How to use this tile calculator
- Measure the finished length and width of one rectangular floor or wall. Select a unit beside each value; you can combine feet and inches or metric units without converting them first.
- Add together the area of doors, windows, fixed cabinets or other rectangles that will not be tiled, then enter that total in the opening field. Leave it at zero when the entire surface receives tile.
- Enter the tile face length and width from the product specification. Choose inches, millimetres or centimetres, then add the planned grout joint in its own unit.
- Enter the waste allowance you intend to use, the exact number of tiles in one box and the current price per box. Price can be zero when you only need quantities.
- Read the net area, base estimate and allowance before relying on the whole-box result. Confirm the package count, coverage statement, lot and ordering rules with the seller.
What the tile and box results mean
Gross area is length multiplied by width after unit conversion. The opening area is subtracted once. An opening equal to or larger than the surface is rejected instead of producing a zero or negative order.
One repeating module is tile length plus grout by tile width plus grout. Net area is divided by that module and rounded up. Waste is applied to the base estimate and rounded up again. Tiles needed are divided by tiles per box and rounded up; cost is whole boxes multiplied by the entered price.
This is a material-area model, not an installation drawing. Edge pieces and reusable cuts depend on the starting line, geometry, pattern and installer. The visible allowance and rounding keep that uncertainty separate from the arithmetic.
Formula: net area = length × width − openings; module = (tile length + grout) × (tile width + grout); base tiles = ⌈net area ÷ module⌉; order tiles = ⌈base × (1 + waste % ÷ 100)⌉; boxes = ⌈order tiles ÷ tiles per box⌉.
Worked tile quantity examples
12 ft × 10 ft floor with 12 in tile
With no opening, a 1/8 in grout joint and 10% waste, the net area is 120 ft². The repeating module is 12.125 in × 12.125 in, so the area method gives 118 base tiles. Ten percent waste raises the order to 130 tiles. With 10 tiles per box, buy 13 boxes, or 130 tiles. At 38.50 per box, the estimated tile cost is 500.50 in the same currency. This does not guarantee the edge cuts of a 10-by-12 grid.
Metric wall with a window opening
A 4 m × 2.5 m wall has 10 m² gross area. Subtracting a 1.2 m² window leaves 8.8 m². With 300 mm × 600 mm tile, a 3 mm joint and 12% waste, the area method gives 49 base tiles and 55 tiles after allowance. Six tiles per box means 10 boxes. If each box costs 27, the estimated material cost is 270. Measure reveals, corners and partial-height edges separately before ordering.
Where an area-based estimate helps
Use it for an early quote for a rectangular floor, backsplash, shower wall or feature wall covered by one tile. To compare packages, change tiles per box and price, then record each result.
Split an L-shaped space into non-overlapping rectangles. With the same tile, add material needs before the final box rounding; rounding each section separately can buy extra boxes.
Keep measurements, tile SKU, box count and waste. Compare stated box coverage with this piece-based estimate.
Limits, measurements and common errors
- Rectangular tiles in a regular area estimate only. Herringbone, diagonal, offset, mosaic-sheet and mixed-size patterns are not laid out or assigned an automatic waste rate.
- The opening field subtracts area, not individual cut positions. Small openings may create extra cuts even when their area reduces the estimate. Do not subtract an opening unless it truly receives no tile.
- Nominal tile size can differ from actual manufactured size, and box coverage may use the manufacturer’s own joint assumptions. Use the exact product label and installation specification.
- Waste is a user input, not a safety recommendation. Breakage, pattern, room squareness, skill, spare stock and returns policy can change the suitable amount.
- The estimate covers tile material only. It does not calculate adhesive, grout volume, substrate, trim, labour, structural suitability, waterproofing or code compliance.
- Enter plain non-negative decimals with no unit text or thousands separators. Tile and surface dimensions must be greater than zero, tiles per box must be a whole number, and openings must be smaller than gross area.
Copying and checking your estimate
Copy result creates a short summary of tiles, boxes and cost. Inputs are not saved or sent; reloading or changing language starts a new page. Before buying, keep a note or screenshot with dimensions, units, openings, joint, waste, box count and price. Browser print preserves the result and guide but omits the form. Recalculate after any measurement or product change.
Frequently asked questions
Does grout width reduce the number of tiles?
Here, a positive joint increases the module and can lower the tile equivalent. Real edges lack a full joint and cuts occur by row, so verify the layout.
Why are boxes always rounded up?
A fraction of a box normally cannot be ordered. Rounding down would miss the calculated quantity; extra pieces from box rounding are shown.
Should I subtract a doorway, window or cabinet?
Subtract only the measured area that definitely receives no tile. Do not subtract a doorway when the floor continues through it, and remember that openings can increase cutting even while reducing area.
What waste percentage should I use?
The calculator deliberately does not choose one. Use the product, pattern, geometry, installer and supplier guidance. Complex patterns are outside this tool rather than silently receiving an assumed rate.
Can this plan herringbone or optimize cuts?
No. It does not draw rows, rotate tiles, balance borders or reuse offcuts. Those tasks need the actual layout and are excluded from this area-based purchase estimate.