3D printing with PLA vs. ABS: What's the difference?

PLA and ABS are the two most common materials for prototyping FDM 3D printing (along with PETG). Both are thermoplastics, so the filament softens when heated and returns to a solid when cooled. FDM printers melt and extrude PLA or ABS through a nozzle to build parts layer by layer. 

While both are used for FDM they have key differences that make each better suited to specific applications. This article covers the main differences engineers should consider. 

We also have a Youtube explainer video that compares PLA and ABS filaments. 

What is PLA? Printing with polylactic acid

PLA (polylactic acid) is a thermoplastic derived from renewable sources such as cornstarch or sugarcane. Biodegradable under the right conditions, PLA is a widely used bioplastic for applications ranging from plastic cups to medical implants. 

For FDM 3D printing, PLA is cost efficient and delivers good surface quality. It is easy to print and has higher stiffness than ABS and materials like nylon, but it does not handle high temperatures or significant stress well. PLA can be stronger than ABS and some nylon grades, but it offers limited heat and chemical resistance. 

What is ABS? Printing with Acrylonitrile Butadiene Styrene

ABS (acrylonitrile butadiene styrene) is a common thermoplastic used in FDM 3D printing and widely used in injection molding. Typical applications include toys such as LEGO bricks, housings for electronics, automotive components, and household appliances. 

ABS is tough and impact resistant, with mechanical properties that generally exceed PLA while being lighter and more durable. The tradeoff is more challenging printability and higher processing temperatures. ABS deflects heat more effectively than PLA, but it is not known for high heat resistance. During printing, ABS can produce strong odors. 

What’s the difference between PLA and ABS? 

PLA and ABS differ in tensile strength, density, and typical applications. The table below compares the key material properties of PLA and ABS filaments. 

What is the part accuracy of PLA and ABS?

Dimensional accuracy in FDM depends on machine calibration, process control, and part geometry. PLA and ABS typically achieve about 0.8 mm feature resolution, with minimum feature sizes around 1.2 mm. For connecting or interlocking parts, a typical guideline is 0.5 mm clearance and a minimum wall thickness of 1 to 2 mm to maintain strength across walls. 

Because PLA prints at lower temperatures, it is generally easier to process with less risk of warping when cooled correctly. PLA also supports sharper corners and finer features than ABS. 

How strong are PLA and ABS parts?

PLA and ABS have similar tensile strengths, meaning both can handle comparable loads before breaking. In fact, PLA can often withstand slightly higher loads before snapping, making it a strong material in terms of pure strength.

However, strength alone doesn’t tell the full story. A key difference lies in toughness, the ability of a material to deform without breaking. ABS is significantly tougher than PLA, meaning it can bend and absorb impact before failing, while PLA is more brittle and tends to snap under stress.

This distinction is critical for functional design. For parts that need flexibility or repeated stress, such as clips, snap-fits, or enclosures, ABS is typically the better choice. PLA, on the other hand, is well-suited for rapid prototyping where visual accuracy and ease of printing are more important than mechanical performance.

In general, PLA is a good option for low-load applications that are not exposed to high temperatures or UV radiation. ABS is better suited for more demanding environments, offering improved durability and resistance to physical strain.

How fast can you print with PLA and ABS?

PLA and ABS generally print at similar speeds, so machine speed settings often remain unchanged when switching between these materials. For PLA, 60 mm/s is a common baseline, though print speeds above 150 mm/s are reported in some setups. ABS typically runs at the same speed range, with 40 to 60 mm/s providing more consistent results. 

Surface finishes and post-processing for PLA and ABS

FDM parts have visible layer lines regardless of material. PLA often yields a glossier finish, while ABS tends to appear more matte. Acetone vapor smoothing is commonly used to give ABS a glossy finish. Sanding and secondary machining are viable for ABS, and PLA can also be sanded and machined with additional care. For parts where cosmetic quality is critical, SLA 3D printing is often selected. 

How heat resistant are PLA and ABS?

For higher-temperature applications, ABS is generally preferred over PLA. ABS has a glass transition temperature of around 105°C, while PLA is much lower at approximately 60°C. As PLA approaches this temperature, it begins to lose structural integrity and can soften, droop, or deform, especially under load.

A simple way to understand this is the “hot car test.” If a part is left inside a parked car on a warm day, temperatures can easily exceed 60°C. In these conditions, PLA parts are very likely to warp or fail, while ABS parts will remain stable.

Because of this, PLA is not suitable for outdoor use, high-temperature environments, or applications like engine bays. ABS, on the other hand, is better suited for functional parts that need to maintain their shape under heat and mechanical stress.

Are PLA and ABS biodegradable?

PLA is often described as biodegradable, but this requires important context. While PLA remains stable under normal atmospheric conditions, it only biodegrades under controlled industrial composting conditions, where high temperatures and specific humidity levels are maintained. In these environments, PLA can break down in about 50 days. However, it will not readily decompose in typical home composting or natural outdoor conditions, and can persist for years if improperly disposed of.

ABS, on the other hand, is not biodegradable, but it is recyclable through appropriate waste streams.

For food-related applications, material safety should always be confirmed with the filament supplier and relevant regulations, as not all PLA or ABS filaments are food-safe.