Tiles Used vs Tiles Consumed
The tile layout planner labels its count “Tiles used”: whole tiles plus cut pieces. This is also the number of new tiles consumed before reserve. Each cut piece consumes one whole new tile, even when two pieces could be cut from the same tile on site. The planner does not reuse offcuts.
Its consumed count is therefore at least the number of source tiles you would need with successful offcut reuse. A small edge piece still counts as one consumed tile. “Tiles to buy” adds spare tiles to that count; it is a separate result.
The tile calculator divides net area, including its selected allowance, by one tile’s face area and rounds up. It does not place individual tiles or work out which pieces meet the walls.
Cutting Waste vs Extra Reserve
The planner’s offcut percentage measures material left over after cutting: (allocated tile face area − laid tile face area) ÷ allocated tile face area × 100. Allocated area is the “Tiles used” count multiplied by one full tile’s face area. Laid area includes only the clipped tile faces, leaving out grout joints and perimeter gaps. Spare tiles and box rounding do not enter this percentage.
Extra reserve is added after those cut pieces have been counted. The planner defaults to 5% for spares, such as breakage or a later repair. Adding a second cutting allowance on top would count cuts twice.
The area calculators have no cut layout to count, so their percentage allowance covers cuts and extra tile together. Defaults are 10% for straight lay, 12% for half or third offset, and 15% for diagonal. Herringbone and shower-floor estimates also default to 15%. You can change the allowance for your project; these are calculator defaults, not measured waste rates.
Keep spare tiles from the same batch or dye lot for repairs. Check the box labels when buying them, so a later replacement does not depend on finding a matching batch.
Why Your Calculator Gives a Different Number
Compare the method and settings before comparing totals. Area estimates do not locate cuts. A layout calculation responds to tile direction, starting point, joint width and perimeter gap. The area tile calculator does not subtract grout joints from its tile count. Other calculators may use different default allowances or show a whole-box order as their headline number.
Here is the same 12 × 10 ft room with 12 × 24 in tile in straight lay. Each tile has a 2 sq ft face. In the planner, the 24 in edge runs along the 12 ft room length, a grout joint is centered in both directions, joints are 1/8 in and the perimeter gap is 1/4 in. No offcuts are reused. Neither tile count below includes box rounding.
| Method | Calculation | Tiles to buy |
|---|---|---|
| Area calculator | 120 × 1.10 ÷ 2, rounded up | 66 |
| Layout planner | 32 whole + 28 cuts = 60; × 1.05, rounded up | 63 |
The planner reports 2.1% offcut material and adds 3 spare tiles. The area calculator allows 10% over net area; the planner adds 5% after counting the cuts. These percentages describe different steps. With a 10% planner reserve, this particular layout would also give 66 tiles; that agreement does not mean the methods always match.
Change the starting point or pattern and the edge pieces can change. The tile layout pattern comparisons hold room size, tile size and spacing constant to show that effect.
When Offcuts Can Be Reused
In straight or offset rows, a piece left after cutting one end may fit the opposite end or a later row. Compare the usable offcut with the required piece in both dimensions, allowing for the material removed by the saw blade. An offset changes the required end length from row to row; a leftover that fits one row may not fit the next.
The face direction and edge finish must also work. Keep a cut edge where the installation detail permits it, such as beneath perimeter trim. If an edge will remain visible, check whether it needs a factory glaze or a specified ground or finished edge. A sawn edge does not automatically match the tile’s glazed or rectified factory edge.
Confirm reuse with a dry layout and cutting list before reducing the order. Because the planner assigns a fresh tile to every cut piece, its count is conservative about reuse; it does not credit those savings.
How Boxes Round Your Order Up
When buying by piece count, divide tiles to buy by pieces per box and round up to a whole box. With 66 tiles and eight per box, 66 ÷ 8 gives 9 boxes after rounding: 72 tiles, or 144 sq ft. That is 12 sq ft beyond the area calculator’s 132 sq ft including allowance. The original 66-tile estimate stays the same; the box order supplies more.
If you enter coverage per box instead, the area calculator divides area including allowance by that coverage and rounds up. The planner first converts its tile order, including reserve, into full-tile area before dividing by box coverage. Use the coverage printed on your box.
For mosaics sold on sheets, use the actual coverage of one sheet, not the size of each small tile. Round the required sheets up, then divide by sheets per box and round up again if buying full boxes. Full-box overage is separate from the allowance you entered.