Tile Calculator: How Many Tiles Do I Need?
Work out how many tiles and boxes a floor or wall needs from the area and tile size, with grout gap, waste and cost. Add or subtract rectangles, pick the layout, and take the tile count and a grout estimate to the supplier or the quote.
Your numbers
Areas to tile
Up to 6 rectangles. Subtract the parts you will not tile: a vanity, a tub, a kitchen island.
Tile
The spacer size.
For the grout only. Check the box.
Waste
Typical for a straight layout: 10 %. Cuts at the walls, breakage and spares for repairs.
Boxes and price
From the box label or the price tag.
Grout estimate
1.9 kg/L is Sika's figure for its cement grout. Use your grout's data sheet.
Tiles to buy
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- Boxes
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- Area to tile
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- Tiles without waste
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- Tile area bought
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- Tile cost
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- Grout, about
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An estimate for quoting and ordering. Buy every box from the same lot, and keep a few spare tiles for repairs.
Grout is the data sheet's theoretical amount with no waste; buy a little more. Setting materials, membrane and trim are not included.
The calculation runs in your browser and ParrotNotes does not store your numbers. They sit in the page address so you can bookmark or share the result.
How many tiles do I need?
Measure the floor or wall in feet and work out the square feet; split an L-shaped room into rectangles and subtract what you will not tile, such as a vanity or a tub. Each tile takes up its own size plus one grout joint, so divide the area by (tile length + joint) × (tile width + joint), then add the extra for cuts and breakage and round up.
Worked example: a 12 × 10 ft kitchen is 120 sq ft. A 12 × 24 in tile with a 1/8 in joint takes up 12.125 × 24.125 in, or 2.03 sq ft. That is 59.07 tiles; with 10 % extra, 65 tiles. At 8 tiles a box, buy 9 boxes.
How much extra tile to buy for each layout
There is no single rule for overage, but trade rules of thumb agree that patterns with angled cuts waste more. The calculator starts at 10 % for a straight layout, 15 % for diagonal and 20 % for herringbone, and labels them typical: change them to what your installer uses. Small rooms, lots of corners and large-format tile push the number up.
Buy every box from the same lot, and leave the spares with the customer. A tile that matches a cracked one is hard to find a few years later.
How much grout do I need?
Grout fills the joints, so the amount depends on the joint width, the tile thickness and how much joint there is per square foot: small tiles have far more. Sika's data sheet for its SikaCeram-638 grout gives the theoretical consumption as joint width × tile thickness × (tile length + tile width) ÷ (tile length × tile width) × density. Worked in millimetres, the result is kilograms per square metre: a 30 × 30 cm tile, 1 cm thick, with a 3 mm joint needs about 0.38 kg per m², the figure in Sika's own table.
The calculator uses that formula with Sika's density of about 1.9 kg/L and converts to pounds. It is a theoretical figure with no waste, so round up to the next bag, and use the density on your grout's data sheet if it differs.
Tips for the site visit
Measure each area on its own, and note what changes the job: the subfloor or wall the tile goes on, a floor that has to come up first, a shower that needs a membrane, the thresholds and trim. The tile maker's installation instructions and your local code decide how it is set.
Then write down what the customer told you: the tile they chose, the pattern, where they want the cuts to land, which room first and the deadline. Those notes decide the quote as much as the box count does.
Sources, checked October 2026. All figures are estimates:
More for flooring, tile and building-materials sales: Distributor sales, Building materials sales, Construction daily report.
The box count is only part of the quote
The tiles go on the quote. What the customer said on the visit about the tile they picked, the pattern, where the cuts should land, the floor that has to come up first and the deadline goes in ParrotNotes: record the visit and get the summary and next steps.
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