---
title: "Gypsum board (drywall) — density, melting point and properties"
description: "Gypsum board (drywall) has a density of 700 kg/m³ (640–800). Melting point, strength, conductivity, what it is used for, and whether it floats, rusts or is magnetic."
url: https://atoneplace.net/material/gypsum-board/
site: "At One Place"
---

# Gypsum board (drywall)

**Density of gypsum board (drywall): 700 kg/m³ (640–800)**

0.70 g/cm³ · 43.7 lb/ft³

A 12.5 mm sheet weighs about 9 kg/m², so a standard 2400 × 1200 board is roughly 25 kg — right at the edge of a one-person lift, which is why 9.5 mm exists. Its fire rating comes entirely from the chemically bound water in the gypsum core boiling off and holding the far face near 100 °C, which is why fire-rated partitions are specified as layers of board rather than as any special material. It has almost no structural strength, so anything heavy hung on it needs a fixing that reaches the stud or a proper cavity anchor.

## Properties

- **Density:** 700 kg/m³ (640–800) — 0.70 g/cm³
- **Tensile strength:** 1–3 MPa
- **Thermal conductivity:** 0.17 W/(m·K)
- **Floats in water:** Yes
- **Magnetic:** No

## What it is used for

- Internal wall and ceiling linings
- Fire-rated partitions and shaft walls
- Suspended ceiling tiles
- Acoustic separating walls

## 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
- gypsum board (drywall): 700 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× |
| gypsum board (drywall) ← | 700 kg/m³ | 0.70× |
| platinum | 21,450 kg/m³ | 21.45× |
| gold | 19,300 kg/m³ | 19.30× |
| tungsten | 19,250 kg/m³ | 19.25× |

## Does it rust?

Gypsum board (drywall) contains no iron, so it cannot rust. Whether it degrades depends on the material, not on oxidation.

## Is it magnetic?

Gypsum board (drywall) is not a metal and has no ferromagnetic response.

## Common questions

### What is the density of gypsum board (drywall)?

700 kg/m³ (640–800), or 0.70 g/cm³.

### Does gypsum board (drywall) float?

Yes. At 700 kg/m³ it is less dense than water's 1,000.

### Is gypsum board (drywall) magnetic?

Gypsum board (drywall) is not a metal and has no ferromagnetic response.

## Related pages

- [Does gypsum board (drywall) float?](https://atoneplace.net/does-it-float/gypsum-board/)
- [Concrete](https://atoneplace.net/material/concrete/)
- [Brick](https://atoneplace.net/material/brick/)
- [Tungsten carbide](https://atoneplace.net/material/tungsten-carbide/)
- [Reinforced concrete](https://atoneplace.net/material/reinforced-concrete/)
- [Graphite](https://atoneplace.net/material/graphite/)
- [Porcelain](https://atoneplace.net/material/porcelain/)
- [Plaster](https://atoneplace.net/material/plaster/)
- [Silicon carbide](https://atoneplace.net/material/silicon-carbide/)

## Sources

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