How to Calculate Sq Ft for Tile

This calculator works out the total square footage you need to buy for a tiling project. You enter the length and width of the room (or the area to be tiled) in feet and inches, plus the size of the tile you plan to use, and it returns the area in square feet, the number of tiles required, and an extra 10% waste allowance so you don’t run short.

Formula

The basic formula for square footage is:

Area (sq ft) = Length (ft) × Width (ft)

For tiles, you also need the area of one tile in square feet:

Tile Area (sq ft) = (Tile Length in inches × Tile Width in inches) ÷ 144

Then the number of tiles is:

Tiles = Ceiling(Area ÷ Tile Area)

Add 10% for waste and breakage:

Tiles with Waste = Ceiling(Tiles × 1.1)

Variables:

• Length – the room or area length in feet (ft)
• Width – the room or area width in feet (ft)
• Tile Length – the tile length in inches (in)
• Tile Width – the tile width in inches (in)
• Area – the total floor or wall area to be tiled in square feet (sq ft)
• Tile Area – the surface area of one tile in square feet (sq ft)
• Tiles – the number of whole tiles needed (rounded up)

Worked Example

Using the default values from the calculator: a room 12 ft long by 10 ft wide, with 12×12 inch tiles.

1. Room area: 12 ft × 10 ft = 120 sq ft
2. Tile area: (12 in × 12 in) ÷ 144 = 144 ÷ 144 = 1 sq ft
3. Tiles needed (no waste): 120 sq ft ÷ 1 sq ft = 120 tiles
4. With 10% waste: 120 × 1.1 = 132 tiles

The calculator shows: area 120.00 sq ft, tile area 1.0000 sq ft, tiles 120, and tiles with waste 132.

When to Use This Calculation

Use this whenever you are buying tile for a floor, wall, backsplash, or countertop. It gives you a reliable estimate for ordering materials. Always round up to the nearest full tile because you cannot buy a fraction of a tile, and you will need to cut pieces at edges, around fixtures, and for corners.

How to Read the Result

The first number is the total area you need to cover. The second is the area of one tile. The third is the minimum number of whole tiles that will cover that area if you could cut perfectly with zero waste. The fourth is the realistic number to buy, including a 10% buffer for cuts, breakage, and future repairs. If the result is not a whole number, you must round up – never down.

Common Mistakes

• Mixing units – Forgetting to convert inches to feet. Always divide inch measurements by 12 to get feet, or use the tile area formula above.
• Forgetting waste – Buying exactly the area without extra tiles. You will likely need extra for cuts and breakage.
• Rounding down – Rounding the number of tiles down to avoid buying an extra box. This leaves you short.
• Ignoring grout lines – Grout lines reduce the number of tiles slightly, but it’s safer to ignore them and keep the 10% waste.
• Measuring only the longest and widest points – For L-shaped rooms or areas with obstacles, measure each rectangular section separately and add them.

Tips

• Measure in feet and inches for accuracy. Convert inches to feet by dividing by 12 (e.g., 6 inches = 0.5 ft).
• For irregular shapes, break the area into rectangles, calculate each, and sum them.
• Add 10% waste for straight layouts. For diagonal layouts or rooms with many corners, add 15–20%.
• If you are tiling a wall, measure the wall area (width × height) and subtract any large openings like doors or windows.
• Always buy from the same dye lot (box label) to ensure color consistency.
• Keep a few extra tiles in storage for future repairs – they may no longer be made later.

Troubleshooting

My room is not a perfect rectangle. Divide it into rectangles, calculate each, and add the areas together. For triangles, use (base × height) ÷ 2.

The calculator gives a fractional number of tiles. That’s normal. Always round up to the next whole number. For example, 120.3 tiles means you need 121 tiles.

I have a very large area and the number of tiles seems too high. Double-check your measurements. One common error is measuring in inches but entering feet. For example, a room that is 144 inches long should be entered as 12 ft, not 144 ft.

My tile is not square. The calculator handles any rectangular tile as long as you enter its length and width in inches. For non-rectangular tiles (like hexagons), use the actual area of one tile in square inches and divide by 144 to get square feet.

I want a 15% waste instead of 10%. Multiply the tiles needed by 1.15 instead of 1.1. The calculator’s 10% is a standard baseline; adjust upward for complex layouts.

Frequently Asked Questions

How do I convert inches to feet for the formula?

Divide the number of inches by 12. For example, 18 inches = 18 ÷ 12 = 1.5 feet.

What if my room is measured in meters?

Convert meters to feet first: 1 meter = 3.28084 feet. Or use the same logic: area in square meters × 10.7639 = square feet.

Should I include the grout line in my tile area?

No. Grout lines are small and usually less than 1/4 inch. Including them would slightly reduce the tile count, but it’s safer to ignore them and rely on the waste allowance.

How much extra tile should I buy?

For a standard straight layout, 10% extra is enough. For diagonal layouts or lots of cuts, buy 15–20% extra. If the tile is expensive or hard to find, consider buying even more.

Can I use this for wall tiles?

Yes. Measure the wall height and width just like a floor. For walls with windows or doors, subtract those areas, but keep the waste percentage to cover the cutouts.

What if my tile is sold by the box and not individually?

Check the box label for the square footage it covers. Then divide your total area (including waste) by that number and round up to the nearest whole box.

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in len | Length | ft | 12 | 0
in wid | Width | ft | 10 | 0
in tile_len | Tile Length | in | 12 | 0
in tile_wid | Tile Width | in | 12 | 0
out area | Area to tile | sq ft | len * wid | 2
out tile_area | Tile area | sq ft | (tile_len * tile_wid) / 144 | 4
out tiles | Tiles needed (no waste) | tiles | ceil(area / tile_area) | 0
out tiles_waste | Tiles with 10% waste | tiles | ceil(area / tile_area * 1.1) | 0