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PLA vs PETG vs TPU Filament for Beginners
Quick answer: PLA is the most affordable and easiest to print, making it ideal for first‑time users and simple parts. PETG adds strength and impact resistance at a modest price increase, while TPU gives rubber‑like flexibility but requires more printer tuning and a higher material cost.
1. What These Filaments Are
| Filament | Typical Density* | Common Diameter (mm) | Example Spool Price* |
|---|---|---|---|
| PLA (Polylactic Acid) | 1.24 g/cm³ | 1.75 | $15 / 1 kg (1,000 g) |
| PETG (Polyethylene Terephthalate Glycol) | 1.27 g/cm³ | 1.75 | $20 / 1 kg |
| TPU (Thermoplastic Polyurethane) | 1.20 g/cm³ | 1.75 | $25 / 1 kg |
* Density values are typical manufacturer specifications; please verify on the filament maker’s data sheet.
* Prices are example retail values for a 1 kg (1,000 g) spool sold in the United States. Real‑world prices vary by brand and retailer.
All three are sold on 1 kg spools and use the standard 1.75 mm filament diameter that most hobby printers accept.
2. How Much Filament Do You Actually Use?
A common beginner project – a small phone case – often consumes ≈ 100 g of filament. Below we turn that weight into length for each material, using the standard formula:
Length (m) = (Mass (g) ÷ Density (g/cm³) × π × ((Diameter (mm) ÷ 20))²) × (1 ÷ 100)
The diameter is divided by 20 to convert mm → cm and then halve it for the radius.
Step‑by‑step for a 1.75 mm filament
- Convert diameter to centimeters:
1.75 mm = (1.75 ÷ 10)=0.175 cm
- Find the radius in centimeters:
r = (0.175 ÷ 2)=0.0875 cm
- Compute the cross‑sectional area:
A = π r²=3.1416 × (0.0875)²=3.1416 × 0.00765625≈0.024058 cm²
Now plug the numbers for each filament.
PLA (1.24 g/cm³)
Denominator (density × area):
1.24 g/cm³ × 0.024058 cm²=0.029828 g/cm
Length in centimeters:
(100 g ÷ 0.029828 g/cm)=3,353.5 cm
Length in meters:
(3,353.5 cm ÷ 100)=33.54 m
PETG (1.27 g/cm³)
Denominator:
1.27 × 0.024058 = 0.030558 g/cm
Length (cm):
(100 ÷ 0.030558)=3,273.5 cm
Length (m):
3,273.5 cm ÷ 100 = 32.74 m
TPU (1.20 g/cm³)
Denominator:
1.20 × 0.024058 = 0.028870 g/cm
Length (cm):
(100 ÷ 0.028870)=3,465.5 cm
Length (m):
3,465.5 cm ÷ 100 = 34.66 m
Result: For a 100 g phone case you’ll have roughly 33–35 m of filament, depending on the material.
3. Cost per Print (Material Only)
The cost calculation uses the simple proportion:
Cost = (Grams Used ÷ Spool Weight (g)) × Spool Price
All spools are 1 kg (1,000 g).
PLA
- Fraction of spool used: (100 g ÷ 1,000 g) = 0.10
- Multiply by spool price: 0.10 × \$15 = \$1.50
PETG
- Fraction of spool used: (100 ÷ 1,000)=0.10
- Multiply by spool price: 0.10 × \$20 = \$2.00
TPU
- Fraction of spool used: (100 ÷ 1,000)=0.10
- Multiply by spool price: 0.10 × \$25 = \$2.50
Summary of material cost for a 100 g phone case
| Filament | Material Cost |
|---|---|
| PLA | $1.50 |
| PETG | $2.00 |
| TPU | $2.50 |
4. Adding Electricity Cost
Energy use depends on printer power draw and print time. The slicer (e.g., Cura, PrusaSlicer) gives an estimated print duration; we’ll use 2 hours for the phone case as a realistic example.
Assumed printer power: 150 W (example for a typical mid‑range FDM printer).
Average U.S. residential electricity rate: $0.13 /kWh (U.S. Energy Information Administration, 2023 average).
Step‑by‑step
- Convert watts to kilowatts:
150 W = (150 ÷ 1,000)=0.150 kW
- Multiply by hours to get kilowatt‑hours:
0.150 kW × 2 h=0.300 kWh
- Multiply by electricity rate:
0.300 kWh × \$0.13/kWh= \$0.039
Rounded to the nearest cent, the electricity cost is about $0.04 per 2‑hour print.
5. Printability Overview
| Filament | Recommended Nozzle Temp* | Bed Temp* | Typical Print Speed* | Ease of Tuning |
|---|---|---|---|---|
| PLA | 190‑210 °C | 50‑60 °C (or no heated bed) | 50‑70 mm/s | Very easy – minimal warping, low stringing |
| PETG | 230‑250 °C | 70‑80 °C | 40‑60 mm/s | Moderate – watch for oozing; a little more retraction helps |
| TPU | 210‑230 °C | 40‑60 °C | 20‑30 mm/s (slow) | Challenging – flexible filament can compress in the feeder; use a geared extruder if possible |
* Temperatures are typical ranges from major filament manufacturers; always verify on the specific brand’s data sheet.
6. Strength, Flexibility, and Durability
- PLA – High tensile strength for a brittle material, but low impact resistance. Good for decorative items, prototypes, and low‑stress functional parts.
- PETG – Combines good tensile strength with higher impact resistance than PLA. Slightly flexible, making it suitable for enclosures, mechanical brackets, and outdoor parts that need UV resistance.
- TPU – Elastomeric; can stretch 300 % or more before breaking. Ideal for phone cases, seals, hinges, and any part that must bend repeatedly.
7. Real‑World Scenario: Building a Miniature Robot
Suppose you want a small robot with a sturdy chassis, flexible wheels, and a printed circuit board (PCB) holder. Here’s a material split that balances cost, strength, and flexibility:
| Part | Suggested Filament | Why |
|---|---|---|
| Chassis (load‑bearing) | PETG | Provides impact resistance and can handle the weight of motors and batteries. |
| Wheels & Gear Teeth | TPU (soft) or PETG (hard) | TPU gives a rubbery grip for wheels; PETG works for gears that need dimensional stability. |
| PCB Mounts & Test Pieces | PLA | Cheap and easy to print; perfect for rapid iteration before committing to PETG or TPU. |
Using the calculations above, a 100 g PETG chassis would cost $2.00 in material and $0.04 in electricity, for a total of $2.04. Adding a small TPU wheel (≈ 30 g) adds $0.75 material, bringing the whole robot’s filament cost to under $3.00.
8. How to Choose the Right Filament for Your Project
- Start with the part’s mechanical demands – Does it need to bend, bear load, or resist impact?
- Check your printer’s capabilities – Not all printers handle flexible TPU well; a direct‑drive extruder helps.
- Consider budget – PLA is the cheapest; PETG adds only a modest premium for extra strength.
- Think about post‑processing – PLA sands easily, PETG can be annealed, TPU is difficult to sand.
- Test a small sample – Print a 20 mm cube with the chosen filament; evaluate surface finish, warping, and dimensional accuracy before scaling up.
9. Tips for Beginners
- Level the bed before every print. A well‑leveled bed reduces warping for all three filaments.
- Use the right filament storage – keep spools in a sealed bag with a desiccant to avoid moisture absorption, especially for PETG and TPU.
- Start with slower speeds for TPU (20‑30 mm/s) to avoid skipping steps.
- Enable a cooling fan for PLA; PETG benefits from a moderate fan (30‑50 %); TPU usually prints best with the fan off or at low speed.
- Follow the filament maker’s ventilation guidance – PETG and TPU can emit stronger odors than PLA, so print in a well‑ventilated area.
10. Summary
- PLA – Cheapest, easiest, best for prototypes and decorative items. Approx. $1.50 material cost for a 100 g print, 33.5 m of filament, and $0.04 electricity.
- PETG – Slightly higher cost, adds strength and impact resistance. Approx. $2.00 material cost, 32.7 m of filament, and the same electricity cost.
- TPU – Most flexible, hardest to print, highest material cost. Approx. $2.50 material cost, 34.7 m of filament, and the same electricity cost.
Choosing the right filament is a balance of mechanical needs, printer ability, and budget. Start with PLA to master the basics, then experiment with PETG for functional parts, and finally try TPU when you need true flexibility.
FAQ
1. What should I check about PLA emissions indoors?
Emissions vary by filament and printer; check the filament SDS and maker guidance and ventilate. This site does not make health claims about fumes.
2. Do I need an enclosure for PETG?
An enclosure isn’t required, but it helps maintain a stable temperature and reduces stringing. Follow the printer manufacturer’s recommendations for enclosure use.
3. Why does TPU require slower print speeds?
TPU is flexible, so it can compress in a Bowden‑type feeder. Slower speeds (20‑30 mm/s) give the extruder time to push the filament consistently, reducing jams.
4. How can I calculate the filament cost for a larger print?
Use the formula:
Cost = (Grams Used ÷ 1,000 g) × Spool Price
Plug in the grams reported by your slicer and the price of the spool you purchased.
5. What’s the best way to store PETG and TPU to keep them dry?
Place the spools in airtight containers or zip‑lock bags with silica‑gel packets. Moisture can cause bubbling and poor layer adhesion, especially with PETG and TPU.
For any follow‑up questions, feel free to email us at [CONTACT EMAIL].
Charland & Co. | HobbyPrinter – 3D Printing for Beginners
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