---
title: "HDPE — density, melting point and properties"
description: "HDPE has a density of 955 kg/m³ (940–970). Melting point, strength, conductivity, what it is used for, and whether it floats, rusts or is magnetic."
url: https://atoneplace.net/material/hdpe/
site: "At One Place"
---

# HDPE

**Density of HDPE: 955 kg/m³ (940–970)**

0.95 g/cm³ · 59.6 lb/ft³

The blue and yellow pipe under every modern street: it is welded rather than jointed, so a run has no leak paths, and it flexes with ground movement instead of cracking like the cast iron it replaced. It also floats, is unaffected by almost every household chemical, and is self-lubricating enough to be used as low-load bearing material. Like polypropylene it will not take glue or paint; the only reliable joining method is heat welding.

## Properties

- **Density:** 955 kg/m³ (940–970) — 0.95 g/cm³
- **Melting range:** 125–135 °C
- **Tensile strength:** 20–37 MPa
- **Young's modulus:** 1 GPa
- **Thermal conductivity:** 0.45 W/(m·K)
- **Thermal expansion:** 120 µm/(m·K)
- **Floats in water:** Yes
- **Magnetic:** No

## What it is used for

- Milk bottles and detergent containers
- Water and gas mains pipe
- Chopping boards and playground furniture
- Chemical storage tanks

## 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
- HDPE: 955 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× |
| HDPE ← | 955 kg/m³ | 0.95× |
| platinum | 21,450 kg/m³ | 21.45× |
| gold | 19,300 kg/m³ | 19.30× |
| tungsten | 19,250 kg/m³ | 19.25× |

## Does it rust?

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

## Is it magnetic?

HDPE is not a metal and has no ferromagnetic response.

## Common questions

### What is the density of HDPE?

955 kg/m³ (940–970), or 0.95 g/cm³.

### Does HDPE float?

Yes. At 955 kg/m³ it is less dense than water's 1,000.

### Is HDPE magnetic?

HDPE is not a metal and has no ferromagnetic response.

## Related pages

- [Does HDPE float?](https://atoneplace.net/does-it-float/hdpe/)
- [PLA](https://atoneplace.net/material/pla/)
- [ABS](https://atoneplace.net/material/abs/)
- [Acrylic (PMMA)](https://atoneplace.net/material/acrylic/)
- [Polycarbonate](https://atoneplace.net/material/polycarbonate/)
- [Polypropylene](https://atoneplace.net/material/polypropylene/)
- [PTFE](https://atoneplace.net/material/ptfe/)
- [Rigid PVC](https://atoneplace.net/material/pvc-rigid/)
- [Epoxy resin](https://atoneplace.net/material/epoxy-resin/)

## Sources

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