How many tiles do I need for a bathroom floor?

For an 8 ft × 10 ft bathroom (80 sq ft) using standard 12-inch tiles, you'd need about 88 tiles including a 10% waste allowance. Always round up to the nearest full box, and check your specific tile size, since larger or smaller tiles change the count proportionally.

How do I calculate square footage for tile?

Multiply the room's length by its width, both measured in feet, to get square footage. For irregular rooms, divide the space into simple rectangular sections, calculate each section's square footage separately, and add them together for the total.

Does tile size affect how much waste I have?

Yes. Larger tiles generally produce more waste as a percentage in small or irregularly shaped rooms, because each cut tile at the edge wastes a proportionally bigger piece. Smaller tiles are more forgiving in tight or oddly shaped spaces but require more grout lines and more individual pieces to install.

Why does dye lot matter when buying tile?

Tile is manufactured in batches called dye lots, and color or shade can vary slightly between lots even for the identical product. Buying all your tile in one order, from the same lot number, avoids a visible mismatch across the finished floor or wall — a risk that grows if you need to reorder later for a project you underestimated.

How many tiles are in a box?

Tiles per box varies by size and manufacturer — smaller tiles (like 12x12 in) often come 10-15 tiles per box, while larger format tiles (18x18 in or bigger) may come 6-8 per box. Always check the specific product's box coverage in square feet, printed on the box label, to calculate exactly how many boxes to buy.

Tile Calculator

Construction

Calculate tiles needed for a floor

Floor Length (ft)

Floor Width (ft)

Tile Size (inches)

Tile is one of the trickiest materials to estimate correctly because the finished look depends heavily on layout pattern, not just square footage. A straight grid layout wastes relatively little material, but a diagonal or herringbone pattern can waste 20% or more of your tiles to angled cuts at the room's edges. Buying the wrong quantity means either a mid-project store run — with the real risk that your exact tile lot or dye batch is no longer available — or a stack of expensive leftover tile you can't return.

Our tile calculator converts your floor or wall area and chosen tile size into an exact tile count, automatically applying the right waste percentage for your layout pattern. Enter the room's square footage and your tile's dimensions, and the calculator returns both the base tile count and the recommended purchase quantity with waste included.

This works for floor tile, wall tile, and backsplash projects alike — just adjust the area and tile size to match your specific surface.

Why Tile Calculator Matters

Tile is priced per square foot but sold by the box, and most manufacturers use limited production runs called dye lots — meaning tile purchased later to cover a shortfall may not exactly match the color and shading of tile bought earlier, even from the same product line. This makes an accurate initial estimate far more important for tile than for many other materials, since a mid-project reorder carries real risk of a visible mismatch across the finished floor or wall.

The waste factor is also project-specific in a way many other materials aren't. A simple square room with a straight grid layout might only waste 10% of tiles to edge cuts, while a room with a diagonal layout, an irregular shape, or a lot of fixtures to tile around (like a bathroom with a toilet, vanity, and tub) can waste 20% or more. Underestimating this factor is one of the most common tile-buying mistakes, and it directly affects whether you finish the job with matching material or end up patching in a slightly different batch.

The Tile Calculator Formula, Explained

Tiles needed = [Floor area (sq ft) / Tile area (sq ft per tile)] × (1 + Waste %)

First calculate the room's area in square feet (length × width, or the sum of multiple rectangular sections for irregular rooms). Then calculate the area of a single tile in square feet — for example, a 12 in × 12 in tile is 1 square foot, while an 18 in × 18 in tile is 2.25 square feet (1.5 ft × 1.5 ft).

Divide the room area by the single-tile area to get the base number of tiles needed to cover the space with zero waste. This base number is never the real purchase quantity, because some tiles at the room's edges must be cut, and cut pieces are rarely reusable elsewhere in the layout.

Add a waste percentage on top of the base count: 10% for a simple room with a straight grid layout, and 15–20% for diagonal layouts, herringbone patterns, rooms with many corners or fixtures, or large-format tile in a small room where cuts are proportionally more wasteful. Always round the final tile count up to the nearest full box, since boxes cannot be split for purchase.

How to Use the Tile Calculator: Step by Step

Measure the floor or wall area
Measure the length and width of the space to be tiled and multiply to get the total square footage; for irregular rooms, break the space into rectangles and sum each section.
Calculate your tile's area
Multiply your chosen tile's length by its width (converted to feet) to find the area of a single tile.
Divide to find base tile count
Divide the total floor area by the single-tile area to get the base number of tiles needed with no waste factored in.
Add a waste percentage and round to boxes
Add 10% for a simple straight-grid layout, or 15–20% for diagonal patterns, complex rooms, or large-format tile, then round up to the nearest full box based on the tiles-per-box count on the product label.

Tile Calculator Examples: Real-World Scenarios

Bathroom Floor, Straight Layout

An 8 ft × 10 ft bathroom is being tiled with standard 12 in × 12 in floor tile in a simple straight-grid layout.

Room area:80 sq ft (8 × 10)

Tile size:12 in × 12 in = 1 sq ft per tile

Waste:10% (simple layout)

Calculation

Base tiles = 80 / 1 = 80 tiles; with 10% waste = 88 tiles

Result

Buy 88 tiles, rounding up to the nearest full box based on the manufacturer's tiles-per-box count.

Kitchen Floor, Diagonal Layout

A 150 sq ft kitchen is being tiled with 18 in × 18 in porcelain tile installed in a diagonal pattern, which increases edge-cutting waste.

Room area:150 sq ft

Tile size:18 in × 18 in = 2.25 sq ft per tile

Waste:20% (diagonal pattern)

Calculation

Base tiles = 150 / 2.25 = 66.67 tiles; with 20% waste = 80 tiles

Result

Buy 80 tiles. The diagonal layout consumes 13 more tiles than the same room would need in a straight grid, illustrating why layout pattern matters as much as square footage.

Common Mistakes to Avoid

Using a flat 10% waste factor regardless of layout pattern — diagonal, herringbone, and other angled patterns routinely need 15–20% waste, not 10%.
Buying tile from multiple orders without checking the dye lot number, which can result in a visible color or shade mismatch between batches, especially with natural stone or handmade-look tile.
Forgetting grout lines when measuring, which slightly reduces actual tile coverage per square foot on large floors — a minor effect for small tile, but worth padding waste slightly higher for large-format tile with wide grout joints.

Tips & Tricks

Buy all tile for a project in one order from the same dye lot whenever possible, and store a few extra tiles after installation for future repairs, since the exact lot may be discontinued later.
For rooms with lots of fixtures — bathrooms with a toilet, vanity, and tub surround — lean toward the higher end of the waste range (15–20%) even with a straight layout, since fixture cutouts generate extra scrap.

Getting your tile count right the first time protects both your budget and your color consistency across the finished room. Use this calculator before you order, and check our flooring calculator if you're comparing tile against other flooring materials, or our drywall calculator if you're finishing walls around a new tile backsplash.

Tile Calculator — Frequently Asked Questions

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Authoritative References

NACHI — Tile and Flooring Inspection Guide

nachi.org — Home inspector reference on tile and flooring installation standards

Tile Council of North America — Installation Handbook

tcnatile.com — Industry reference for tile installation methods and material standards

External links open in a new tab. OmniCalc.us is not affiliated with these organisations.

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