---
title: "Air — density, melting point and properties"
description: "Air has a density of 1.2 kg/m³ (1–1.29). Melting point, strength, conductivity, what it is used for, and whether it floats, rusts or is magnetic."
url: https://atoneplace.net/material/air/
site: "At One Place"
---

# Air

**Density of air: 1.2 kg/m³ (1–1.29)**

0.00 g/cm³ · 0.1 lb/ft³

About 1.2 kg/m³ at sea level and 20 °C, so the air in a small bedroom weighs roughly 35 kg — more than most people expect, and the reason a vacuum chamber has to be built like a pressure vessel. The range here is temperature and altitude: 1.29 kg/m³ at 0 °C at sea level, 1.13 at 40 °C, and about 1.0 at 2000 m. Still air is a poor conductor at 0.026 W/(m·K), which is why every good insulator — foam, fibreglass, down, wool — works by preventing that air from moving rather than by anything the solid does.

## Properties

- **Density:** 1.2 kg/m³ (1–1.29) — 0.00 g/cm³
- **Thermal conductivity:** 0.026 W/(m·K)
- **Floats in water:** Yes
- **Magnetic:** No

## What it is used for

- The reference for buoyancy and for "how much does a room of air weigh"
- Insulation, when trapped in foam or fibre
- Pneumatic power and tyres
- Combustion oxidant

## How it compares

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

- air: 1.2 kg/m³
- Water — the float line: 1,000 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 |
| --- | --- | --- |
| air ← | 1.2 kg/m³ | 0.00× |
| platinum | 21,450 kg/m³ | 21.45× |
| gold | 19,300 kg/m³ | 19.30× |
| tungsten | 19,250 kg/m³ | 19.25× |

## Does it rust?

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

## Is it magnetic?

Air is not a metal and has no ferromagnetic response.

## Common questions

### What is the density of air?

1.2 kg/m³ (1–1.29), or 0.00 g/cm³.

### Does air float?

Yes. At 1.2 kg/m³ it is less dense than water's 1,000.

### Is air magnetic?

Air is not a metal and has no ferromagnetic response.

## Related pages

- [Does air float?](https://atoneplace.net/does-it-float/air/)
- [Ice](https://atoneplace.net/material/ice/)
- [Paper](https://atoneplace.net/material/paper/)
- [Corrugated cardboard](https://atoneplace.net/material/cardboard/)
- [Cork](https://atoneplace.net/material/cork/)
- [Leather](https://atoneplace.net/material/leather/)

## Sources

- National Oceanic and Atmospheric Administration — NOAA (https://www.noaa.gov/) [Public domain (US Government)]