Plan the tile setout before the first bag of mortar is mixed
A tile quantity estimate can tell you how many square feet or square metres to order, but it cannot tell you whether the finished room will end with a 1-inch strip beside the doorway. This calculator is for that second problem: setting out a straight tile grid, balancing the perimeter pieces and deciding whether the field should be centered on a tile or on a grout joint.
- Compare tile-centered and grout-joint-centered phases
- Show equal perimeter pieces on opposite sides of a rectangular field
- Rotate rectangular tile by 90° and compare the result
- Include the planned grout-joint width in every repeated module
- Flag a minimum edge piece below your chosen sliver threshold
- Generate a scaled layout preview that can also be passed to the PDF renderer
This tool is intentionally a straight-grid setout calculator. It does not pretend that a diagonal, herringbone, running-bond or multi-format pattern can be reduced to the same edge-cut formula.
Tile layout calculator vs tile quantity calculator
Searches for “tile calculator” often mean material quantity. Searches for “tile layout calculator” usually mean grid position, grout spacing, centerlines and the cuts at the perimeter. HomDera keeps those jobs separate so the layout result is not buried under box counts, prices and waste percentages.
Need boxes and purchase quantity instead? Use the Floor Tile CalculatorUse actual tile face size, not only the name on the box
A product sold as 12 × 24 in or 300 × 600 mm may not measure exactly that on the face. Calibrated and rectified products can still have stated manufacturing tolerances. For a layout that is sensitive to the last half inch or few millimetres, measure several tiles from the batch and use the dimension that will control the installed joint spacing.
Inputs that affect the grid
| Input | What it controls | Best practice |
|---|---|---|
| Tile field length and width | The rectangular area the grid must span | Measure the actual finished boundaries that will control the setout |
| Tile length and width | The face size repeated through the field | Use the actual orientation you want to test; auto mode can rotate it |
| Grout joint | The space between adjacent tile faces | Enter the joint you intend to install, not a generic default |
| Perimeter gap | A user-supplied border excluded from the tiled field | Leave it at zero unless your project already defines the required gap |
| Sliver threshold | A visual warning level for a small edge piece | Use it as a planning filter, not as a code or manufacturer rule |
Why a centered tile and a centered grout joint give different cuts
If a perfectly symmetrical layout produces two equally tiny cuts, symmetry has not solved the practical problem. Shift the phase or rotate the tile and compare the new minimum edge piece.
How the balanced-edge formula works
For N physical tile positions across one usable field dimension, there are N − 1 grout joints. When both perimeter pieces are equal, the remaining field is divided between the two edge tiles after the full interior tiles and joints are accounted for.
Equal edge piece =
[field − (N − 2) × tile face − (N − 1) × grout joint] ÷ 2The calculator searches feasible odd and even position counts, rejects phases where the edge piece would be zero or larger than a full tile, and keeps the centered phase with the larger usable perimeter piece. Auto orientation then compares the entered tile direction with a 90° rotation.
Worked US example: 24 × 12 in tile in a 12 × 10 ft field
How should a 24 × 12 in tile be set out in a 12 × 10 ft rectangular area with a 3/16 in grout joint?
Answer: Enter 12 ft × 10 ft for the field, 24 × 12 in for the tile and 3/16 in for the joint. Leave layout and orientation on Auto. The calculator evaluates tile-centered and joint-centered phases on both axes, then compares the tile again after a 90° rotation. The preview shows the selected grid and the exact perimeter pieces produced by that geometry.
Explanation: The best setout is not automatically the one with the fewest tile positions. A slightly different phase can be preferable when it turns an awkward sliver into a wider, easier-to-set perimeter cut.
What the “tile positions” number means
Tile positions are the grid cells that touch the rectangular field. They are useful for understanding rows, columns and how many locations contain a cut. They are not a purchase quantity. A cut tile may provide a reusable offcut for another location, while breakage, pattern selection and spare material can increase the actual order.
Sliver cuts: use a threshold as a warning, not a universal rule
Installers often try to avoid very narrow pieces at exposed walls because they can look accidental and may be awkward to cut and set. There is no single percentage that is correct for every tile, room or system. HomDera therefore lets you choose the warning threshold instead of presenting one-third of a tile as a mandatory standard.
Perimeter gaps and movement joints are not chosen by this calculator
The optional perimeter-gap field changes the usable geometry only when you already know the gap required by your project. The calculator does not determine movement-joint locations, sealant width, waterproofing transitions or manufacturer-specific clearances. Those details belong to the selected installation system and local project requirements.
Floor, shower wall or backsplash: the geometry is the same, the priorities are not
Where the visual priority usually changes
| Surface | What often matters most | Setout check |
|---|---|---|
| Open floor | Balanced cuts at visible walls and through main sightlines | Check the doorway and the longest uninterrupted wall |
| Bathroom floor | Cuts around the doorway, tub, vanity, WC and any floor drain | Treat fixtures and a drain as separate site constraints |
| Shower wall | Relationship to corners, niche, valve trim and ceiling | Do not let a simple wall rectangle hide niche or waterproofing details |
| Kitchen backsplash | Countertop line, cabinet ends, outlets and focal area behind the cooktop | Mock up the centerline against real cabinet dimensions |
Transfer the result to the room
- Mark the real centerlines or reference line on the substrate
- Measure from those lines to both opposing boundaries
- Dry-lay a representative row using the actual spacers
- Confirm that the calculated edge pieces still make sense where walls are out of square
- Decide which visible edge gets priority if the room cannot stay perfectly symmetrical
- Only then lock in the final setting line
A clean SVG grid cannot detect a wall that bows 3/8 in, a doorway that is not square, a drain that must land inside one tile, or a movement joint that cannot be bridged. Use the calculator to choose the setout, then verify the setout on site.
Grout width changes the last cut
The grout joint is part of the repeating module, not an afterthought. A 3/16 in or 3 mm joint repeated across many tiles can move the last grout line enough to change a perimeter cut significantly. That is why this tool includes joint width in the setout arithmetic instead of estimating only from bare tile dimensions.
Once the joint width is chosen, estimate the grout quantity separatelyCommon setout mistakes
Mistake and correction
| Mistake | What happens | Better approach |
|---|---|---|
| Starting with a full tile at the first wall by habit | All of the remainder is pushed to the far wall | Compare centered phases before committing |
| Ignoring grout in the grid math | The error accumulates over every course | Use the actual planned joint width |
| Using nominal tile size without checking the batch | Edge cuts differ from the drawing | Measure representative tile faces |
| Optimizing only for minimum waste | A low-waste layout can still leave an ugly sliver | Score the visible edge cuts as well |
| Treating the preview as a fabrication drawing | Openings, drains and out-of-square walls are missed | Verify the final setout on the real surface |
Pair the layout with the rest of the tile estimate
Once the setout is fixed, material planning becomes easier because you know the orientation and joint width you actually intend to use. Keep purchase quantity, grout and mortar as separate calculations so each result remains transparent.
Estimate thinset or tile adhesive for the selected tile size and areaFrequently asked questions
Should I center a tile or a grout joint in the room?
Compare both. The better phase is usually the one that gives useful perimeter pieces and fits the important sightlines. Auto-balanced mode performs that comparison independently on both axes.
Can I use this for wall tile?
Yes, for a rectangular straight-grid field. Enter wall width and height as the two field dimensions. Treat niches, windows, shelves, outlets and changes of plane as separate layout constraints.
Does the calculator support 50% running bond or one-third offset?
Not in this version. Alternating-row offsets change the edge cuts row by row and deserve a dedicated pattern model. This calculator stays exact for straight stack-bond geometry instead of applying a misleading blanket waste percentage.
What does rotate 90° change?
For rectangular tile, rotation swaps which tile face runs along each field axis. That can change both the number of positions and the perimeter cut widths even though the tile area is unchanged.
Can I order tile from the position count?
No. Use the grid to plan the layout, then use the separate Floor Tile Calculator for purchase quantity, boxes and a waste allowance. Layout pieces and purchasing units are intentionally not treated as the same number.
HomDera provides layout geometry for planning. Confirm substrate condition, movement accommodation, waterproofing, product tolerances, joint requirements and the final setting lines for the actual installation before tile is fixed.