Ceramic and porcelain tile look alike on the shelf, and both are set with the same ceramic tile spacers and leveling clips. They are not the same material, though, and the differences change how you space and level them, especially as tile gets bigger. This guide explains the difference between ceramic and porcelain tile, why porcelain warpage matters in large sizes, which spacer size fits each, what to do with natural stone, and how to handle warped tile on site.
What is the difference between ceramic and porcelain tile?
Porcelain is a type of ceramic tile made from a denser body and fired so it absorbs very little water: 0.5% or less under ANSI A137.1. Ordinary ceramic tile is more porous, usually softer and easier to cut. Porcelain is harder, heavier and better suited to floors, wet areas and outdoor use.
The ANSI definition of porcelain tile, as summarized by the American National Standards Institute, is ceramic tile with water absorption of 0.5% or less when tested to ASTM C373. Within each group there are subtypes. Glazed ceramic has a decorative glaze over a red or white body, common on walls. Glazed porcelain has a glaze over a porcelain body. Through-body porcelain has the same color all the way through, so chips show less. Some makers call porcelain “porcelain stoneware”. Other ratings you will see on the box include the PEI rating for glaze wear, frost resistance for exterior use, and slip resistance measured as DCOF. Once you know which one you have, our porcelain tile installation guide covers thin-set, cutting and setting porcelain step by step.
| Ceramic tile | Porcelain tile | |
|---|---|---|
| Water absorption | Higher; varies by type | 0.5% or less (ANSI A137.1) |
| Body | More porous, softer | Dense, hard |
| Cutting | Easier; scores and snaps cleanly | Harder; diamond blade recommended |
| Typical use | Walls, backsplashes, light-traffic floors | Floors, showers, high traffic, many exterior uses |
| Typical sizes | Smaller formats more common | Up to large format and slabs |
Why does porcelain warp more in large sizes?
All fired tile shrinks and bows a little in the kiln. Warpage tolerances are written as a percentage of the edge length, so a longer porcelain tile is allowed a larger bow in absolute terms than a short one. That is why large format porcelain shows warpage that a 12×12 tile hides.
ANSI A137.1 warpage limits, as tabulated in LATICRETE TDS 164, show the difference between tile types (edge warpage, whichever value is less):
| Tile type | Allowable edge warpage |
|---|---|
| Pressed floor tile, natural (not sorted) | ±1.0% or 0.12 in |
| Porcelain tile 6 in and larger, calibrated | ±0.5% or 0.08 in |
| Porcelain tile 6 in and larger, rectified | ±0.40% or 0.05 in |
On a long tile, even an in-tolerance bow becomes visible at the joints, which is why large format tile spacers and leveling matter more than spacers alone.
Which spacer size fits ceramic vs. porcelain?
Ceramic wall tile with cushion edges is usually set at 1/16 to 1/8 inch. Porcelain floor tile is commonly set at 1/8 inch, the typical joint for ceramic and porcelain from 12×12 to large format when you want a narrow but visible grout line. Rectified porcelain can go to 1/16 inch where the maker allows.
| Tile | Common joint | Next Level clip |
|---|---|---|
| Glazed ceramic wall tile | 1/16 to 1/8 in | 1/16 or 1/8 in |
| Calibrated porcelain floor tile | 1/8 in or wider | 1/8 in (combine with spacers for wider) |
| Rectified porcelain | 1/16 to 1/8 in | 1/16 or 1/8 in; 1/32 in only where allowed |
Next Level’s clips for ceramic and porcelain tile come in 1/32 inch (1 mm), 1/16 inch (1.5 mm) and 1/8 inch (3 mm). Always check the tile maker’s minimum joint on the box. For help choosing, see the clip size chart and 1/16 vs 1/8 grout line.
Can you use the leveling system on natural stone?
The Next Level system is designed for ceramic and porcelain tile. Stone applications are not specifically recommended, although some installers do use the system with stone. Natural stone such as marble and travertine varies more in thickness and can be sensitive to moisture and pressure.
If you choose to try it on stone, test on a few pieces first, check that the stone thickness falls in the system’s range, and avoid over-tightening on soft or veined stone. Some stone, such as certain green marbles, curls when exposed to moisture from water-based mortars, which LATICRETE TDS 164 notes can cause lippage regardless of the leveling method.
How do you handle warped tile on site?
Handle warped tile by checking a few pieces before you start, sorting them by bow, rotating tiles so edges match, keeping long-tile offsets at 33% or less, using closer clip spacing, and choosing a joint wide enough for the warpage. Return tile that is outside tolerance instead of fighting it.
- Place two tiles face to face, or lay a straightedge along an edge, to see the bow.
- Set crowned and dished tiles so that matching edges meet.
- For tiles with a side over 18 inches in running bond, ANSI A108.02 limits the offset to 33% unless the tile maker specifies otherwise, and adds the edge warpage to the minimum joint.
- Add clips along long edges so the bow is pulled into plane while the mortar cures.
Frequently asked questions
Is porcelain tile harder to keep level than ceramic?
Not by itself, but porcelain is more often large format, and large tile is harder to set flat. Leveling clips help either way.
What lippage is acceptable on ceramic tile?
ANSI A108.02 allows 1/32 inch on most floor tile with joints under 1/4 inch. See what is tile lippage.
Do I need different spacers for porcelain?
No. The same spacers and clips work; choose the width for the joint you need.
Key terms
- Ceramic tile: tile made from fired clay; the broad family that also includes porcelain.
- Porcelain tile: ceramic tile with water absorption of 0.5% or less under ANSI A137.1.
- Porcelain stoneware: a manufacturer’s term for dense porcelain tile.
- Water absorption: the percentage of water a tile body takes in, which separates porcelain from other ceramic tile.
- PEI rating: a scale that rates how well a glazed tile surface resists wear from foot traffic.
- Glazed porcelain: porcelain tile with a glass-like glaze layer on its face.
- Through-body porcelain: porcelain with the same color and pattern through its full thickness.
- Natural stone: quarried material such as marble, travertine, granite or slate cut into tile.
- Marble: a metamorphic natural stone, often veined, that can be soft and moisture sensitive.
- Travertine: a porous natural stone with characteristic holes, usually filled before polishing.
- Warpage tolerance: the maximum bow a tile may have under its product standard.
- Glazed ceramic: non-porcelain ceramic tile with a decorative glaze, common on walls.
- Frost resistance: a tile’s ability to survive freeze-thaw cycles outdoors.
- Slip resistance (DCOF): how slippery a tile is, measured as the dynamic coefficient of friction.
- Porcelain body: the dense, low-absorption clay body under the surface of porcelain tile.
Sources
- ANSI blog, ANSI A137.1-2022: Standard for Ceramic Tile
- LATICRETE TDS 164, Lippage: Causes and Prevention (ANSI A137.1 warpage table)
Setting ceramic or porcelain? The Next Level tile leveling system is designed for both and ships nationwide, sold by quote. Request a quote for clips in your joint size.