PLA or PETG: which should you print in?

These are the two filaments nearly everyone picks between, and most of what’s written about them is somebody’s impression. The numbers below aren’t. They’re printed test pieces of both materials, pulled and hit on the same machine with the same settings, so the two columns can actually be read against each other.

What’s the actual difference?

In one line: PLA is stiff and strong and then it snaps. PETG bends, and keeps bending, and survives.

PLA holds more force before it starts to deform, and it barely flexes while it’s doing it. Drop a PLA bracket on a hard floor and it can break. PETG gives way sooner but puts the force into bending instead of cracking, so an overloaded PETG part goes pale and slightly distorted at the stress point rather than breaking in half. That also means it warns you before it fails.

So a shelf bracket where stiffness is the whole point, PLA. A clip, a hinge, a case, a handle, anything that gets dropped or flexed or sat on, PETG.

What do the test numbers say?

Printed test pieces, pulled and hit in a lab. I’ve put the plain-English version first and the proper name in brackets, because the names are the only hard part.

	PLA	PETG
Force it takes before it starts to give (tensile yield strength)	51 MPa	47 MPa
How stiff it is, bigger is stiffer (tensile modulus)	2.3 GPa	1.5 GPa
How far it stretches before giving (elongation at yield)	2.9%	5.1%
Force to break it by bending (flexural strength)	83 MPa	66 MPa
Hit with a swinging weight (unnotched impact strength)	breaks, at 13 kJ/m²	doesn’t break
Temperature where it starts to soften under load (heat deflection, 0.45 MPa)	55°C	68°C

PLA wins every row except the last two, and those two are the ones that decide most real arguments. The impact row is the single most useful line in the table.

How much heat and weather can each take?

55°C against 68°C sounds academic until you leave something on a windowsill in July or in a parked car. A dark car interior in summer goes past both numbers, so neither of these is a car material, whatever you read. What PETG really gives you is about 13°C more headroom, which covers a sunny window, a shelf above a radiator, or a part that lives next to something warm. Above that you’re into other plastics and a different printer setup.

Outdoors, PETG, clearly. It copes with damp and sunlight far better. PLA outdoors is a slow disappointment rather than a sudden failure. It lasts a season and then goes brittle and chalky, and under constant load it creeps, which means it slowly sags over weeks even at temperatures well below that 55°C. A PLA hook with something hanging on it droops eventually.

Which is easier to print?

PLA, by a distance, and that’s the real reason it’s the default.

	PLA	PETG
Nozzle temperature	210 ± 10°C	250 ± 10°C
Heated bed	40–60°C	80 ± 10°C
Cooling fan	100%	50%
Smooth PEI build plate	fine as it is	needs a glue stick

PLA runs cool, takes full fan, sticks to everything, forgives a slightly-off first layer and barely smells. There’s a reason every printer ships with a sample of it.

PETG is the first filament that asks something of you. It runs 40°C hotter. It wants half the fan, which feels wrong, and too much cooling is the usual cause of weak, hairy PETG. It’s runnier when melted so it oozes more, which leaves fine strands as the nozzle travels. And it picks up moisture from the air faster than PLA, which turns to steam at the nozzle and makes all of that worse.

If your PETG is stringing, work in this order: dry the filament, then drop the nozzle temperature in 5°C steps while it still extrudes cleanly, then adjust retraction. Most people do that list backwards and spend an evening on retraction settings with a damp spool.

The build plate problem

This one costs money, so it gets its own section.

PETG doesn’t just stick to a smooth PEI build plate, it grips it chemically, and when you pull the part off it can take flakes of the plate’s coating with it. That’s not you doing it wrong, it’s how the two materials behave together, and it’s why a smooth PEI plate and PETG only belong together with a glue stick between them. The glue is a release layer, so the part lets go of the glue instead of the plate.

So on a smooth plate, glue stick, every time. On a textured or powder-coated plate it’s a non-issue and PETG comes off cleanly once it’s cool. If you only own a smooth plate and you want to print a lot of PETG, a textured one is cheaper than a wrecked plate.

Which is harder to clean up afterwards?

PETG, which surprises people, because everything it does well in a part works against you once it’s printed.

• Its supports weld on. Supports are the scaffolding the printer builds under overhangs. PETG sticks to itself so well that the support joins to the part instead of resting against it, so sections twist off rather than lift off and leave more behind. There’s a full method in removing supports without marks, and the trick of printing just the top of the support in PLA works because PLA and PETG barely stick to each other.
• It’s harder to cut cleanly. Being tough means flush cutters stretch it rather than shearing it, so you get a pale, drawn-out edge where PLA would give a clean one. Sharp cutters, small bites.
• It sands more slowly. PETG tolerates dry sanding better than PLA because it softens higher, but it’s gummier under the paper. Wet sanding still wins. Same method either way: how to sand a 3D print smooth.
• PLA takes paint more happily. PETG’s surface is slicker, so degrease it properly and use a primer that says plastic on the tin.

So which should you use?

PLA if the part is to look at, to sit indoors, or to be a quick test. Models, figures, desk organisers, a bracket for a bookshelf. Also if you’re learning, because every other problem is easier to work out when the filament isn’t one of them.

PETG if the part has a job involving heat, water, weather, or being dropped, flexed or handled a lot. Phone holders, tool holders, boxes, outdoor mounts, clips, anything living in a shed or a garden.

Whichever is already loaded if the part doesn’t care, which is most prints. On Elegoo’s UK store on 12 October 2026 both were £11.99 a kilo, so price isn’t a tiebreaker either.

Full disclosure: I sell a finishing kit with cutters, files and sanding sponges in it. PETG makes the cutters and files matter more. It won’t make either filament print better.