CalcPro

Tile Calculator

Tiles and boxes needed to cover an area, including a waste allowance.

What this calculator does

Before you buy materials for a tiling project, you need to know exactly how many tiles to order—and how many boxes that means. This calculator tells you both, accounting for the waste that naturally occurs during cutting and installation. It's designed for square tiles and lets you set your own waste percentage based on the complexity of your layout.

The formula

(Area length × Area width × 144) ÷ Tile size² × (1 + Waste % ÷ 100) ÷ Tiles per box

Breaking this down: you convert your floor or wall dimensions (in feet) to square inches by multiplying by 144, then divide by the area of one tile in square inches. This gives you the base number of tiles needed. Then you apply the waste allowance as a multiplier, and finally divide by the number of tiles per box to get your box count.

Worked example

Imagine you're tiling a bathroom floor that's 10 feet long and 8 feet wide. You've chosen 4-inch square tiles, and your supplier sells them 25 tiles per box. You're planning a straightforward layout with minimal cuts, so you'll use a 10% waste allowance.

Step 1: Calculate total area in square inches

  • 10 ft × 8 ft = 80 square feet
  • 80 × 144 = 11,520 square inches

Step 2: Find the area of one tile

  • 4 inches × 4 inches = 16 square inches

Step 3: Calculate base tile count

  • 11,520 ÷ 16 = 720 tiles

Step 4: Add waste allowance

  • 720 × (1 + 10 ÷ 100) = 720 × 1.10 = 792 tiles

Step 5: Convert to boxes

  • 792 ÷ 25 = 31.68 boxes
  • Round up to 32 boxes

You'd order 32 boxes, giving you 800 tiles total—enough to cover the floor with spare tiles for future repairs or breakage during installation.

Common mistakes to avoid

Underestimating waste: Many DIYers use 5% waste, but that's realistic only for very simple layouts with few cuts. If your bathroom has a toilet flange, corners, or an irregular shape, jump to 15–20%. Complex mosaics or diagonal patterns warrant 25% or more.

Forgetting to round up: Always round your box count up, never down. Ordering 31.68 boxes means you need 32; you can't buy 0.68 of a box, and running short mid-project is expensive and frustrating.

Mixing tile sizes: This calculator works for one square tile size at a time. If you're using a mix—say, 4-inch tiles for the main area and 2-inch accent tiles for a border—calculate each section separately and add the results.

Ignoring grout lines: The calculator assumes tiles are laid edge-to-edge. If you're using wide grout lines (more than 1/8 inch), you may need slightly fewer tiles, but it's safer to stick with the calculated amount; the difference is usually negligible and you'll have backups.

Not checking box contents: "Tiles per box" varies wildly between products. A 12-inch tile might come 8 to a box, while a 2-inch tile might come 100 to a box. Always verify on the product label or with your supplier before calculating.

Frequently asked questions

What waste percentage should I use?

For simple rectangular layouts with few cuts, 10% is standard. Increase to 15–20% if you have corners, obstacles, or an irregular shape. Complex patterns, diagonal layouts, or mosaic work may need 25% or more. When in doubt, go higher—extra tiles are useful for future repairs.

Can I use this for wall tiles?

Yes. Measure the wall length and width in feet and enter them the same way. Just make sure you're measuring only the area you want to tile (for example, if you're tiling from the floor to 5 feet up, use 5 as the height).

What if my tiles aren't square?

This calculator is designed for square tiles only. If you have rectangular tiles, multiply length × width to get the area of one tile (in square inches), then divide your total area by that number. You'll need to do the math separately or use a different tool.

Why should I round up the box count?

Because you can't buy a partial box. If the calculator shows 31.68 boxes, you physically need to purchase 32. Rounding down leaves you short, and reordering later often means paying more for shipping or finding the product is discontinued.

Does this account for grout lines?

No—the calculator assumes tiles are laid edge-to-edge or with very thin grout lines (1/8 inch or less). Thick grout lines reduce the number of tiles needed slightly, but the difference is small and it's safer to have extra tiles on hand.

Can I return unused boxes?

Most tile suppliers accept returns within 30 days if boxes are unopened and in original condition. Always check the store's return policy before buying, and keep your receipt. Dye lots can vary, so buying a few extra now is cheaper than trying to match them later.

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