This is one of the most searched questions in our industry, and the answer is refreshingly simple. Perspex and acrylic are the same material. Perspex is a brand name for acrylic sheet, in exactly the same way that Hoover is a brand name for vacuum cleaner. The material itself is polymethyl methacrylate, or PMMA, regardless of what name is printed on the protective film.
So why does the confusion exist, and does it ever actually matter which one you buy?
Where the Names Come From
Acrylic was developed in the early 1930s by chemists working independently in Britain and Germany. In the UK, Imperial Chemical Industries trademarked their version as Perspex in 1934. The name comes from the Latin for ‘to see through’, which makes sense for a material prized for its clarity. In Germany, Rohm and Haas developed their version as Plexiglas. In the US, you’ll hear Plexiglass used the way we use Perspex over here.
Over the decades, Perspex became so widely used in the UK that it effectively became a generic term. People ask for Perspex when they mean any clear acrylic sheet, just as they might ask someone to Hoover the floor regardless of the vacuum brand. The trademark is still active and owned by Perspex International, but in everyday conversation, Perspex and acrylic are used interchangeably.
When the Brand Actually Matters
For most projects, it doesn’t matter at all. A clear acrylic sheet from any reputable manufacturer will give you the same core properties: 92% light transmission, UV stability, impact resistance roughly 17 times greater than glass and a working temperature range that handles British weather without issue.
Where Perspex-branded sheet can make a difference is in the manufacturer’s guarantee. Genuine Perspex carries a 10-year warranty against yellowing and UV degradation. Some generic acrylic brands offer similar guarantees, but not all do. If your project is outdoors and needs to look pristine for years, that guarantee gives peace of mind. For indoor applications, secondary glazing, craft projects or anything where long-term UV exposure isn’t a factor, the brand on the label is largely irrelevant.
The Question That Actually Matters
Rather than worrying about Perspex vs acrylic, the distinction worth understanding is cast vs extruded. These are the two manufacturing methods for acrylic sheet, and they genuinely affect how the material performs. Cast acrylic is denser, harder and machines more cleanly. Extruded acrylic is more affordable and has more consistent thickness. We’ve covered this in detail in our cast vs extruded acrylic guide if you want the full breakdown.
In short: Perspex vs acrylic is a naming question with no practical impact. Cast vs extruded is a material question that affects your project. Focus on the second one.
What About Plexiglass?
Same material again, just the name used predominantly in the US and parts of Europe. Plexiglas (one ‘s’) is the registered trademark of Rohm GmbH in Germany. Plexiglass (two ‘s’s) has become the genericised version, much like Perspex in the UK. If you’re searching for suppliers or comparing products online, all three terms will lead you to the same thing.