Pick the wrong filament and you get warped parts, snapped clips, or a printer clogged with stringy mess. PLA and PETG are the two most popular FDM filaments, and they solve different problems. PLA is easy, crisp, and cheap. PETG is tougher, more heat tolerant, and more forgiving under load, but fussier to tune. This guide gives you exact settings, head-to-head data, and a clear rule for choosing.
Quick Takeaways
- Choose PLA for display models, prototypes, and low-stress parts. It prints at 190-220°C, needs no enclosure, and gives the sharpest detail.
- Choose PETG for functional parts, outdoor use, and anything that flexes or sees heat up to roughly 70-75°C.
- PLA is stiffer; PETG is tougher. PLA snaps under sudden stress, while PETG bends first and absorbs impact.
- PETG is harder to tune. Expect stringing, and bed adhesion that can turn too strong on smooth PEI.
| Factor | PLA | PETG | Winner |
|---|---|---|---|
| Ease of printing | Very easy | Moderate | PLA |
| Impact resistance | Low | High | PETG |
| Heat resistance | ~55-60°C | ~70-80°C | PETG |
| Detail and finish | Excellent | Good | PLA |
| Cost per kg | $18-25 | $20-28 | PLA |
What Is PLA?
PLA (polylactic acid) is a thermoplastic made from fermented plant starch such as corn or sugarcane. It is the default filament for most hobbyists because it prints at low temperatures, barely warps, and does not require a heated enclosure.
Strengths: high stiffness, sharp corners, minimal odor, wide color and specialty range (silk, matte, wood-fill, carbon-fiber-fill).
Weaknesses: brittle, softens at around 55-60°C (a parked car in summer can deform it), and degrades under prolonged UV and moisture exposure.
What Is PETG?
PETG (polyethylene terephthalate glycol-modified) is the same polymer family as water bottles, with glycol added to prevent the cloudiness and brittleness of raw PET. It sits between PLA and ABS: easier than ABS, tougher than PLA.
Strengths: impact resistance, chemical resistance, low shrinkage, good layer adhesion, and food-safe base resin (printed parts are not automatically food safe because of layer gaps and nozzle contamination).
Weaknesses: strings and blobs, scratches more easily, absorbs moisture quickly, and sticks aggressively to smooth build surfaces.
PLA vs PETG: Head-to-Head Specifications
| Property | PLA | PETG |
|---|---|---|
| Nozzle temp | 190-220°C | 230-250°C |
| Bed temp | 50-60°C | 70-85°C |
| Glass transition (Tg) | ~60°C | ~80°C |
| Tensile strength | 50-65 MPa | 45-55 MPa |
| Elongation at break | 3-6% | 15-25% |
| Density | 1.24 g/cm³ | 1.27 g/cm³ |
| Shrinkage | ~0.3% | ~0.4% |
| Part cooling fan | 100% | 30-50% |
| Typical print speed | 50-200 mm/s | 40-120 mm/s |
| Enclosure needed | No | No |
| UV resistance | Poor | Good |
| Water absorption | Low-moderate | Moderate-high |
| Chemical resistance | Low | Good |
Values vary by brand and blend. Treat them as typical ranges and check your spool’s datasheet.
Strength and Durability
Stiffness vs. Toughness
PLA has slightly higher tensile strength but extremely low elongation. Load it past its limit and it snaps without warning. PETG stretches 15-25% before failure, so a PETG bracket will bend and often survive an impact that shatters PLA.
Layer Adhesion
PETG prints hotter and bonds more strongly between layers, which matters for parts loaded along the Z axis. PLA parts commonly delaminate at layer lines when stressed in that direction.
Heat Resistance
PLA softens near 60°C. PETG holds shape up to roughly 70-75°C under light load. Neither suits engine bays or dishwashers. For higher temperatures, move up to ABS, ASA, or nylon.
Print Settings That Work
PLA Baseline Profile
| Setting | Value |
|---|---|
| Nozzle | 205-215°C |
| Bed | 60°C |
| Layer height | 0.12-0.28 mm (0.2 mm standard) |
| Cooling fan | 100% after layer 2 |
| Retraction (direct drive) | 0.5-1.5 mm at 25-40 mm/s |
| Retraction (Bowden) | 4-6 mm at 40-60 mm/s |
| Speed | 60-150 mm/s outer walls 40-80 mm/s |
PETG Baseline Profile
| Setting | Value |
|---|---|
| Nozzle | 235-245°C |
| Bed | 75-80°C |
| Layer height | 0.16-0.28 mm (0.2 mm standard) |
| Cooling fan | 30-50% (0% on first layers) |
| Retraction (direct drive) | 0.8-2.0 mm at 25-40 mm/s |
| Retraction (Bowden) | 4-7 mm at 35-50 mm/s |
| Speed | 40-80 mm/s outer walls 30-50 mm/s |
| First layer | Slow (15-25 mm/s), 0.05-0.1 mm extra Z-offset clearance |
Copy-Paste Start G-code for PETG (Marlin/Klipper-style)
M140 S80 ; Set bed to 80°C
M104 S170 ; Preheat nozzle to ooze-free standby temp
G28 ; Home all axes
M190 S80 ; Wait for bed
M109 S240 ; Wait for nozzle at 240°C
G92 E0 ; Reset extruder
G1 Z0.3 F600 ; Lift to purge height
G1 X10 Y10 F3000
G1 X10 Y150 E20 F1000 ; Purge line
G92 E0
Klipper Pressure Advance Starting Points
# printer.cfg: tune with a PA tower for your hardware
[extruder]
pressure_advance: 0.045 # Direct drive PETG: try 0.04-0.06
# PLA direct drive: typically 0.03-0.05
# Bowden: start around 0.5-0.8 for both
pressure_advance_smooth_time: 0.040
Run a pressure advance tower before trusting any value, since results depend on your hotend and filament.
Common Problems and Fixes
| Problem | PLA Fix | PETG Fix |
|---|---|---|
| Stringing | Lower temp 5-10°C, raise retraction | Dry filament, lower temp 5°C, add coasting/wipe, raise travel speed to 150+ mm/s |
| Warping | Rare; clean bed, 60°C | Use 80°C bed, brim, avoid drafts |
| Poor first layer | Lower Z-offset, clean with IPA | Raise Z-offset slightly; too-tight PETG sticks too hard |
| Blobs/zits | Adjust seam position | Enable “avoid crossing perimeters,” lower temp |
| Bed damage | Rare | Use glue stick or textured PEI as a release layer on smooth PEI |
| Brittle parts | Moisture or old spool; dry it | Rare |
Drying Filament
| Filament | Dry Temp | Time |
|---|---|---|
| PLA | 45-50°C | 4-6 hrs |
| PETG | 60-65°C | 4-6 hrs |
Wet PETG is the number-one cause of stringing, popping sounds, and rough surfaces. Store both in sealed bins with desiccant.
Cost, Availability, and Variants
| Category | PLA | PETG |
|---|---|---|
| Standard spool (1 kg) | $18-25 | $20-28 |
| Specialty types | Silk, matte, wood, marble, CF, PLA+ | CF, translucent, glitter, PETG-HF |
| Color range | Very wide | Wide |
| Biodegradability | Industrial composting only | Recyclable (PET stream), not biodegradable |
PLA+ is a toughened PLA blend that narrows the gap with PETG on impact resistance, though it stays near PLA’s heat limit. Test it if you want easy printing with a bit more durability.
Practical Examples and Real-World Use Cases
Best Applications for PLA
- Display models and miniatures: crisp detail, minimal post-processing.
- Design prototypes: fast iteration on form and fit.
- Jigs and templates used indoors at room temperature.
- Cosplay props that will be sanded and painted.
- Educational models in classrooms.
Best Applications for PETG
- Mechanical brackets and printer upgrades: fan ducts, spool holders, and toolheads that need some flex.
- Outdoor items: garden clips, planters, drone mounts, and bike accessories.
- Water-exposed parts: bathroom hooks, aquarium hardware, and sink organizers.
- Enclosures and covers for electronics, where impact tolerance and mild heat resistance help.
- Snap-fit parts and living hinges that must flex repeatedly.
- Protective gear: face shield frames and guards, where clear PETG’s toughness matters.
Rule of Thumb Decision Guide
| If your part needs… | Use |
|---|---|
| Maximum detail and ease | PLA |
| To survive a car interior or warm room | PETG |
| To bend or absorb impact | PETG |
| Tight tolerances with minimal tuning | PLA |
| Outdoor or moisture exposure | PETG |
| Lowest cost and fastest print | PLA |
Which Should Beginners Start With?
Start with PLA. It forgives bed leveling mistakes, needs no fine retraction tuning, and teaches fundamentals without frustration. Move to PETG once your first layers are consistent and you have a part that PLA cannot handle.
Frequently Asked Questions
Is PETG stronger than PLA?
It depends on the type of strength. PLA has slightly higher tensile strength and stiffness, while PETG is far tougher, with higher elongation, better impact resistance, and stronger layer adhesion. For parts that may be dropped, flexed, or heated, PETG is the better choice.
Can PETG and PLA be printed on the same printer?
Yes. Any printer reaching 245°C at the nozzle and 80°C at the bed handles both. Check that your hotend has a PTFE-lined path rated for the temperature, since older PTFE-lined hotends should stay below about 240°C. Purge thoroughly when switching, because residual PLA can burn at PETG temperatures.
Is PETG food safe?
The raw resin is generally food-contact approved, but printed parts usually are not. Layer lines trap bacteria, and brass nozzles may contain lead. For food use, choose a certified filament, a stainless steel nozzle, and a food-safe sealant, and limit use to single-use or dry contact.
Why does PETG string so much?
Moisture and excess heat are the usual causes. Dry the spool at 60-65°C for 4-6 hours, lower the nozzle temperature by 5-10°C, increase travel speed, and tune retraction distance. Reducing flow by 2-3% also helps if you see blobs.
