Calculation method
Divide the field area by the repeating cell (actual tile length + joint) × (actual tile width + joint). Apply the selected layout allowance and round up to whole tiles. Divide by tiles per box, or infer whole tiles per box by flooring labelled box coverage divided by actual tile-face area. Divide required tiles by that whole count and round up to boxes. This is an area estimate, not a cutting layout.
Worked example: input to purchase quantity
A 10 × 10 ft field (3.048 × 3.048 m), 12 × 12 in tiles (30.48 × 30.48 cm) and 1/8 in joints (0.3175 cm) need 108 tiles with 10% extra, or 11 boxes of 10. Selecting diagonal and 15% extra needs 113 tiles and 12 boxes.
Plan a tile field before ordering cartons
This calculator estimates individual rectangular tiles and unopened boxes for a floor or wall. It combines the area being tiled, the actual face dimensions, the planned grout joint, and the selected cutting allowance. Its installed cell is one tile length plus one joint by one tile width plus one joint. That repeating cell is an area approximation for a field of identical tiles. It does not draw the first row, allocate every perimeter cut, or decide whether two offcuts can share one tile.
Enter a positive direct area when you have already measured several wall sections or an irregular floor. That area takes precedence over the length and width entries. Leave direct area at zero to use the rectangular dimensions instead. Zero is an explicit unused value, not a missing measurement. For several surfaces, add only areas receiving the same tile, pattern, joint, and allowance. A shower floor mosaic and a bathroom wall field should normally have separate estimates because their products and cutting problems differ.
Use actual tile faces and the specified joint
A tile advertised as twelve inches square may have a smaller measured face. Read the current product specification or measure a representative sample. Do not enter a nominal module and then add the grout joint again. Conversely, do not remove the joint from an actual face dimension. Rectified edges, handmade variation, installation tolerances, and substrate movement affect joint selection. The calculator accepts a zero joint for arithmetic comparison, but that input does not endorse a jointless installation. Follow the tile and setting-system instructions.
The perimeter of a finite room does not contain a full additional joint after every tile. This model spreads the repeating module across the measured area and therefore cannot guarantee a small room's exact piece count. Draw rows and check narrow border cuts before buying. Large tiles, diagonal boundaries, niches, angled walls, and aligned patterns can use considerably more pieces than an area estimate suggests. Mosaic sheets, mixed-size patterns, trim strips, and decorative borders require their own packaging and layout calculations.
Keep layout waste visible
The straight and diagonal selectors use separate editable allowance entries. The initial values are ten and fifteen percent. Geon Tile describes ten to fifteen percent as general overage guidance for cutting and handling. Assigning the lower value to straight work and the higher value to diagonal work is this tool's planning convention, not a manufacturer guarantee for either pattern. Replace both entries when your supplier or installer has a project-specific takeoff. Changing the selected layout chooses one percentage; it does not add the two percentages together.
Keep spare repair tiles in the same allowance or on a separate written line so they are not counted twice. A box ordered later may differ in shade, caliber, finish, or availability. Inspect cartons before installation and follow the seller's batch guidance. Broken pieces found on delivery should be reconciled with the order rather than quietly absorbed into an already tight cutting budget. Save the dimensions and percentage used so a revised plan can be traced.
Convert pieces to the package actually sold
If pieces per box is positive, it must be a whole number and controls the package calculation. The box-coverage entry is then ignored. To use labelled area instead, set pieces per box to zero and enter a positive box coverage. The calculator divides label coverage by one actual tile face and floors that ratio to whole tiles per box. It then divides required pieces by that conservative box count and rounds boxes up. A 10.8-square-foot package basis with one-square-foot tiles is treated as ten whole tiles, never a fractional eleventh tile. This keeps grout area out of the package's ceramic-face quantity. Verify whether the label uses actual faces or an installed module; the two bases must agree.
US mode uses feet for room dimensions, inches for tile and joint dimensions, and square feet for area. Metric mode uses metres, centimetres, and square metres. Switching units converts existing values, including carton coverage. The estimate excludes adhesive, underlayment, waterproofing, grout volume, spacers, movement joints, tools, and labor. Use the separate grout calculator for a different material quantity, and finish with a dry layout rather than treating the carton total as an installation plan.
Product and method reference
Reference limits and default yields are identified separately from user-entered values; verify the adopted local code and current product label. Geon Tile overage guidance.
Calculation and editorial review: November 3, 2026. Arithmetic runs in your browser; project inputs are not submitted to TwoCut.