144 square inches, and 144 / 144 = 1 sq ft. So each tile covers 1 sq ft, and 120 sq ft / 1 = 120 tiles.
Plank flooring works the same way. Find the coverage of one plank in square feet, then divide. The table below lists common sizes to save you the math.
| Piece Size | Coverage per Piece | Pieces per 120 sq ft |
|---|---|---|
| 12 in x 12 in tile | 1.00 sq ft | 120 |
| 12 in x 24 in tile | 2.00 sq ft | 60 |
| 6 in x 36 in plank | 1.50 sq ft | 80 |
| 7 in x 48 in plank | 2.33 sq ft | 52 (rounded up) |
These counts are for the bare floor only. You still need to round up to boxes and add waste, which the next two steps cover.
Buy by the Box
Stores sell tile and flooring by the box, not by the single piece. Each box lists how many square feet it covers. Divide your floor area by that coverage, then round up to the next whole box.
Say a box covers 10 sq ft. For a 120 sq ft floor, 120 / 10 = 12 boxes to reach the bare area. You cannot buy part of a box, so always round any fraction up to the next full box.
Measure every room twice before you order. A small error on one wall multiplies across the whole floor. For long, narrow spaces like hallways, add an extra box, since long runs leave more cut-off waste.
Rounding up is not optional. A count like 12.3 boxes means you must buy 13, because 12 boxes would leave a gap. Do this rounding after you add the waste factor in the next step, so your extra pieces are included in the box total.
Add a Waste Factor
You never install every piece whole. Cuts at walls, doorways, and corners create scrap, and a few tiles may crack or arrive chipped. A waste factor covers those losses so you do not run short mid-job.
Multiply your tile count or area by the waste percentage, then round up to full boxes. Use these typical guidelines:
- Straight or grid layout: add 10 percent (the standard).
- Diagonal layout: add 15 percent, because angled cuts waste more.
- Herringbone or patterned layout: add 15 to 20 percent.
- Busy rooms with many corners, closets, or angles: lean toward the higher end.
Worked example: 120 tiles x 1.10 = 132 tiles for a straight layout. At 10 sq ft per box, 132 / 10 = 13.2, so buy 14 boxes. A diagonal layout uses 120 x 1.15 = 138 tiles instead. Always buy from the same batch or lot number, since color and shade can shift between production runs.
Keep any leftover full tiles once the job is done. They are your best match for a future repair, since a replacement bought later may come from a different lot. Store the spares flat in a dry place.
Tips for Tricky Rooms
Few rooms are a perfect rectangle. The fix is to break an odd shape into smaller rectangles, find each area, then add them up.
- L-shaped rooms: split the floor into two rectangles, measure each, and add the areas together.
- Closets and alcoves: measure them as small rectangles and include them in the total.
- Doorways and thresholds: add a little extra length where flooring runs into the next room.
- Large fixtures: you can subtract a big built-in island, but many pros leave it in for a safety margin.
When in doubt, round up rather than down. A leftover box is cheaper than a second store trip and a possible batch mismatch. This method covers flooring and tile only; for wall coverage see our guides on how much paint you need and how to estimate drywall for a room.
Skip the pencil-and-paper math. Enter your room size, tile size, and waste factor into our Tile and Flooring Calculator and get the exact tiles and boxes to buy in seconds. It rounds up to full boxes for you, so you never run short. Try a few tile sizes and layouts to compare the box counts before you head to the store.
Frequently Asked Questions About Flooring and Tile Quantities
How Do I Calculate How Many Tiles I Need?
Measure the floor area in square feet by multiplying length times width. Divide that area by the size of one tile in square feet to get the piece count. Then add a waste factor, usually 10 percent, and round up to full boxes. A 120 sq ft room with 1 sq ft tiles needs about 132 tiles.
How Much Waste Should I Add for Flooring?
Add about 10 percent for a straight or grid layout. Use 15 percent for a diagonal layout, and 15 to 20 percent for herringbone or other patterns. Rooms with many corners, closets, or angles need the higher end. The extra covers cut scrap, breakage, and future repairs.
How Many Boxes of Flooring Do I Need?
Divide your total square footage, including waste, by the coverage printed on the box. Then round up to the next whole box. If you need 132 sq ft and a box covers 10 sq ft, that is 13.2 boxes, so you buy 14. You cannot buy part of a box.
Do I Subtract for Cabinets or Islands?
You can subtract the footprint of a large built-in island or a bank of cabinets that flooring will not run under. Many installers leave small fixtures in the total for a safety margin. Never subtract for furniture, since it moves and the floor still runs beneath it.
Why Buy Tiles From the Same Batch or Lot?
Color and shade can shift slightly between production runs. Tiles from one batch or lot number match best, so buy your full amount at once, including waste. Keeping a few spare tiles from that same lot also helps if you ever need to replace a cracked piece later.
How Do I Handle an L-Shaped Room?
Split the L shape into two rectangles. Measure the length and width of each rectangle, multiply to get each area, then add the two areas together. Use that combined square footage for the rest of the math. This same split-and-add trick works for any irregular room.
How Accurate Is This Estimate?
The area math is exact, but the final count is an estimate. Real jobs vary with cut patterns, room shape, and breakage. Treat the result as a close starting point, confirm the box coverage on the actual product, and check quantities with your supplier before you buy.
Sources
Authoritative Sources Used in This Article
This article is for general education only, not professional construction or engineering advice. Material needs vary by product, site, and local building codes, so confirm quantities with your supplier and follow local rules. Reviewed for accuracy by Prof. Dr. Khalil Mudassar, PhD. Last updated September 12, 2026.
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Shakeel Muzaffar is the Founder and Editor-in-Chief of MultiCalculators.com, bringing over 15 years of experience in digital publishing, product strategy, and online tool development. He leads the platform's editorial vision, ensuring every calculator meets strict standards for accuracy, usability, and real-world value. Shakeel personally oversees content quality, formula verification workflows, and the platform's commitment to publishing tools that are genuinely useful for students, professionals, and everyday users worldwide.
