Should I center a tile or a grout joint on the centerline?

Whichever leaves the larger cuts at the walls. The two options move the whole layout by half a tile, so when one leaves a sliver the other usually does not. For a 12 ft (144 in) room with 12 in tiles and a 1/8 in joint, a centered tile leaves 5 1/4 in cuts and a centered joint leaves 11 5/16 in cuts. The calculator's comparison line shows both for each direction. A common installer tip, repeated by the Ceramic Tile Education Foundation, is to shift from the center of a tile to the center of a joint when the cuts are small.

How small can an edge cut be?

ANSI A108.02 says usually no cuts smaller than half size should be made, and to center and balance the tile if possible. That is the default flag here. It is a guideline about appearance, and "usually" and "if possible" are in the wording: a narrow cut is not a defect in itself. Some installers accept a third of a tile; that figure is a typical one and not from the standard, so check it against your installer or tile maker. Thin cuts are also harder to cut cleanly and more likely to chip.

Why do I enter the layout direction by direction?

The layout across the length and across the width are independent: each has its own tile size (a 12 × 24 tile is 12 in one way and 24 in the other), its own centerline and its own cuts. Enter the length and the width, and the tile size along each. Leave the width empty to look at one direction only.

Where do I snap the centerline?

Half way along each dimension, measured from the same wall on each end to check the room is square, then snap a chalk line. For a centered tile, set a tile so the line runs through its middle. For a centered joint, set the grout joint on the line. Work out from the center; do not start at a wall. Checking the layout against the doorway, so that the cut rows do not show first, can change the answer; the calculator does not look at that.

Do I count the wall gap?

The calculator takes the dimension as the edge the tile meets. Tile installations usually leave a perimeter movement joint (see the TCNA Handbook movement joint guidelines, EJ171, and your tile setting product’s instructions), which the baseboard or sealant then covers. Subtract that gap from each end of the dimension before you type it, or the cuts will come out too wide by the gap.

Is this for brick-offset or herringbone patterns?

No. The calculator lays tiles in a straight grid. An offset pattern shifts every other row, so the ends of the rows have two different cuts, and a diagonal lay is worked at 45 degrees. Use the numbers as a first guide only for those.

How many tiles should I buy?

This calculator only shows the layout. Use the tile calculator for the quantity, with the overage for your pattern, and the grout and thinset calculators for the rest.

What if the tile is bigger than the room dimension?

A centered tile needs the tile to be no longer than the dimension; otherwise the calculator says so, since every tile would be a cut. For a full tile at a wall, zero full tiles and one cut of the whole dimension are shown.

Tile Layout Calculator: Centered Layout and Edge Cuts

A 12 ft room with 12 in tiles and a 1/8 in grout joint, tile centered on the centerline, gives 11 full tiles across the length, an edge cut of 5 1/4 in at each wall. That 5 1/4 in cut is under half a tile (6 in), a common aesthetic guideline and not a rule. Centering a grout joint instead gives 10 full tiles across the length, an edge cut of 11 5/16 in at each wall. This calculator shows the layout along each direction; the tile calculator counts how many tiles to buy.

Figures based on the sources listed belowUpdated 2026-10-06How we calculate

Room length (first direction)

Room width (second direction, optional)

Layout startWhere the row starts. Centering puts equal cuts at both walls; a full tile at a wall leaves one cut, at the far wall. The comparison line always shows the two centered options side by side.

Tile size along the length

The tile’s actual size in the direction of the room length, measured, not the nominal size. Enter in any unit.

Tile size along the width

The tile’s actual size in the direction of the room width. A 12 × 24 tile is 12 along one direction and 24 along the other. Only used when you enter a width.

Grout joint

The grout joint width. 1/8 in is 0.125 in or about 3 mm.

Flag cuts smaller thanA common aesthetic guideline, not a rule: ANSI A108.02 says usually no cuts smaller than half size. Some installers accept a third.

11 full tiles across the length, an edge cut of 5 1/4 in at each wall

Full tiles, length: 11 tiles, an edge cut of 5 1/4 in at each wall
Edge cuts, length: 5 1/4 in (5.25 in, 133 mm) at each wall, under half a tile (6 in): a common guideline is to shift the layout
Centered tile or joint, length: centered tile 5 1/4 in (5.25 in, 133 mm), centered joint 11 5/16 in (11.31 in, 287 mm): the centered joint leaves the larger cuts
Full tiles, width: 3 tiles, an edge cut of 23 3/4 in at each wall
Edge cuts, width: 23 3/4 in (23.75 in, 603 mm) at each wall
Centered tile or joint, width: centered tile 23 3/4 in (23.75 in, 603 mm), centered joint 11 11/16 in (11.69 in, 297 mm): the centered tile leaves the larger cuts

Shopping list

Chalk line
Tile spacers (1/8 inch)
Laser level
Manual tile cutter
Tape measure with 1/16 in marks

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Edge cuts for common room widths, 12 in tile direction (12 × 12 and the short side of 12 × 24)

Tile 12 in along the dimension, 1/8 in grout joint, worked by this calculator. Cut at each wall to the nearest 1/16 in. * marks a cut under half a tile (6 in), a common aesthetic guideline, not a rule.
Room dimension	Centered tile (full tiles, cut each side)	Centered joint (full tiles, cut each side)	Larger cuts
5 ft	3 full, 11 3/4 in	4 full, 5 11/16 in *	Centered tile
6 ft	5 full, 5 5/8 in *	4 full, 11 11/16 in	Centered joint
8 ft	7 full, 5 1/2 in *	6 full, 11 9/16 in	Centered joint
10 ft	9 full, 5 3/8 in *	8 full, 11 7/16 in	Centered joint
12 ft	11 full, 5 1/4 in *	10 full, 11 5/16 in	Centered joint
14 ft	13 full, 5 1/8 in *	12 full, 11 3/16 in	Centered joint
16 ft	15 full, 5 in *	14 full, 11 1/16 in	Centered joint

Edge cuts for common room widths, 24 in tile direction (the long side of 12 × 24)

Tile 24 in along the dimension, 1/8 in grout joint, worked by this calculator. Cut at each wall to the nearest 1/16 in. * marks a cut under half a tile (12 in), a common aesthetic guideline, not a rule.
Room dimension	Centered tile (full tiles, cut each side)	Centered joint (full tiles, cut each side)	Larger cuts
5 ft	1 full, 17 7/8 in	2 full, 5 13/16 in *	Centered tile
6 ft	1 full, 23 7/8 in	2 full, 11 13/16 in *	Centered tile
8 ft	3 full, 11 3/4 in *	2 full, 23 13/16 in	Centered joint
10 ft	3 full, 23 3/4 in	4 full, 11 11/16 in *	Centered tile
12 ft	5 full, 11 5/8 in *	4 full, 23 11/16 in	Centered joint
14 ft	5 full, 23 5/8 in	6 full, 11 9/16 in *	Centered tile
16 ft	7 full, 11 1/2 in *	6 full, 23 9/16 in	Centered joint

Methodology & assumptions

The layout is worked along one direction at a time, in inches. Let L be the room dimension, t the tile size in that direction, j the grout joint and p = t + j the pitch of one tile and one joint. Full tile at a wall: tiles start flush with one wall, n = floor((L + j) ÷ p) full tiles fit, and the cut at the far wall is L − n × p (the joint in front of it is already counted). Tile centered on the centerline: the middle tile spans L ÷ 2 ± t ÷ 2, so each side has s = (L − t) ÷ 2 left; m = floor(s ÷ p) full tiles fit on each side, the cut on each side is s − m × p − j, and the row has 2m + 1 full tiles. Grout joint centered on the centerline: each side has s = (L − j) ÷ 2 with a tile against the joint, m = floor((s + j) ÷ p) full tiles fit on each side, the cut is s − m × p, and the row has 2m full tiles. A cut that comes out at zero (or a remainder narrower than one joint) means the row ends flush: no cut. The two centered options are compared by the narrower end of each row; a row with no cut counts as the best case, and cuts within 1/32 in of each other are called the same. A cut is flagged when it is narrower than half a tile (or a third of a tile, if you pick that) of the tile size in that direction. Half a tile follows the wording in ANSI A108.02 (usually no cuts smaller than half size); a third is a rule of thumb some installers accept, and is not from the standard. Neither is a pass or fail test: it is an appearance guideline, and the standard itself says to center and balance the tile if possible. Results are shown to the nearest 1/16 in, as decimal inches and in millimetres. Limits: the walls are taken as the edge the tile meets, so subtract any perimeter movement gap from the dimension first; the layout is for tiles in a straight grid, and offset (brick) patterns shift alternate rows and need their own layout; out-of-square walls, doorways and the first row seen from the door are not looked at. Tile sizes are the actual measured size; rectified and non-rectified tiles of the same nominal size can differ. The metric toggle shows the room in m; tile and joint can be entered in mm or cm.

ANSI A108.02, American National Standard Specifications for Materials, Environmental and Workmanship Requirements for tile installation, section 4.3: 4.3.1 center and balance areas of tile if possible; 4.3.2 usually no cuts smaller than half size should be made, and make all cuts on the outer edges of the field (as quoted in the CTEF articles below)
CTEF Tile Tip: Centered, Balanced and Small Cuts in Ceramic Tile, Please (Ceramic Tile Education Foundation, in Floor Trends & Installation)
Tile layout: centered, balanced, no small cuts, Ceramic Tile Education Foundation
TCNA Handbook for Ceramic, Glass and Stone Tile Installation, Movement Joint Guidelines (EJ171): perimeter and movement joints are not part of this calculation; read the current edition for yours
A third of a tile as a smaller acceptable cut: an unverified typical installer figure, not taken from a standard

How to plan a centered tile layout

Measure the room both ways. Measure the length and the width between the walls, and the real size of the tile and the grout joint you will use. Subtract any perimeter gap.
Enter the tile size along each direction. Type the tile size in the direction of the length and in the direction of the width, then the joint width.
Compare the two centerings. Read the comparison line for each direction: the centered tile and the centered grout joint each give a cut at the walls, and the calculator says which cut is larger.
Check the flags. A cut under half a tile (or a third, if you chose that) is flagged: switch the centering, or move the layout line off center by a part of a tile.
Snap the lines and dry-lay. Mark the centerlines with a chalk line, dry-lay a row each way with spacers to check the cuts at both walls, then set the tile out from the center.

Worked examples

Project	Result
12 ft room, 12 in tiles, 1/8 in joint, tile centered	11 full tiles across the length, an edge cut of 5 1/4 in at each wall; the cut is under half a tile (6 in), and a centered joint gives 11 5/16 in (11.31 in, 287 mm) cuts instead
The same 12 ft room, grout joint centered on the centerline	10 full tiles across the length, an edge cut of 11 5/16 in at each wall
6 ft room, 12 in tiles, 1/8 in joint, full tile at one wall	5 full tiles across the length, an edge cut of 11 3/8 in at the far wall
16 ft room, 24 in tile length, 1/8 in joint, tile centered, flag below a third of a tile	7 full tiles across the length, an edge cut of 11 1/2 in at each wall; 11 1/2 in (11.5 in, 292 mm) is under half a tile (12 in) but not under a third (8 in)

Frequently asked questions

Should I center a tile or a grout joint on the centerline?: Whichever leaves the larger cuts at the walls. The two options move the whole layout by half a tile, so when one leaves a sliver the other usually does not. For a 12 ft (144 in) room with 12 in tiles and a 1/8 in joint, a centered tile leaves 5 1/4 in cuts and a centered joint leaves 11 5/16 in cuts. The calculator's comparison line shows both for each direction. A common installer tip, repeated by the Ceramic Tile Education Foundation, is to shift from the center of a tile to the center of a joint when the cuts are small.
How small can an edge cut be?: ANSI A108.02 says usually no cuts smaller than half size should be made, and to center and balance the tile if possible. That is the default flag here. It is a guideline about appearance, and "usually" and "if possible" are in the wording: a narrow cut is not a defect in itself. Some installers accept a third of a tile; that figure is a typical one and not from the standard, so check it against your installer or tile maker. Thin cuts are also harder to cut cleanly and more likely to chip.
Why do I enter the layout direction by direction?: The layout across the length and across the width are independent: each has its own tile size (a 12 × 24 tile is 12 in one way and 24 in the other), its own centerline and its own cuts. Enter the length and the width, and the tile size along each. Leave the width empty to look at one direction only.
Where do I snap the centerline?: Half way along each dimension, measured from the same wall on each end to check the room is square, then snap a chalk line. For a centered tile, set a tile so the line runs through its middle. For a centered joint, set the grout joint on the line. Work out from the center; do not start at a wall. Checking the layout against the doorway, so that the cut rows do not show first, can change the answer; the calculator does not look at that.
Do I count the wall gap?: The calculator takes the dimension as the edge the tile meets. Tile installations usually leave a perimeter movement joint (see the TCNA Handbook movement joint guidelines, EJ171, and your tile setting product’s instructions), which the baseboard or sealant then covers. Subtract that gap from each end of the dimension before you type it, or the cuts will come out too wide by the gap.
Is this for brick-offset or herringbone patterns?: No. The calculator lays tiles in a straight grid. An offset pattern shifts every other row, so the ends of the rows have two different cuts, and a diagonal lay is worked at 45 degrees. Use the numbers as a first guide only for those.
How many tiles should I buy?: This calculator only shows the layout. Use the tile calculator for the quantity, with the overage for your pattern, and the grout and thinset calculators for the rest.
What if the tile is bigger than the room dimension?: A centered tile needs the tile to be no longer than the dimension; otherwise the calculator says so, since every tile would be a cut. For a full tile at a wall, zero full tiles and one cut of the whole dimension are shown.

Handy tools

Feet and Inches Calculator: Add up a wall measured in feet, inches and fractions, and get the decimal feet the length and width fields take.
Decimal to Fraction Converter: Turn a decimal cut such as 5.3125 in into the nearest 1/16 on a tape measure.