Does Acrylic Block UV Light?

Short answer: Standard clear acrylic blocks UVC and UVB but only part of UVA: Acrylite's data shows very little transmission below about 345 nm, a thickness-dependent amount from 345 to 395 nm, and 92% from 395 nm up. UV-filtering grades such as Acrylite Gallery UV filtering (OP3) and Plexiglas UV100 block about 99.7% of UV, up to 390 nm or 380 nm respectively. UV-transmitting grades made for tanning beds pass about 80% at 300 nm. None block blue light unless tinted.

Key facts

Acrylic type	Example products	UV behavior (maker data)
Standard clear	Acrylite extruded, Plexiglas GS and XT 0A000	Very little transmission below about 345 nm; 345 to 395 nm varies with thickness; 92% from 395 nm into the visible. Röhm calls standard grades "largely UV-absorbing".
UV-filtering	Acrylite Gallery UV filtering (OP3), Plexiglas XT UV100, Perspex VE and VA, Plexiglas UF-3 and UF-5 (Altuglas)	OP3 absorbs about 99.7% from 200 to 390 nm. UV100 blocks at least 99.7% from 280 to 380 nm at 3 mm. Perspex VE absorbs 99.99% below 400 nm.
UV-transmitting	Plexiglas GS Clear 2458, Plexiglas XT 0A770 and 0A370, Acrylite OP-4	OP-4 transmits about 80% at 300 nm rising to about 92% at 400 nm, with transmission starting near 250 nm.

Visible light: clear acrylic of every type above transmits about 92%.
Ordinary picture-framing float glass gives under 40% UV protection, according to Röhm.
UPF: Röhm reports Plexiglas roofing sheet tested at UPF 50+ (at least 98% of UV blocked) under AS/NZS 4399.

The three kinds of UV, briefly

UVC (100 to 280 nm): germicidal lamps. The atmosphere filters out all of the sun's UVC.
UVB (280 to 315 nm): the main cause of sunburn. Most is filtered by the atmosphere, so only a small share reaches the ground.
UVA (315 to 400 nm): about 95% of the UV that reaches the ground, per the World Health Organization. It drives much of the fading in art, fabric, and dyes.

Visible light starts at about 400 nm (violet). Blue light is roughly 400 to 500 nm.

How much UV does regular clear acrylic block?

Standard clear acrylic blocks essentially all UVC and UVB and the shorter part of UVA. Acrylite's light-transmission data for colorless extruded sheet shows very small transmission below about 345 nm. From 345 to 395 nm, how much passes depends on thickness, and from 395 nm up, every thickness transmits 92%. So a good share of the longer-wave UVA, the part closest to visible light, gets through.

Formulas differ between makers. Altuglas notes that even among its own Plexiglas grades, MC (extruded) passes slightly more long-wave UV than G (cast), and that the curves for standard sheet change with thickness. In practical terms: you won't get a sunburn through a standard acrylic window, but a poster or fabric behind it will still fade over time.

What does UV-filtering acrylic block?

UV-filtering acrylic has UV absorbers built into the plastic, not coated on, so the protection doesn't wear off. Published numbers for common grades:

Acrylite Gallery UV filtering (OP3): absorbs about 99.7% of UV from 200 to 390 nm. Older Cyro/Evonik literature quoted about 98%, which is why you'll still see that figure online.
Plexiglas XT 0A570 (UV100): at least 99.7% UV protection from 280 to 380 nm at 3 mm (1/8 in.) thick, with 92% visible light transmission.
Perspex VE: absorbs 99.99% of UV below 400 nm, made for museum glazing.
Plexiglas UF-3 and UF-5 (Altuglas): absorb all UV at 390 nm and below plus some violet light from 400 to 450 nm, which gives UF-3 a very faint yellow edge tint. UF-4 lets slightly more UV through but has no tint.

Use it for framing art, photos, documents, and textiles, for display cases holding signed jerseys or anything with fading inks, and for covers over sun-sensitive goods in shop windows.

Visible light also fades things, more slowly. Altuglas points out that UV-filtering grades don't block the 400 to 500 nm violet-blue band, so they slow fading rather than stop it. We stock UV-filtering clear in 1/8 and 1/4 in.; more in UV-filtering acrylic and acrylic vs glass for picture frames.

Is there acrylic that lets UV through?

Yes. UV-transmitting grades leave out the UV absorbers and are made to resist degradation under strong UV:

Tanning beds: Plexiglas GS Clear 2458 (cast, 3 to 8 mm), Plexiglas XT 0A770 (extruded, up to 3 mm, for lamp canopies), and Acrylite OP-4. Cyro's OP-4 data shows about 80% transmission at 300 nm and nearly unchanged transmission after 10,000 hours under a tanning lamp.
Conservatories and sun rooms: Röhm lists Plexiglas XT 0A370 as a UV-transmitting, UV-resistant sheet for conservatories and sun terraces.
UV curing of resins, inks, and adhesives through a window, and some research greenhouses.
Reptile enclosures where UVB lighting must pass through a panel. Most keepers mount UVB lamps inside the enclosure instead, because standard acrylic absorbs most UVB. See is acrylic safe for fish and reptiles.

UV-transmitting sheet is a special-order product, so ask before you design around one.

Does acrylic block blue light?

No. Blue light is visible light, and clear acrylic transmits it along with the rest of the visible spectrum. "Blue light blocking" screens and glasses use yellow or amber tints or special coatings. A yellow, amber, or orange tinted acrylic will filter blue light, and how much depends on the color. Gray and bronze tints reduce all colors more evenly.

Does UV exposure damage acrylic itself?

Very little in sunlight. Acrylic is one of the most UV-stable clear plastics, and Röhm and 3A Composites warrant clear sheet against yellowing for 30 years. See does acrylic turn yellow and can acrylic be used outdoors. The exceptions are artificial sources: Altuglas says intense UV between 280 and 320 nm (sunlamps, mercury vapor lamps) can cause slight yellowing, and germicidal UV-C around 260 nm degrades all acrylic, so shield parts from direct UV-C lamps.

Does thickness change UV blocking?

For standard acrylic, yes, in the 345 to 395 nm band: thicker sheet absorbs more of that long-wave UVA. For UV-filtering grades, Altuglas reports the same curve at every thickness, and Röhm rates UV100 at 3 mm, so 1/8 in. sheet is enough for framing.

Need UV-filtering frame glazing or a display cover cut to size? Enter your dimensions in the instant quote and choose UV-filtering clear, or see acrylic picture frames and acrylic display cases.

Questions

Can you get sunburned through acrylic?

Sunburn is mostly caused by UVB, which standard clear acrylic blocks, so burning through it is very unlikely. Some long-wave UVA still gets through regular acrylic, so long exposure can still contribute to skin aging.

How can I tell if acrylic is UV-filtering?

You usually can't by eye. A UV flashlight (around 365 to 395 nm) helps: shine it through the sheet onto a fluorescent item like a highlighter mark or white paper. If the glow mostly disappears behind the sheet, it's blocking UV. A 395 nm light is a tougher test, since standard sheet starts transmitting fully around there.

Can UVC disinfection light pass through acrylic?

Not through standard acrylic, which absorbs UVC. Even UV-transmitting tanning grades pass only a small part of UVC. UVC disinfection works only on directly exposed surfaces, and long exposure degrades the acrylic itself.

Does acrylic block more UV than glass?

Standard acrylic and ordinary window glass both stop UVB and pass part of the UVA. Röhm puts conventional picture glass at under 40% UV protection. UV-filtering acrylic, at about 99.7%, blocks far more than plain glass, which is why it's used for conservation framing.

Do plants grow under acrylic if it blocks some UV?

Yes. Acrylite says plants grow as well under its colorless sheet as under glass, because photosynthesis uses visible light, which acrylic passes at 92%. See acrylic greenhouse panels.

Does acrylic block UV light?