---
title: "Tempered glass — density, melting point and properties"
description: "Tempered glass has a density of 2,500 kg/m³. Melting point, strength, conductivity, what it is used for, and whether it floats, rusts or is magnetic."
url: https://atoneplace.net/material/tempered-glass/
site: "At One Place"
---

# Tempered glass

**Density of tempered glass: 2,500 kg/m³**

2.50 g/cm³ · 156.1 lb/ft³

Chemically the same soda-lime glass, heated to near softening and then chilled fast so the surface is locked in compression — a crack cannot start until that compression has been overcome, which is why it is four to five times stronger. It cannot be cut or drilled afterwards; any breach of the surface releases the stored energy and the whole pane dices into blunt fragments, which is the point for car and shower glass. It also fails spontaneously years later from nickel sulfide inclusions, which is a known and unavoidable low-rate defect rather than a fault.

## Properties

- **Density:** 2,500 kg/m³ — 2.50 g/cm³
- **Tensile strength:** 120–200 MPa
- **Young's modulus:** 70 GPa
- **Thermal conductivity:** 1 W/(m·K)
- **Hardness:** 5.5 Mohs
- **Thermal expansion:** 9 µm/(m·K)
- **Floats in water:** No
- **Magnetic:** No

## What it is used for

- Car side and rear windows
- Shower screens and glass doors
- Phone screen protectors
- Balustrades and shelving

## How it compares

*Water is 1,000 kg/m³. Anything with a shorter bar than water floats in it.*

- air: 1.2 kg/m³
- expanded polystyrene foam: 20 kg/m³
- rigid polyurethane foam: 40 kg/m³
- Water — the float line: 1,000 kg/m³
- tempered glass: 2,500 kg/m³
- tungsten: 19,250 kg/m³
- gold: 19,300 kg/m³
- platinum: 21,450 kg/m³

*Water is 1,000 kg/m³. Anything below that floats.*

| Material | Density | Relative to water |
| --- | --- | --- |
| rigid polyurethane foam | 40 kg/m³ | 0.04× |
| expanded polystyrene foam | 20 kg/m³ | 0.02× |
| air | 1.2 kg/m³ | 0.00× |
| tempered glass ← | 2,500 kg/m³ | 2.50× |
| platinum | 21,450 kg/m³ | 21.45× |
| gold | 19,300 kg/m³ | 19.30× |
| tungsten | 19,250 kg/m³ | 19.25× |

## Does it rust?

Tempered glass contains no iron, so it cannot rust. Whether it degrades depends on the material, not on oxidation.

## Is it magnetic?

Tempered glass is not a metal and has no ferromagnetic response.

## Common questions

### What is the density of tempered glass?

2,500 kg/m³, or 2.50 g/cm³.

### Does tempered glass float?

No. At 2,500 kg/m³ it is denser than water.

### Is tempered glass magnetic?

Tempered glass is not a metal and has no ferromagnetic response.

## Related pages

- [Does tempered glass float?](https://atoneplace.net/does-it-float/tempered-glass/)
- [Soda-lime glass](https://atoneplace.net/material/soda-lime-glass/)
- [Borosilicate glass](https://atoneplace.net/material/borosilicate-glass/)
- [Fused quartz](https://atoneplace.net/material/fused-quartz/)

## Sources

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