What is the most common grout line width?

For floor tile, 1/8 in and 3/16 in are the most common joints. Rectified porcelain is often set with 1/16 to 1/8 in joints; handmade or non-rectified tile usually needs 3/16 to 1/4 in or more.

Can I set tile with no grout lines?

No. Industry installation standards call for a grout joint on standard ceramic and porcelain tile, because tiles vary slightly in size and the joint absorbs that variation and small movements. 'Butt-jointed' installation is not recommended for floor tile.

When should I use sanded grout?

Sanded grout is generally used for joints of 1/8 in and wider, because the sand resists shrinking and cracking. Unsanded grout is used for joints narrower than 1/8 in and on surfaces that sand could scratch, such as some polished stone and glass tile. Always follow the grout maker's joint-width range.

Does a wider grout line mean I need fewer tiles?

Yes, slightly, because each tile plus its joint covers more area. The effect is small for big tiles but noticeable for small tiles with wide joints. Enter your joint width in the tile calculator to see the difference.

How deep should grout go?

Grout should fill the joint to nearly the full thickness of the tile. Before grouting, clean out any thinset that squeezed up into the joints so there is room for the grout.

Tile Spacing and Grout Joints: A Practical Guide

The grout joint is the small gap between tiles, and choosing its width is one of the first decisions in any tile project. Too narrow and slightly uneven tiles will look wavy; too wide and the floor looks busy and needs more grout to maintain. This guide explains how to choose a joint width for your tile, which grout to use, and how spacing changes the number of tiles and the amount of grout you buy.

Last updated 2026-11-12

Why tile needs a grout joint at all

No two tiles are exactly the same size. Kiln-fired ceramic and porcelain shrink slightly during firing, and tiles from the same box can differ by a millimeter or more. Many tiles are also slightly warped, so their edges are not perfectly flat. The grout joint absorbs those differences so the lines stay straight. Joints also give the installation a little room for movement as the floor expands and contracts.

That is why tile installation standards, such as those referenced by the Tile Council of North America, call for a minimum joint and recommend making the joint wide enough to hide the actual size variation of the tile you're using. A widely used rule is that the joint should be at least three times the variation in tile size, and never less than 1/16 in.

Recommended joint widths by tile type

Tile type	Typical joint	Why
Rectified porcelain (edges ground square)	1/16–1/8 in	Very consistent sizes allow narrow joints
Standard floor tile, non-rectified	3/16–1/4 in	Hides size variation between tiles
Wall tile and subway tile	1/16–1/8 in	Many wall tiles have spacer lugs built in
Large-format tile (any side 15 in+)	1/8–3/16 in	Slight warpage needs a little room
Wood-look plank tile	1/8–3/16 in	Long planks are prone to slight bowing
Handmade, zellige, terracotta, quarry	1/4–1/2 in	Irregular edges and sizes
Mosaic sheets	Set by the sheet	Match the gap between sheets to the gap within them
Natural stone, calibrated	1/16–1/8 in	Follow the supplier's recommendation

The tile's packaging or technical data sheet often lists a recommended joint. When it does, use it; the manufacturer knows its own size tolerance.

How to check your tile before deciding

Pull 8 to 10 tiles from different boxes.
Measure each one along both edges with a tape measure or caliper and write the sizes down.
Note the largest and smallest measurement. The difference is your size variation.
Multiply that variation by three. If the result is larger than the joint you had in mind, go wider.
Lay the tiles side by side on a flat floor and look along the edges for warpage. Bowed plank tiles in particular may need a wider joint and a shorter offset.

Example: your 12 × 24 in tiles measure between 11.92 in and 11.98 in wide, a variation of 0.06 in. Three times that is 0.18 in, a little over 3/16 in, so a 3/16 in joint is a better choice than 1/16 in for that tile.

Sanded vs unsanded grout

Grout	Typical joint range	Best for
Unsanded (non-sanded)	Under 1/8 in	Narrow wall joints, polished stone and glass that sand could scratch
Sanded	1/8 in and wider	Most floor tile; sand prevents shrinkage cracks in wide joints
Epoxy / high-performance	Per manufacturer	Stain resistance in kitchens and showers; harder to work with

Check the grout bag: manufacturers state the joint widths each product is designed for, and some newer cement grouts cover a wide range in one product.

How joint width affects tile quantity

A tile with a joint occupies its own size plus the joint. The tile calculator includes this: coverage per tile = (length + joint) × (width + joint) ÷ 144. Here is the effect on 100 sq ft, before waste:

Tile	No joint	1/8 in joint	1/4 in joint
4 × 4 in	900	847	798
12 × 12 in	100	98	96
12 × 24 in	50	50	49

With large tiles the joint barely changes the count, so the waste allowance matters far more. With small tiles, a wide joint saves about 10% of the tiles, which is why mosaic estimates should always include the joint.

How much grout you need

Grout fills the joints, so the volume depends on the tile size, joint width and tile thickness. For each square foot of tile, the total length of joint is 144 × (L + W) ÷ (L × W) inches, where L and W are the tile dimensions in inches. Multiply by the joint width and depth (tile thickness) to get the volume.

grout (cu in per sq ft) = 144 × (L + W) ÷ (L × W) × joint width × tile thickness

Worked example

A 60 sq ft bathroom floor with 12 × 12 in tile, 3/8 in thick, and a 3/16 in joint:

Joint length per sq ft: 144 × 24 ÷ 144 = 24 in.
Volume per sq ft: 24 × 0.1875 × 0.375 ≈ 1.69 cu in.
For 60 sq ft: about 101 cu in, or roughly 0.06 cu ft.

Now switch to 2 × 2 in mosaic with a 1/8 in joint and 1/4 in thickness: joint length per sq ft is 144 × 4 ÷ 4 = 144 in, and the volume is 144 × 0.125 × 0.25 = 4.5 cu in per sq ft, more than two and a half times as much grout. Small tiles use far more grout than large ones. Use the volume to compare options, then use the coverage chart on the grout bag, which lists square feet per bag for common tile sizes and joints, to choose how many bags to buy. Add a little extra for waste on the float.

Layout tips that affect spacing

Use spacers or a leveling system. Spacers keep joints even; clip-and-wedge leveling systems also reduce lippage on large tiles.
Limit the offset on long tiles. For plank and rectangular tiles with any side over about 18 in, a common recommendation is an offset of no more than one-third of the tile length, because slight bowing makes a 50% offset show uneven edges.
Dry-lay a row first. Lay tiles with spacers along the longest wall to see where cuts land and to avoid thin slivers at the edges.
Leave movement joints. Perimeter joints at walls and soft (caulked) joints at changes of plane let the floor move without cracking tiles.
Match grout color to the look you want. A close color makes joints disappear and hides minor size variation; a contrasting color highlights the pattern and every irregularity.

Once you've picked a tile and joint, enter both in the tile calculator. If you're laying the tile on a diagonal or herringbone, read how much waste to add for diagonal layouts before you choose the waste percentage.