Short answer: Acrylic weighs about half as much as glass, resists impact several times better (Plaskolite rates standard acrylic at 2 to 10 times double-strength glass), transmits 92% of light at any thickness, and breaks into large pieces rather than sharp shards. Glass is much harder to scratch, stiffer, doesn't burn, and handles heat far better: acrylic is rated for only about 160 to 180 °F (71 to 82 °C) continuous. Choose acrylic for frames, displays, signs, and anything that could break or be shipped; choose glass for hot, abrasive, or non-combustible uses.
Acrylic vs glass at a glance
| Acrylic | Glass (ordinary float glass) | |
|---|---|---|
| Weight | About half: 1/4 in. ≈ 1.46 lb/ft² | 1/4 in. ≈ 3.2 lb/ft² |
| Impact resistance | 2 to 10 times double-strength glass (Plaskolite); 2.4 J vs 0.7 J in an instrumented test at 1/8 in. | Breaks easily; tempered glass is about 4 to 5 times stronger than annealed |
| How it breaks | Large pieces, not slivers | Annealed: sharp shards. Tempered: small pieces |
| Light transmission | 92% at any thickness, no tint | About 90% at 1/8 in., 83% at 3/4 in.; green edge (low-iron glass about 90 to 91%) |
| Scratch resistance | Scratches fairly easily | Very scratch resistant |
| Heat | Continuous service 160 to 180 °F (71 to 82 °C); softens about 195 to 240 °F | Handles hot dishes and much higher temperatures |
| Stiffness | Flexes more | Very stiff |
| Thermal expansion | About 8 times glass; a 48 in. panel moves about 3/16 in. over 100 °F | Very low |
| Insulation | U-factor about 10% lower than glass the same thickness | Conducts heat more |
| Cutting and shaping | Laser cut into any shape, drilled, bent, polished | Straight cuts and simple shapes; holes and curves are specialist work; tempered can't be cut after tempering |
| Cleaning | Mild soap and water; no Windex-type sprays or full-strength alcohol | Any glass cleaner |
| Fire | Combustible | Doesn't burn |
Is acrylic stronger than glass?
Against impact, yes. Manufacturers put the gap at several times, not the 17 or 30 times you'll see on some websites: Plaskolite rates standard Optix acrylic at 2 to 10 times stronger than double-strength glass, and in its instrumented impact test on 1/8 in. samples, acrylic absorbed 2.4 J vs 0.7 J for glass. Impact-modified acrylics such as Duraplex reach 10 to 30 times. When acrylic does break, Acrylite notes it breaks into comparatively large pieces instead of sharp slivers, and its sheet meets ANSI Z97.1 for safety glazing from 0.080 to 0.500 in. That makes it the safer choice for kids' rooms, gyms, boats, RVs, picture frames that get shipped, and anything mounted overhead.
Glass is stiffer, so a large glass panel flexes less, and glass doesn't creep under long-term load the way plastics do. Tempered glass is also four to five times stronger than annealed glass. Where impact is the real risk and acrylic isn't enough, polycarbonate is far tougher still; see acrylic vs polycarbonate.
Is acrylic clearer than glass?
Slightly, and more so in thick panels. Clear acrylic transmits 92% of visible light and has no color, because it absorbs less than 0.5% per inch. Ordinary glass has a green tint from iron: Vitro gives clear glass about 90% at 1/8 in. but about 83% at 3/4 in. Low-iron glass (such as Starphire) stays around 90 to 91%. In thin sheet, most people can't tell the difference from the front. For thick panels, such as aquariums, acrylic stays clear where glass looks green.
Does acrylic scratch more than glass?
Yes. This is acrylic's biggest weakness. Wiping it with a dry paper towel or a gritty cloth leaves fine scratches, and keys or sand scratch it easily. Glass resists all of that. On the plus side, light scratches in acrylic can be polished out, which you can't do with glass. Abrasion-resistant coated acrylic is available for high-wear uses. Read does acrylic scratch easily and how to remove scratches from acrylic.
How do acrylic and glass handle heat?
Glass handles heat far better. Acrylite rates its cast acrylic for 180 °F (82 °C) continuous service and its extruded sheet for 160 °F (71 °C); extruded starts to soften above about 195 °F. That rules acrylic out for fireplace doors, oven windows, near stovetops, and close to hot light bulbs. It also burns, while glass doesn't. More in acrylic heat resistance and melting point.
Acrylic also expands with temperature about eight times as much as glass: Acrylite says a 48 in. panel moves about 0.002 in. per °F, or about 3/16 in. over a 100 °F swing. Frames and mounting holes need clearance for that. On the plus side, acrylic resists thermal shock better than glass and insulates about 10% better.
Which costs more?
It depends on the job. Plain window glass is often cheaper per square foot for simple rectangles. Once you need shapes, holes, polished edges, tempering, or safe shipping, acrylic is often the more affordable option, because cutting it into any shape is quick and it doesn't break in transit. See your price instantly in the instant quote.
When is glass still better?
- Anywhere hot: fireplace screens, oven doors, backsplashes behind stoves.
- Surfaces that get scrubbed with abrasive cleaners or slide dishes around constantly.
- Where a non-combustible material is required (check your local code).
- Large mirrors where perfect flatness matters.
- Exterior doors and storefronts where safety glazing rules apply (ask your inspector).
When is acrylic better?
- Picture frames, especially large ones or ones you'll ship. See acrylic vs glass for picture frames.
- Display cases, cabinet inserts, and shelves you want cut to a custom shape.
- Windows in sheds, coops, boats, and RVs.
- Signs, sneeze guards, dividers, and anything laser cut, engraved, or bent.
- Table covers, with care about hot dishes. See acrylic vs tempered glass for tabletops.
Questions
How can I tell acrylic from glass?
Acrylic feels warmer to the touch, weighs about half as much, and sounds dull rather than ringing when tapped. Glass edges usually look green; clear acrylic edges don't.
Can I replace a glass window with acrylic?
Often, yes, for sheds, garages, barns, and storm windows. Use the same thickness or one size up, leave expansion room in the frame (Plaskolite suggests about 1/16 in. per foot), and check your local code for windows where safety glazing rules apply.
Is acrylic really 17 times stronger than glass?
That figure comes from retailer marketing, not manufacturer data. Plaskolite rates standard acrylic at 2 to 10 times double-strength glass for impact, and impact-modified acrylic at 10 to 30 times. Acrylic is far safer when it breaks either way.
How much lighter is acrylic than glass?
About half. Plaskolite lists 1/8 in. (3.18 mm) sheet at 3.66 kg/m² for acrylic and 7.81 kg/m² for glass; in US units that's about 0.75 vs 1.6 lb/ft².
Sources
- Acrylite: Cell cast sheet (GP) physical properties
- Plaskolite: Fabrication guide (impact vs double-strength glass)
- Plaskolite: TUFFAK GP data sheet (impact, weight, expansion of polycarbonate, acrylic, and glass)
- Vitro Glass Education Center: Daylighting with low-iron glasses
- Vitro Glass Education Center: Heat-strengthened vs tempered glass