PETG vs. PLA: Differences and Comparison

PETG, which stands for polyethylene terephthalate glycol-modified, and PLA, meaning polylactic acid, are both thermoplastics, used a lot in 3D printing, also known as additive manufacturing. While we only directly offer PLA at the moment here at Xometry, knowing about both of these materials is important to help you understand what options are out there. There are good reasons why both of them are so popular. They’re compatible with most machines, can both be colored or made transparent, and they’re relatively inexpensive. This article will compare these two materials.

PETG Definition and Comparison to PLA

The “PET” in PETG is a polyester (DuPont Dacron); this was first discovered in 1931, after which it was commercialized as Terylene. The “G” is for glycol, which was added to improve the material’s thermal properties by creating a less uniform polymer chain. “The glycol added stabilizes it and lowers the melting temperature,” Christian tells us. This also lowers the residual stress from cooling. Unlike PLA, PETG is made from materials that derive from crude oil. 

To learn more, see our full guide on All About PETG 3D Printing Filament.

What are the Advantages of PETG Compared to PLA?

• Very flexible
• Fairly chemically stable
• High impact strength (less likely to fracture)
• Abrasion-resistant and tough

What are the Disadvantages of PETG Compared to PLA?

• Not easy to sand
• Needs to be printed at a high temperature (could contribute to machine wear and longer cycles of warming up and cooling down)
• Highly viscous so prone to stringing (needs to be printed slower)
• More expensive than PLA and not as environmentally friendly

PLA Definition and Comparison to PETG

PLA has been around for a very long time. It dates back to the 1930s when it was initially discovered at a DuPont lab. It only became available commercially in the 1980s, though, by Cargill Inc. It’s a polymer (essentially a polyester) that’s related to PET (polyethylene terephthalate). “PLA is a bioplastic made from a variety of plant-based materials originally developed as a biodegradable plastic for single use and other applications,” says Christian Tsu-Raun, the Manual Quoting Team Lead here at Xometry. “Desirable 3D printing attributes are rigidity, low cost, and speed of printing.” The lactic acid it contains can come from pretty much anywhere suitable, including both natural and renewable sources like corn starch and sugar cane. At Xometry, we offer PLA in blue, black, white, and red, as shown in the image below:

To learn more, see our full guide on All About PLA 3D Printing Filament.

What are the Advantages of PLA Compared to PETG?

• Makes parts with great cosmetic quality with FDM (fused deposition modeling) printers
• Ease to post-process and hand-finish prints
• Keeps part accuracy as it has a low chance of warping
• Affordable
• Low viscosity at the nozzle
• Low melting point
• Cools to a hard and durable finish
• Good for hobbyists as well as professionals

What are the Disadvantages of PLA Compared to PETG?

• Parts are more susceptible to moisture and UV
• Less temperature stable than other options
• Not the strongest material (could fracture when bent or twisted)
• It’s anisotropic as its interior layers don’t bond as well as other materials

Comparison Table Between PETG and PLA

The below table provides a side-by-side view of these materials and their properties.

Model strength and resilience are considerably higher for PETG. The cosmetic quality of model surfaces, however, is generally better for PLA.

PETG vs. PLA: Applications Comparison

PETG is better for strength, wear resistance, and chemical resistance. Stressed components and moving parts are better made in PETG. Model parts in moving contact against other components will be more resilient in PETG. Parts that will experience either water, sunlight, or heat exposure will also be better in PETG. PLA is better suited to low-stress, cosmetic applications, and components that require a better finish.

PETG vs. PLA: Part Accuracy Comparison

PLA is better suited to maintaining part precision. This is because of its better printability and lower warping. It should be noted, however, that under steady load, PLA tends to creep. For smaller features, PETG bonds better, as it is more viscous in the melt state and achieves better intra-layer coupling.

PETG vs. PLA: Speed Comparison

PETG is more sensitive to print speed than PLA. Newly extruded material may not stick to the layer below or the last strands if the print speed is high. PLA is more sticky, due to its lower viscosity. This results in PETG model build speeds being lower than PLA.

PETG vs. PLA: Surface Comparison

Both materials produce similar surface finish quality. Although in many cases PLA models look smoother because of the lower melt viscosity.

PETG vs. PLA: Heat Resistance Comparison

PETG has a considerably higher melting point than PLA (180°C for PETG, 165°C for PLA).

PETG vs. PLA: Biodegradability Comparison

PETG is derived from crude oil and is environmentally stable. Its life in landfills is measured in centuries. It does experience some degree of UV degradation, shortening the breakdown. PLA is a fragile polymer, and its environmental resistance is so short that it can influence the shelf life of the packaged product.

PETG vs. PLA: Toxicity Comparison

PETG and PLA meet the GRAS (Generally Recognized As Safe) standard and are food safe. Two considerations may influence the application of FDM/FFF parts in food safety terms:

1. Depolymerization occurs when plastics are overheated, producing non-food-safe results. This is more likely to occur in the case of PLA, as the polymer chains are more prone to scorching during extrusion.
2. Coloring agents used in the polymers are likely to NOT be food-safe – and PLA may allow these dye agents to leak.

These factors do NOT imply that printed parts are not food safe. But care should be taken to minimize the use of FDM and FFF parts in food contact.

PETG vs. PLA: Cost Comparison

PETG has a typical cost range of $20 to $25 per kg. This depends on the material class, supplier, and volume purchased. Standard PLA, on the other hand, costs around $15 to $20 per kg.

What are the Mutual Alternatives to PETG and PLA?

Below are the mutual alternatives to both PETG and PLA:

1. ABS: Acrylonitrile butadiene styrene (ABS) is a popular alternative to both PETG and PLA. It can produce good quality, high-strength models. Although, there's a risk of warping and strong smell, requiring tight control of settings. ABS is also much harder to use than either PETG or PLA.
2. ASA: Acrylonitrile styrene acrylate (ASA) is related to ABS, except that it has greater UV resistance, making it ideal for outdoor uses. ASA suffers the same setup and printing issues as ABS and they are both considered good alternatives to both PETG and PLA.
3. PC: Polycarbonate (PC) is also an alternative to PETG and PLA. It has high clarity but requires high-temperature extrusion, limiting its application.

What are the Similarities Between PETG and PLA?

PETG and PLA do have similarities that are significant:

1. Their extrusion temperatures are within 15°C of each other, making them interchangeable on most machines.
2. They can both be transparent or colored.
3. They are the low-cost materials of choice for the majority of FDM/FFF modeling.

Disclaimer

The content appearing on this webpage is for informational purposes only. Xometry makes no representation or warranty of any kind, be it expressed or implied, as to the accuracy, completeness, or validity of the information. Any performance parameters, geometric tolerances, specific design features, quality and types of materials, or processes should not be inferred to represent what will be delivered by third-party suppliers or manufacturers through Xometry’s network. Buyers seeking quotes for parts are responsible for defining the specific requirements for those parts. Please refer to our terms and conditions for more information.