PLA or ASA: the short answer
Choose PLA for prints that stay indoors, don't get hot, and need to look good or be dimensionally accurate. Choose ASA if your print will be in the sun, get warmer than 55 °C, or needs to withstand impact.
PLA is easier to print and provides sharper details. ASA lasts for years in places where PLA would give up within a few months.
The difference between PLA and ASA at a glance
What is PLA and what is it good for?
PLA (polylactic acid) is the most commonly used filament in 3D printing. Manufacturers make it from plant-based raw materials like corn starch or sugarcane. It prints at a low temperature and barely shrinks while cooling, making it very accurate to print with.
That’s also where its strength lies: sharp edges, fine details, and a smooth surface. For decorations, scale models, indoor holders, prototypes to test a shape, and gifts, PLA is often the best choice. It is rigid and feels solid.
Its weak spot is heat. PLA starts to soften around 55 to 60 °C. That sounds high, but a dashboard or a south-facing windowsill can easily reach that temperature in the summer.
What is ASA and why does it hold up outdoors?
ASA stands for acrylonitrile styrene acrylate. You can think of it as the outdoor version of ABS. It has the same tough base, but with an acrylate rubber that protects the material against UV light. That’s why the automotive industry has used ASA for years for mirror caps, grilles, and other parts that sit in the sun day in and day out. In the material specifications from Stratasys you can see how industrial printers use ASA for end-use products.
ASA remains dimensionally stable up to about 95 °C, barely fades in the sun, and flexes a little before breaking. The downside is in the printing process itself. ASA requires a high print temperature, an enclosed printer, and good ventilation. Without those three, the print will warp or the layers will delaminate.
PLA vs ASA compared by property
UV light and weather resistance
This is the biggest difference. PLA fades in direct sunlight and becomes brittle over time. Moisture and fluctuating temperatures only speed this up. ASA, on the other hand, is made for the outdoors: the color stays true and the material remains tough, even after years of exposure to the elements. Want to know which other materials hold up outside? Then read the 3 best 3D printing materials for outdoor use.
Heat resistance
PLA loses its shape around 55 to 60 °C, while ASA doesn't start to soften until about 95 °C. Take a phone mount in your car as an example. A PLA version will sag after a sunny afternoon, whereas an ASA version won't be affected at all. Looking for something that can handle even more heat? In the most heat-resistant filament you can see which options outperform ASA.
Strength and impact resistance
Here’s a surprise. On paper, PLA is stronger: if you pull on a PLA rod, it holds up to more force than ASA. But PLA is rigid and brittle. If a PLA print hits the ground or takes a hit, it often snaps instantly.
ASA is tougher. It has a bit of give and absorbs impacts much better. For parts that move, clamp, or take the occasional knock, ASA is usually the stronger choice in practice. By the way, strength also depends on the infill and the number of walls.
Chemical resistance
Will your print come into contact with oil, grease, or cleaning agents? Then ASA wins. It handles oils, greases, and diluted acids and bases well. One exception: acetone dissolves ASA. That’s exactly why you can use acetone vapor to smooth out ASA prints.
PLA is less robust. It can handle water and mild soap, but strong cleaning agents and hot water will eventually damage the surface. So, for a container in the workshop or a part near an engine, PLA isn't a great idea.
Printability and dimensional accuracy
PLA is the easiest filament there is. It prints at 190 to 230 °C, adheres well to the print bed, and barely shrinks. ASA prints at 240 to 260 °C with a bed temperature around 100 °C. It shrinks more while cooling, which means warping is a real risk: the corners can lift off the bed and warp. For that reason, an enclosed printer isn't a luxury for ASA—it's a requirement.
Are you having your part printed instead of doing it yourself? Then you don't need to worry about this. Just keep in mind that because of that shrinkage, ASA is slightly less dimensionally accurate than PLA for very precise fits.
Post-processing
Both materials can be sanded, glued, and painted. PLA is trickier to sand because it heats up and smears if there's too much friction. ASA is easier to sand and can be smoothed to a glossy finish with acetone vapor. Want to paint your print yourself? In Painting 3D prints you can read which paint and primer to use for each material.
Price per kilo and the real cost of a print
How much of a difference does it make to your wallet? Less than you think. At a Dutch webshop, a kilo of PLA from a well-known brand costs around €23 to €27, and ASA costs between €30 and €40, though it varies quite a bit by brand.
If you calculate that for a 50-gram print, the filament difference is at most a euro. The real price difference is in the printing itself. ASA prints more slowly, requires more monitoring, and is more prone to failure with large or flat shapes. So, an ASA print ends up being slightly more expensive, but usually not by much. In the price calculator you can see the difference for your model side-by-side.
Sustainability and the environment
PLA is made from plant-based raw materials, while ASA is petroleum-based. On that point, PLA scores better. However, the picture is more nuanced. PLA only breaks down in an industrial composting facility, not in your garden or in nature. And you don't have to reprint an ASA part three times if it lasts ten years outdoors. For outdoor use, the most sustainable material is often the one that lasts the longest.
Which filament should you choose for your project?
Still unsure? These rules of thumb will help you choose:
- Decoration, models, or indoor gifts: PLA. You get the best detail for the lowest price.
- Prototypes to test shape and size: PLA. Fast, cheap, and accurate.
- Anything that will be in the sun or outdoors: ASA. Think of garden parts, house numbers, covers, and wall-mounted brackets.
- Parts in or on a car: ASA. A car in the summer sun gets too hot for PLA.
- Parts that need to absorb impact or come into contact with oil and grease: ASA.
- A replacement part for an appliance: that depends on the location. If it gets hot or is under stress, choose ASA.
And what if PLA is too weak but ASA is overkill?
There is a middle ground between the two: PETG. It is tougher and more heat-resistant than PLA, easier to print than ASA, and handles many chemicals well. Only in long-term, intense sunlight does ASA perform better. For functional indoor parts, PETG is therefore often the smartest choice. You can read the comparisons in PLA vs PETG and ASA vs PETG. Want to see all materials side by side? Then check out how to choose the right filament for your print.
Choosing the right material is only half the battle. An ASA part with walls that are too thin or a clamp designed just a bit too tight will still break. Not sure if your file is ready to print? Get it checked for printability for free. You'll receive personal advice on materials and settings within 48 hours. Don't have a file yet? You can also have your idea modeled.
Frequently asked questions about PLA vs ASA
Is ASA stronger than PLA?
That depends on what you mean by strong. PLA has higher tensile strength, but it's brittle and will snap under impact. ASA is tougher and handles shocks and vibrations much better. For parts used outdoors or under load, ASA is usually the stronger choice in practice.
Can you use PLA outdoors?
For a short time, yes, but not for years. PLA fades in the sun, becomes brittle, and can warp in hot weather. For anything that will be outside for more than a season, ASA is the better choice.
Is ASA toxic?
A finished ASA print is safe to touch and use. During the printing process, however, fumes are released, including styrene. That’s why ASA should be printed in an enclosed printer with good ventilation. If you have us handle the printing, you don't have to worry about that.
Is ASA more expensive than PLA?
Per kilo, ASA is usually the same price to about 50% more expensive than PLA, depending on the brand and retailer. For a standard print, the difference in filament cost is often less than a euro. The bigger difference lies in the print time and the extra care that ASA requires.
Which filament should you choose for car parts?
ASA. A car interior in the sun can easily exceed 60°C in the summer, which is enough to warp PLA. ASA remains dimensionally stable up to around 95°C and won't fade behind the windshield.