PLA vs PETG: which filament should you print with
Quick answer
Print in PLA by default, such as SUNLU PLA ($13.99/kg): it is stiffer, easier to tune, and prints with almost no stringing, which makes it the right choice for indoor decorative pieces and low-stress functional parts. Switch to PETG, such as SUNLU PETG ($15.39/kg), specifically when a part needs to survive heat, moisture or outdoor use, since PETG is tougher and more heat tolerant, at the cost of more stringing and a stronger bond to bare PEI build plates.
SUNLU PLA 3D Printer Filament, Black, 1KG
indoor decor, low-stress parts, beginners and anyone prioritizing print ease
| PLA | PETG | |
|---|---|---|
| Density | 1.24 g/cm3 | 1.27 g/cm3 |
| Stiffness | Stiffer, more rigid | More flexible before failure |
| Toughness | Snaps under sudden stress | Bends and absorbs impact better |
| Water resistance | Absorbs moisture, degrades in humidity over time | Genuinely water resistant |
| Heat tolerance | Softens around 60°C, unsuitable for hot cars | Tolerates noticeably higher temperatures |
| Stringing | Minimal with a well-tuned printer | More prone to stringing between features |
| Bed adhesion to bare PEI | Releases cleanly | Bonds hard enough to tear the PEI sheet without a release agent |
| Ease of printing | Easiest, very forgiving | Needs more tuning, especially retraction |
Why does PETG stick to my bed so hard it tears the PEI sheet?
PETG forms a genuine chemical bond with bare PEI build surfaces, strong enough that peeling a part off can pull up and tear the PEI coating itself rather than releasing cleanly. This is a known property of the two materials together, not a sign anything is set up wrong.
The standard fix is a thin layer of ordinary glue stick applied to the bed before printing, which acts as a release agent and lets the part pop off cleanly once it cools. PLA does not need this on PEI since it releases on its own as the bed cools.
Which filament is actually stronger, PLA or PETG?
It depends on what "stronger" means for the part. PLA is stiffer and holds a shape rigidly under a steady load, but it is more brittle and can snap suddenly under an unexpected impact or sharp bend. PETG is more flexible and absorbs impact and stress better before it fails, which is why it is the better pick for parts that get dropped, flexed, or loaded unpredictably, such as phone mounts or outdoor brackets.
For a part that just needs to hold its shape indoors and never gets knocked around, PLA stiffness is an advantage, not a weakness.
Does PLA actually fall apart in a hot car or on a sunny windowsill?
PLA begins to soften at a temperature that a car interior or a sunny windowsill can reach on a warm day, and a part that softens will sag or warp out of shape, even if it never fully melts. This is one of the clearest reasons to avoid PLA for anything left in a vehicle or against south-facing glass.
PETG tolerates noticeably higher temperatures before softening, which is why it is a common recommendation for phone holders, vent mounts and other parts that live in a car.
Do PLA and PETG weigh differently for the same size spool?
Yes, slightly. PLA has a density of about 1.24 grams per cubic centimeter and PETG is about 1.27 grams per cubic centimeter, so a PETG part of the same volume as a PLA part will weigh a little more. This is a small difference and will not meaningfully change your cost-per-part calculations, but it is worth knowing if you are converting between filament length and weight in a slicer.
PETG
SUNLU PETG Filament 1.75mm,1kg,Black
outdoor brackets, parts near moisture or mild heat, and anything needing more toughness
Both sides of this comparison
- ELEGOO
ELEGOO ABS 3D Printer Filament 1.75mm Black 1KG Strong Layer Adhesion
$16.99 Check pricePrices change often - Polymaker
Polymaker ABS Filament Black 1KG 1.75mm, Heat Resistant, Strength
$17.10 Check pricePrices change often
Safety
Common questions
Can I use the same nozzle temperature for PLA and PETG?
No, PETG needs a higher nozzle temperature than PLA to flow and bond properly between layers, and it usually benefits from a heated bed set higher than PLA needs. Check your specific filament brand for its recommended range rather than reusing PLA settings, since a temperature that is too low for PETG causes weak layer adhesion.
Why does my PETG print have long stringy hairs between parts?
PETG is naturally more prone to stringing than PLA because it stays slightly gooey at a wider temperature range as it cools. Tuning retraction distance and speed, and printing a touch cooler within the recommended range, usually reduces it significantly, though some stringing is normal and can be cleaned up after printing.
Is PETG actually water resistant, or just water resistant compared to PLA?
PETG is genuinely water resistant and is a common choice for parts that get wet, such as outdoor planters or drainage fittings. PLA is not water resistant in the same sense; it can absorb ambient moisture over time and its mechanical properties degrade as a result, which is a separate issue from the printed part directly holding standing water.
Which filament should a beginner start with?
PLA. It prints at a lower temperature, tolerates a wider range of settings without failing, and rarely strings badly even on an untuned printer. Move to PETG once you are comfortable with your printer and have a specific part that needs its toughness or heat resistance.
Do PLA and PETG need to be stored differently?
Both benefit from dry storage since both filaments absorb moisture from the air over time, which causes popping, stringing and rough surfaces during printing. PETG is somewhat less sensitive to this than PLA in casual use, but a sealed container with desiccant is good practice for either one, especially in humid climates.