PLA vs PETG — which filament should you pick for your 3D print?

Roughly 90% of the parts that come through the workshop are printed in either PLA or PETG. The two cover different jobs and asking which is "better" is the wrong question — it's like asking whether wood or steel is better. Depends what you're building. Here's the practical comparison so you can pick the right one before you upload your STL.

The 30-second answer

• PLA for things that live indoors, look nice, and don't have to do real work.
• PETG for anything that will see heat, sunlight, water, or impact.

If you're still not sure after reading those two lines, keep reading.

Strength and impact

PETG is genuinely tougher than PLA. PLA is stiff and rigid — it'll snap under sudden stress before bending. PETG flexes a little before it fails, which means it survives drops, bumps, and being squeezed in a clip far better. For brackets, clips, hinges, parts that snap together, replacement clamps — PETG every time.

PLA is fine for static parts that just need to hold their shape: display models, signs, decorative pieces, prototype shells you'll handle gently.

Heat resistance

This is the big one and it's where PLA fails fast.

• PLA softens around 55-60°C. That's hot tea, a sunny dashboard, the inside of a closed car in summer, a closed loft in July. PLA parts in any of these places will deform quietly and you won't notice until they're already crooked.
• PETG holds shape up to about 75-80°C. Survives car interiors, outdoor sunlight, hot water (cleaning, not boiling), proximity to small motors, anywhere that would kill PLA.

If your part is going outside, near a window, near a heat source, in a vehicle, or anywhere the temperature might climb above body temperature for any length of time — PETG.

UV and outdoor longevity

PLA breaks down in sunlight over weeks to months. The surface chalks, becomes brittle, and eventually crumbles. Outdoor PLA is a temporary solution at best.

PETG holds up for years outside. It's not bulletproof against UV, but it's far better than PLA. For garden furniture parts, outdoor signage, weather-exposed clips and brackets, PETG is the only sensible choice from these two.

Surface finish and looks

PLA wins on appearance, hands down. It prints sharper edges, finer detail, smoother top surfaces, and is easier to sand and paint. If you're printing a model, a figurine, a display piece, anything where looks matter — PLA every time.

PETG has a slightly stringy, slightly glossier finish out of the box. Detail is good but not PLA-good. Sanding is harder; the material is rubbery and clogs sandpaper. Painting works but takes a primer that adheres to PETG specifically.

Ease of printing

PLA is the friendliest material in 3D printing. Sticks to almost any bed, prints at modest temperatures (200-220°C), no warping, no smell.

PETG is fussier. Prints at 230-250°C, can be slightly stringy without good retraction settings, and adheres too well to bare glass beds (you can rip the bed surface off the part if you don't use a release agent or a textured plate). It also absorbs moisture from the air faster than PLA, which causes hissing, popping and surface defects if the spool's been left out for weeks.

For a print bureau like ours these are non-issues — we keep filaments dry-stored and tune for both. For someone printing at home, PLA is more forgiving.

Cost (UK, April 2026)

Per gram, PETG runs about 15-25% more expensive than PLA. At the Hark Tech workshop the surcharge is 20% for PETG over PLA — it's faithfully passed through from filament cost. So a part that's £12 in PLA would be roughly £14.40 in PETG.

For most prints under 100g, the absolute difference is small (a couple of pounds). The cost difference rarely changes the right material choice; pick the right material first, then check the price.

Other materials worth knowing about

• TPU — flexible. For phone cases, gaskets, vibration dampers, anything that needs to bend.
• ASA — like PETG but with even better UV resistance. For long-term outdoor use.
• Nylon, polycarbonate, carbon-fibre composites — engineering-grade for high-stress parts. Specialist printers and dry-stored filament required; ask before assuming a service can run them.

PLA and PETG cover the majority of jobs. Choose between them first; only escalate if neither fits.

Quickest way to choose

| Where will the part live? | Material | |---|---| | Indoors, looks-only | PLA | | Indoors, mechanical (clip, bracket, hinge) | PETG | | Outdoors, any climate | PETG | | In a car, loft, or near heat | PETG | | Display piece you might paint | PLA | | Tool, jig, fixture | PETG | | Replacement plastic part on appliance | PETG | | Cosplay prop you'll handle gently | PLA |

Still unsure? Drop your STL into the Hark Tech printing tool — the price tool shows both PLA and PETG side-by-side so you can compare cost before deciding. If your part needs something neither material covers, the contact form is there too.