---
title: "Magnesium — density, melting point and properties"
description: "Magnesium has a density of 1,738 kg/m³. Melting point, strength, conductivity, what it is used for, and whether it floats, rusts or is magnetic."
url: https://atoneplace.net/material/magnesium/
site: "At One Place"
---

# Magnesium

**Density of magnesium: 1,738 kg/m³**

1.74 g/cm³ · 108.5 lb/ft³

The lightest structural metal in use, at about two thirds the density of aluminum and a fifth that of steel. The catch is fire: magnesium swarf and thin sections burn fiercely and cannot be put out with water, which is why machining shops treat it differently and why it never went into aircraft interiors. It also corrodes readily unless coated, so magnesium castings are always painted or anodized.

## Properties

- **Density:** 1,738 kg/m³ — 1.74 g/cm³
- **Melting point:** 650 °C
- **Tensile strength:** 160–220 MPa
- **Young's modulus:** 45 GPa
- **Thermal conductivity:** 156 W/(m·K)
- **Thermal expansion:** 24.8 µm/(m·K)
- **Floats in water:** No
- **Magnetic:** No

## What it is used for

- Laptop and camera bodies
- Car steering wheel and seat frames
- Sacrificial anodes in water heaters
- Aluminum alloying

## 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
- magnesium: 1,738 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× |
| magnesium ← | 1,738 kg/m³ | 1.74× |
| platinum | 21,450 kg/m³ | 21.45× |
| gold | 19,300 kg/m³ | 19.30× |
| tungsten | 19,250 kg/m³ | 19.25× |

## Does it rust?

Magnesium does not rust — rust is iron oxide specifically — but it does corrode, forming its own oxide or salts over time.

## Is it magnetic?

Magnesium is not ferromagnetic. It is often assumed to be because it is a metal, but most metals are not — only iron, nickel, cobalt and a few alloys are attracted to an ordinary magnet.

## Common questions

### What is the density of magnesium?

1,738 kg/m³, or 1.74 g/cm³.

### Does magnesium float?

No. At 1,738 kg/m³ it is denser than water.

### Is magnesium magnetic?

Magnesium is not ferromagnetic. It is often assumed to be because it is a metal, but most metals are not — only iron, nickel, cobalt and a few alloys are attracted to an ordinary magnet.

## Related pages

- [Does magnesium float?](https://atoneplace.net/does-it-float/magnesium/)
- [Aluminum](https://atoneplace.net/material/aluminum/)
- [Copper](https://atoneplace.net/material/copper/)
- [Gold](https://atoneplace.net/material/gold/)
- [Titanium](https://atoneplace.net/material/titanium/)
- [Iron](https://atoneplace.net/material/iron/)
- [Lead](https://atoneplace.net/material/lead/)
- [Tungsten](https://atoneplace.net/material/tungsten/)
- [Silver](https://atoneplace.net/material/silver/)

## Sources

- Wikidata — Wikimedia Foundation (https://www.wikidata.org/) [CC0 1.0]