Tile Layout & Border Cut Calculator
Enter the surface, tile, grout, and perimeter gap dimensions to lay out a centered straight grid. The calculator compares orientations, avoids narrow edge slivers when the span allows it, and returns border cut sizes and starting offsets.
Recommended orientationLength across surface
- Left and right border cuts
- 23.5
- Top and bottom border cuts
- 11.31
- Smallest border as a full-tile percentage
- 94.27%
- Uncut field tiles
- 18
- Border and corner pieces
- 22
- First full-tile start from left
- 23.88
- First full-tile start from bottom
- 11.69
- Tiles to order
- 44
- Layout summary
- Length across surface: 3 full columns by 6 full rows, 23.5 in equal side cuts, 11.313 in equal end cuts, 0.125 in grout, first full tile starts 23.875 in from the left and 11.688 in from the bottom.
Perimeter gaps are removed before the centered tile grid is calculated.
Exact-fit axes have no border cut; their first full tile starts at the perimeter gap.
Order quantity is area-based and does not optimize reuse of cutoffs.
How to use this calculator
- Measure the surface width and length at the edges you intend to tile.
- Measure the actual tile face in both directions instead of relying only on nominal size.
- Enter the planned grout joint and the movement or perimeter gap left at each edge.
- Choose an orientation or let the calculator compare both directions.
- Review the border cuts, first full-tile starts, and area-based order quantity.
How the centered layout is calculated
This calculator applies the balanced straight-grid layout method used by tile setters before snapping control lines. It first removes the perimeter clearance from each side, then centers a run of full tiles and grout joints in the remaining usable span. The same procedure is applied independently across the width and length.
Let W and L be the measured surface dimensions, E the perimeter gap per side, G the grout joint, and A and B the measured tile dimensions. The usable spans are:
Ux = W - 2E and Uy = L - 2E
For one axis, let U be the usable span, T the tile size in that direction, and P = T + G the pitch. If (U + G) / P is an integer within 0.01 inch of the span, the axis is treated as an exact fit with full tiles only. Otherwise the calculator starts with n = floor((U + G) / P) full interior tiles and computes equal border cuts:
c = (U - nT - (n + 1)G) / 2
If that centered result makes a cut smaller than half a tile, one full interior tile is removed and the cut is recalculated. That is the usual way to trade one extra full tile for larger, more workable edge pieces. If the usable span is smaller than one tile, the result is one trimmed piece for that axis with no internal grout joint.
How orientation is chosen
Automatic mode checks the tile as entered and rotated 90 degrees. Each orientation receives a score equal to the smaller border fraction: min(width cut / oriented tile width, length cut / oriented tile length). Exact-fit axes count as a full fraction because they have no border sliver. The higher score wins; if both are tied, the calculator chooses the orientation with fewer border and corner pieces.
What moves the result most
Small changes in perimeter clearance, grout width, or actual tile size can move the starting line enough to change the border cut. Rectangular tile can also behave very differently when rotated, especially in rooms where one direction is close to a whole number of tile pitches. Measure several tiles from the boxes you will install, because calibration and warpage ranges can shift the chalk lines.
What the calculator leaves out
The layout assumes a rectangular, unobstructed surface and a straight stack-bond grid. It does not place joints around doorways, cabinets, niches, columns, drains, movement joints, transitions, or focal points. It also estimates order quantity from usable area plus the selected allowance; it does not pair complementary offcuts or predict breakage, shade selection, or installer-specific waste.
Worked example
Suppose a floor is 120 inches wide by 96 inches long, the actual tile is 12 by 24 inches, the grout joint is 1/8 inch, the perimeter gap is 1/4 inch per side, and the extra tile allowance is 10%.
The usable surface is 119.5 by 95.5 inches. With the tile rotated so the 24 inch side runs across the width, the width axis starts with four full tiles but the edge cuts would be less than half a tile, so it drops to three full columns and gives (119.5 - 3 × 24 - 4 × 0.125) / 2 = 23.5 inch side cuts. The length axis drops from seven to six full rows and gives (95.5 - 6 × 12 - 7 × 0.125) / 2 = 11.3125 inch end cuts.
The smallest border is about 94.3% of a full tile side, the first full tile starts 23.875 inches from the left and 11.6875 inches from the bottom, and the area-based order quantity is 44 tiles.
Common questions
Should tile be centered on the room or on the main visible area?
Center on the area that controls the finished appearance. In a simple open room that is usually the room itself, but a shower wall, hallway, doorway, tub, island, or main sight line may deserve its own layout reference.
How do I avoid narrow sliver tiles along a wall?
A common method is to center the layout, check the edge cuts, and remove one full tile from the interior run if the border would be less than half a tile. That produces larger equal cuts at opposite edges when the surface span allows it.
Do grout joints count when laying out tile?
Yes. The installed pitch is the tile size plus the planned grout joint. Grout joints also sit between border cuts and the first full tile, so leaving them out can shift the starting line and make the last cut wrong.
Should I rotate rectangular tile to get better edge cuts?
Often it is worth checking. Rotating a rectangular tile changes both axis pitches, and one orientation can produce much larger edge pieces or fewer cut positions than the other.
Where should the first tile or chalk line start?
When there is a border cut, the first full tile starts one perimeter gap plus the border cut plus one grout joint from the edge. On an exact-fit axis, the first full tile starts at the perimeter gap because there is no border piece before it.
Can this calculator handle an L-shaped room or staggered pattern?
No. Use it for one rectangular straight-grid area at a time. L-shaped rooms, running-bond patterns, diagonal layouts, drains, and focal-point alignments need a separate layout sketch or installer plan.