The choice between a 1/16 and a 1/8 grout line changes how a floor or wall looks more than almost any other decision after the tile itself. A 1/16 inch joint makes tile read as one surface; a 1/8 inch joint frames each piece. Neither is right for every tile. If you are weighing a 1/16th vs 1/8th grout line, this guide compares the two, covers wood-look and subway tile, explains the thinnest grout line you can realistically use, and shows when to go wider.
1/16 vs 1/8 grout line: what is the difference?
A 1/16 inch grout line is about 1.5 mm wide and makes the joints almost disappear; a 1/8 inch grout line is about 3 mm and stays visible as a thin line. The narrower joint needs more precise tile and a flatter install; the wider one forgives more size variation and lippage.
| Joint | Metric | Look | Typical tile | Lippage visibility |
|---|---|---|---|---|
| 1/32 inch | 1 mm | Nearly seamless | Rectified tile where the tile maker allows it, walls | Very high |
| 1/16 inch | 1.5 mm | Minimal, modern | Rectified porcelain, wall tile | High |
| 1/8 inch | 3 mm | Narrow but visible | Ceramic and porcelain, 12×12 to large format | Moderate |
| 3/16 inch | 4.5 mm | Defined grid | Calibrated (non-rectified) tile, planks in running bond | Lower |
Next Level makes leveling clips that set three of these joints directly: leveling clips in 1/32, 1/16 and 1/8 inch. The full chart of which clip suits which tile is on the clip size chart.
Does a 1/16 grout line look better than 1/8?
A 1/16 grout line looks better when you want the tile, not the grid, to stand out, as with marble-look or concrete-look rectified porcelain. A 1/8 grout line looks better when tiles vary in size or you want a visible pattern. The best-looking joint is the one the tile can actually support.
Tight joints magnify every flaw. With a 1/16 joint, a tile that is slightly larger than its neighbor or slightly warped shows immediately, and a step between edges throws a shadow with no grout line to soften it. With 1/8 inch, small size differences are absorbed in the joint. For Next Level, 1/8 inch is the common joint spacing for ceramic and porcelain tile when you want a narrow but visible grout line, from 12×12 to large format.
1/8 vs 1/16 grout line for wood look tile
For wood-look plank tile, 1/16 inch reads more like real hardwood, but long planks are usually laid in an offset and bow along their length. ANSI A108.02 calls for an average joint of at least 1/8 inch for rectified tiles longer than 18 inches in running bond, so 1/8 inch is the safer default.
The standard is specific here. ANSI A108.02 section 4.3.8.1, as quoted in LATICRETE TDS 164, says that for running bond patterns with tiles that have any side greater than 18 inches, the joint should average at least 1/8 inch for rectified tiles and 3/16 inch for calibrated tiles, increased by the amount of edge warpage. A 1/16 joint on planks can still work in a stacked layout with very flat rectified tile, if the tile maker allows it. See the tile styles most prone to lippage for why planks need extra care.
1/8 vs 1/16 grout line for subway tile
Classic 3×6 subway tile with a cushion edge is usually set at 1/16 to 1/8 inch. Use 1/16 inch for a tight, clean wall with consistent tile; use 1/8 inch for handmade-look or slightly irregular subway tile so the joint can absorb size differences.
Because subway tile is small, lippage is less about the substrate and more about warpage and wall flatness. On a wall in side light, even a 1/16 joint benefits from leveling clips at the long edges.
What is the thinnest grout line possible?
The thinnest grout line in practice is about 1/32 inch (1 mm), used only with precisely rectified tile when the tile maker allows it. Industry guidance treats 1/16 inch as the minimum for most installations, and a joint should be wider than the tile’s actual size variation.
Proposed ANSI language reported in LATICRETE TDS 164 says the actual grout joint should be at least three times the actual range of facial dimensions of the tile supplied, and in no case less than 1/16 inch. A butt joint, where tiles touch with no gap, is not recommended because it leaves no room for size variation or movement. If a 1/32 joint is your goal, measure a few tiles first; our guide to rectified tile explains why only rectified tile is a candidate.
Can you use sanded grout in a 1/16 joint?
Usually not. Sand particles have trouble packing into a 1/16 inch joint, so most grout makers recommend unsanded or fine-aggregate grout for joints under 1/8 inch and sanded grout for 1/8 inch and wider. Always check the joint-width range printed on the grout package.
Epoxy and high-performance grouts often cover a wide joint range, including very narrow joints. Unsanded grout in a wide joint is the opposite problem: it can shrink and crack. Grouting 1/16 grout lines takes patience: work the float diagonally and keep the sponge damp, not wet, so you do not pull grout out of the narrow joint.
1/8 vs 3/16 grout line: when to go wider?
Go to 3/16 inch with calibrated, non-rectified tile, with long tile in running bond, with tile that has noticeable warpage, and with rustic or handmade looks. A wider joint absorbs size variation and makes acceptable lippage less visible.
The ANSI minimum for calibrated tiles longer than 18 inches in running bond is already 3/16 inch on average, so for those tiles a wider joint is not a style choice, it is the baseline. With clips, you can combine a 1/8 inch clip with a standard spacer to build a wider joint. For ceramic versus porcelain specifics, see ceramic and porcelain tile spacers.
Grout line comparison: same tile, three joints
Laid side by side, the same tile at 1/32, 1/16 and 1/8 inch reads as three different floors: almost seamless, minimal, and gridded. Grout color contrast changes the effect as much as width, so a matching grout makes 1/8 inch look closer to 1/16.
Before committing, dry-lay a few tiles with each clip size and look at them from standing height, in the room’s real light. Then match grout color: low contrast quiets the grid, high contrast emphasizes it.
Frequently asked questions
What is the smallest grout line for floor tile?
For most floor tile, 1/16 inch is the practical minimum, and many tile makers specify 1/8 inch or more. Check the box.
Does grout shrink in wide joints?
Some grouts can shrink and crack if used outside their joint range. Pick a grout rated for your joint width.
Is 1/8 inch a good default?
For ceramic and porcelain tile from 12×12 up, yes: it gives a narrow but visible grout line and tolerates normal size variation.
Key terms
- Grout line: the visible strip of grout between two tiles.
- Sanded grout: cement grout with sand aggregate, meant for wider joints, usually 1/8 inch and up.
- Unsanded grout: cement grout without coarse sand, meant for narrow joints under 1/8 inch.
- Grout joint size: the specified width of the joints, set by spacers or leveling clips.
- Hairline grout joint: an extremely narrow joint, around 1/32 inch, possible only with very precise tile.
- 3/16 inch grout line: a joint about 4.5 mm wide, common for calibrated tile and long tile in running bond.
- Grout color contrast: how different the grout color is from the tile, which controls how visible the grid looks.
- Butt joint: tiles set touching with no gap, not recommended because it leaves no room for size variation or movement.
- Grout line width: the finished width of the grout between tile edges.
- Thinnest grout line: the narrowest joint a tile can support, limited by its size variation and the tile maker’s minimum.
- Epoxy grout: a resin-based grout that resists stains and is often rated for a wide range of joint widths.
- Grout shrinkage: the slight volume loss of grout as it cures, which can cause cracks if the grout is used outside its joint range.
Sources
Picked your joint? Next Level clips set 1/32, 1/16 or 1/8 inch joints and keep edges flush, and the Next Level tile leveling system ships nationwide by quote. Request a quote for clips in your joint size.