---
title: "Acrylic (PMMA) — density, melting point and properties"
description: "Acrylic (PMMA) has a density of 1,180 kg/m³. Melting point, strength, conductivity, what it is used for, and whether it floats, rusts or is magnetic."
url: https://atoneplace.net/material/acrylic/
site: "At One Place"
---

# Acrylic (PMMA)

**Density of acrylic (PMMA): 1,180 kg/m³**

1.18 g/cm³ · 73.7 lb/ft³

Clearer than glass — it transmits about 92% of visible light against glass's 90% — and it holds that clarity outdoors for decades, which is why signs are acrylic rather than polycarbonate. It is also brittle: it cracks around drilled holes and chips at edges, so holes are drilled oversize with a bit reground to zero rake. It laser-cuts to a flame-polished edge, which polycarbonate does not, and that alone decides most hobby projects.

## Properties

- **Density:** 1,180 kg/m³ — 1.18 g/cm³
- **Tensile strength:** 50–75 MPa
- **Young's modulus:** 3 GPa
- **Thermal conductivity:** 0.19 W/(m·K)
- **Thermal expansion:** 70 µm/(m·K)
- **Floats in water:** No
- **Magnetic:** No

## What it is used for

- Illuminated signs and display cases
- Aquarium panels
- Light diffusers and lenses
- Laser-cut craft and model parts

## 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
- acrylic (PMMA): 1,180 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× |
| acrylic (PMMA) ← | 1,180 kg/m³ | 1.18× |
| platinum | 21,450 kg/m³ | 21.45× |
| gold | 19,300 kg/m³ | 19.30× |
| tungsten | 19,250 kg/m³ | 19.25× |

## Does it rust?

Acrylic (PMMA) contains no iron, so it cannot rust. Whether it degrades depends on the material, not on oxidation.

## Is it magnetic?

Acrylic (PMMA) is not a metal and has no ferromagnetic response.

## Common questions

### What is the density of acrylic (PMMA)?

1,180 kg/m³, or 1.18 g/cm³.

### Does acrylic (PMMA) float?

No. At 1,180 kg/m³ it is denser than water.

### Is acrylic (PMMA) magnetic?

Acrylic (PMMA) is not a metal and has no ferromagnetic response.

## Related pages

- [Does acrylic (PMMA) float?](https://atoneplace.net/does-it-float/acrylic/)
- [PLA](https://atoneplace.net/material/pla/)
- [ABS](https://atoneplace.net/material/abs/)
- [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/)
- [HDPE](https://atoneplace.net/material/hdpe/)
- [Epoxy resin](https://atoneplace.net/material/epoxy-resin/)

## Sources

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