How to Choose PLA Filament for Your 3D Printer

PLA (Polylactic Acid) is the most popular 3D printing filament for beginners and experienced users alike. It's easy to print, produces minimal fumes, and comes in countless colors and finishes. However, not all PLA filaments are created equal. Understanding the key factors—from diameter and tolerance to price per kilogram and print quality—will help you choose the right filament for your projects and budget.

1. Understand What PLA Is (and When It Makes Sense)

PLA is a biodegradable thermoplastic made from renewable resources like cornstarch or sugarcane. It's known for being easy to print, requiring minimal bed heating, and producing little to no odor during printing.

When to use PLA: PLA is ideal for prototypes, decorative items, educational projects, and parts that won't be exposed to high temperatures or significant mechanical stress. It's perfect for beginners because it's forgiving and doesn't require an enclosed printer or special ventilation.

When not to use PLA: Avoid PLA for parts that need to withstand temperatures above 60°C, outdoor applications exposed to direct sunlight, or components under constant mechanical stress. For these cases, consider PETG or ABS instead.

2. Diameter and Tolerance: 1.75 mm and Consistency

Most modern 3D printers use 1.75 mm diameter filament, though some older or industrial models use 2.85 mm (or 3 mm). Always check your printer's specifications before purchasing.

Tolerance is critical: The diameter tolerance indicates how much the filament can vary from its stated size. Look for filaments with a tolerance of ±0.02 mm or better. For example, a 1.75 mm filament with ±0.02 mm tolerance means the actual diameter can range from 1.73 mm to 1.77 mm.

Why tolerance matters: Inconsistent diameter causes under-extrusion (thin layers, gaps) or over-extrusion (blobs, stringing), leading to poor print quality and failed prints. High-quality manufacturers maintain tight tolerances throughout the entire spool.

3. Spool Weight, Price and True Cost (PKU)

Don't be fooled by the sticker price alone. A $20 spool might seem like a great deal, but if it only contains 0.5 kg of filament, you're actually paying more per kilogram than a $30 spool with 1 kg.

PKU (Price per Kilogram): This metric tells you the true cost of filament by dividing the spool price by its net weight. For example:

• Spool A: $25 for 1 kg = $25/kg
• Spool B: $20 for 0.75 kg = $26.67/kg
• Spool C: $30 for 1.5 kg = $20/kg (best value)

Why PKU matters: Comparing PKU allows you to make fair comparisons between different brands and spool sizes. FilamentRank uses PKU as a key metric to help you find the best value filament for your budget.

Always check the net weight (actual filament weight, excluding the spool) rather than gross weight. Some manufacturers list gross weight, which includes the spool and can be misleading.

4. Print Quality: Winding, Color Consistency and Surface Finish

Winding quality: Well-wound filament spools have consistent, even layers without tangles or loose loops. Poor winding can cause the filament to snag, break, or jam during printing. Look for spools with neat, uniform winding.

Color consistency: High-quality PLA maintains consistent color throughout the spool. Variations in color can indicate inconsistent manufacturing or material mixing, which may affect print quality.

Surface finish options:

• Standard/Matte: Most common, good for general use, easy to post-process
• Glossy: Shiny finish, great for decorative items and display pieces
• Silk/Metallic: Smooth, reflective surface, popular for aesthetic prints
• Transparent: Clear or translucent, ideal for light pipes and decorative elements

Choose the finish based on your project's aesthetic requirements. Note that some specialty finishes may require slightly different print settings.

5. Mechanical Properties and Use Cases

Standard PLA vs PLA+: Standard PLA is rigid and brittle, making it ideal for decorative items and prototypes. PLA+ (or PLA Pro) is a modified version with improved toughness, flexibility, and layer adhesion, making it better suited for functional parts that need to withstand some stress.

Temperature limitations: PLA starts to soften around 60°C and will deform under load at higher temperatures. This makes it unsuitable for parts exposed to heat (like car interiors, electronics enclosures near heat sources, or outdoor items in direct sunlight).

When PLA is sufficient: Prototypes, educational models, decorative items, toys, display pieces, and low-stress functional parts.

When to consider alternatives: Parts requiring high temperature resistance (use PETG or ABS), outdoor applications (use PETG or ASA), or high-impact applications (use PETG or TPU).

6. Brand Reputation and Reviews

Reading user reviews is one of the best ways to gauge filament quality. Look for reviews that mention:

• Consistent diameter and tolerance
• Reliable print quality across multiple spools
• Good surface finish and layer adhesion
• Accurate color matching
• Proper spool winding

Established brands with consistent quality control are generally safer bets than unknown manufacturers, even if they cost slightly more. However, don't dismiss smaller brands—many offer excellent quality at competitive prices.

Pay attention to patterns in reviews. If multiple users report the same issues (like inconsistent diameter or poor winding), consider looking elsewhere.

7. Printer Compatibility and Settings

Before purchasing PLA filament, verify your printer's compatibility:

• Nozzle temperature: Most PLA prints well between 190-220°C. Check the filament manufacturer's recommended range.
• Bed temperature: PLA typically requires 40-60°C bed temperature, though some printers can print PLA without a heated bed using a good build surface.
• Print speed: PLA handles speeds from 40-100 mm/s well, depending on your printer's capabilities.

Use manufacturer-recommended settings as a starting point, then fine-tune based on your printer and specific filament. Each brand and color may require slight adjustments to achieve optimal results.

Keep a log of successful settings for different filaments to speed up future prints and maintain consistency.

8. Simple Checklist Before You Buy PLA

Use this checklist to ensure you're making the right choice: