---
title: "Which drill bit should I use for porcelain tile?"
description: "A diamond core bit, cooled with water, at low speed — carbide spear points do not cut porcelain. The ranked options, the technique that changes the outcome, and what"
url: https://atoneplace.net/which/drill-bit-porcelain-tile/
site: "At One Place"
---

# Which drill bit should I use for porcelain tile?

**Which drill bit should I use for porcelain tile?: A diamond core bit, cooled with water, at low speed — carbide spear points do not cut porcelain.**

Porcelain is fired to near-vitrification, so it is denser and much harder than ordinary ceramic wall tile — hard enough that tungsten carbide barely scratches it and only diamond abrades it at a useful rate. That difference is why so many people arrive at this question having already destroyed two tile bits. Diamond cutting is a grinding process, and grinding generates heat that both cracks the tile and burns the bond holding the diamonds on, so water is doing two jobs: cooling and flushing away the swarf that would otherwise glaze the rim. Starting is the other difficulty, since a core has no point: tilt the bit to cut a crescent first, then bring it upright once it has a groove to run in.

## The options, ranked

*Ranked best-first for the stated job. The third column is why the others exist.*

| Option | Good at | Bad at |
| --- | --- | --- |
| Diamond core bit | The only reliable option: a sintered or vacuum-brazed diamond rim grinds through vitrified porcelain and natural stone. | Needs constant cooling and low speed, and is ruined by running dry. |
| Wet diamond core with a guide jig | The suction or spring jig holds the core on the mark and holds a small reservoir of water — the professional setup. | Another thing to buy for a job that may be one hole. |
| Carbide spear point | Fine on ordinary glazed ceramic. | Blunts within seconds on porcelain and polishes the surface without cutting. |

## Technique that changes the outcome

1. Low speed, no hammer, and never let the rim run dry
2. Start at an angle to cut a groove, then bring the core upright
3. Build a plasticine dam around the mark and fill it with water, or use a jig with a reservoir
4. Lift every few seconds to let water back into the cut
5. Ease off at breakthrough so the core does not snatch and chip the back of the tile

## What goes wrong

- Dry-drilling porcelain, which kills the bit and produces respirable silica dust
- Any hammer action
- Pressing harder when it slows — that is heat, not lack of force

> Compiled practical guidance rather than a published standard. Product formulations vary by brand and market, so read the label — and where the work is structural, electrical or gas, the regulations that apply where you are govern rather than anything here.

## Other drill bit questions

| For | Use |
| --- | --- |
| Tile | A spear-point carbide or diamond bit in rotary mode only — hammer action shatters tile, every time. |
| Metal | An HSS twist drill, ideally with a 135° split point, run slowly with firm pressure and cutting fluid. |
| Concrete | An SDS-plus carbide bit in a rotary hammer — a normal hammer drill will get there eventually and blunt several bits doing it. |
| Masonry | A carbide-tipped masonry bit in hammer mode for brick and block; step up to an SDS rotary hammer above about 10 mm. |
| Stainless steel | A cobalt bit at low speed with heavy constant pressure and cutting fluid — and never let it stop cutting. |
| Wood | A brad point bit for clean holes up to about 13 mm; an auger for depth and a Forstner for a flat bottom. |
| Plasterboard (drywall) | Almost none — an ordinary HSS or brad point bit in rotary mode, and the real question is which fixing goes in the hole. |
| Glass | A spear-point carbide or a diamond bit, run slowly under water — and toughened glass cannot be drilled at all. |
| Plastic | An HSS bit ground to a shallower rake, or a plastic-specific bit, at low speed with a backing board — acrylic especially will crack. |
| Hardened steel | Solid carbide in a rigid setup, or soften the spot first — HSS and cobalt cannot cut anything much above 50 HRC. |
| Aluminium | A sharp HSS bit at high speed with a wax or paraffin lubricant — the problem is aluminium sticking to the bit, not hardness. |
| Large holes in wood | Spade for speed and roughness, auger for depth, Forstner for a clean flat bottom, hole saw for big diameters in thin stock. |

## Common questions

### Which drill bit should I use for porcelain tile?

A diamond core bit, cooled with water, at low speed — carbide spear points do not cut porcelain.

### What should I avoid?

Dry-drilling porcelain, which kills the bit and produces respirable silica dust Any hammer action Pressing harder when it slows — that is heat, not lack of force

## Related pages

- [Which drill bit should I use for tile?](https://atoneplace.net/which/drill-bit-tile/)
- [Which drill bit should I use for metal?](https://atoneplace.net/which/drill-bit-metal/)
- [Which drill bit should I use for concrete?](https://atoneplace.net/which/drill-bit-concrete/)
- [Which drill bit should I use for masonry?](https://atoneplace.net/which/drill-bit-masonry/)
- [Which drill bit should I use for stainless steel?](https://atoneplace.net/which/drill-bit-stainless-steel/)
- [Which drill bit should I use for wood?](https://atoneplace.net/which/drill-bit-wood/)
- [Which drill bit should I use for plasterboard?](https://atoneplace.net/which/drill-bit-plasterboard/)
- [Which drill bit should I use for glass?](https://atoneplace.net/which/drill-bit-glass/)
- [Which drill bit should I use for plastic?](https://atoneplace.net/which/drill-bit-plastic/)
- [Which drill bit will go through hardened steel?](https://atoneplace.net/which/drill-bit-hardened-steel/)

## Sources

- Typical range compiled from manufacturer specifications — At One Place (/about/)