---
title: "Water — density, melting point and properties"
description: "Water has a density of 1,000 kg/m³ (958–1,000). Melting point, strength, conductivity, what it is used for, and whether it floats, rusts or is magnetic."
url: https://atoneplace.net/material/water/
site: "At One Place"
---

# Water

**Density of water: 1,000 kg/m³ (958–1,000)**

1.00 g/cm³ · 62.4 lb/ft³

Exactly 1000 kg/m³ at 4 °C by historical definition, which is why one litre weighs one kilogram and why every density on this page can be read as "times heavier than water". It is densest at 4 °C rather than at freezing — the anomaly that makes ice float, lets lakes freeze from the top down, and is the reason aquatic life survives winter. Seawater is about 1025 kg/m³, which is why you float more easily in the sea, and the 958 kg/m³ low here is water at boiling point.

## Properties

- **Density:** 1,000 kg/m³ (958–1,000) — 1.00 g/cm³
- **Melting point:** 0 °C
- **Thermal conductivity:** 0.6 W/(m·K)
- **Floats in water:** No
- **Magnetic:** No

## What it is used for

- The reference for specific gravity and for "does it float"
- Coolant and heat transfer fluid
- Concrete mixing and curing
- Hydraulic testing and ballast

## 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
- 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× |
| water ← | 1,000 kg/m³ | 1.00× |
| platinum | 21,450 kg/m³ | 21.45× |
| gold | 19,300 kg/m³ | 19.30× |
| tungsten | 19,250 kg/m³ | 19.25× |

## Does it rust?

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

## Is it magnetic?

Water is not a metal and has no ferromagnetic response.

## Common questions

### What is the density of water?

1,000 kg/m³ (958–1,000), or 1.00 g/cm³.

### Does water float?

No. At 1,000 kg/m³ it is denser than water.

### Is water magnetic?

Water is not a metal and has no ferromagnetic response.

## Related pages

- [Does water float?](https://atoneplace.net/does-it-float/water/)

## Sources

- United States Geological Survey — USGS (https://www.usgs.gov/) [Public domain (US Government)]