3D printer filament is a thin strand of thermoplastic wound on a spool, which a fused deposition modeling (FDM) printer melts in a hot nozzle and lays down layer by layer to build a part. Most spools hold 1 kg of 1.75 mm filament, and PLA, PETG and ABS cover most everyday prints.

Filament is the raw material of FDM 3D printing, the most common kind of home printer. Each material trades ease, strength and heat resistance differently: PLA filament suits models and prototypes, while tougher plastics take over for parts that get warm, wet or knocked.

The short answer

Question Answer
What it is A thermoplastic strand on a spool, melted and extruded by an FDM printer
Diameter 1.75 mm on most current printers; 2.85 mm on some
Standard roll 1 kg of filament, about 335 m of 1.75 mm PLA
Easiest material PLA: 190–230 °C nozzle, no enclosure
Stronger everyday material PETG: 230–260 °C nozzle
Heat and sun ABS indoors, ASA outdoors: 240–270 °C, enclosure
Check before buying Diameter tolerance, data sheet, sealed packaging, spool fit
Store it Sealed with desiccant; dry damp spools before printing

What is 3D printer filament?

3D printer filament is a plastic wire, usually a thermoplastic that softens when heated and hardens again as it cools, sold on a spool for FDM printers. The extruder’s gears grip the strand and push it into the hotend, where it melts and leaves the nozzle as a thin bead that becomes one line of one layer.

Diameter is fixed by the printer. Bambu Lab’s data sheets list 1.75 mm, the size most current consumer machines take, while some printers take 2.85 mm, a size Polymaker also sells. A printer accepts only one; our guide to 1.75 mm filament explains why the two are not interchangeable.

What material is used in 3D printing?

FDM printers use filament, but other printer types use other materials. Resin printers cure a liquid photopolymer with light, layer by layer; our comparison of resin vs filament covers that trade-off. Industrial machines also fuse powders, including metals, which is a different process covered in our guide to metal 3D printing. When someone says “filament,” they mean the FDM strand.

Where to buy 3D printer filament and what to check

You can buy 3D printer filament from printer makers’ own stores, from filament brands and from general retailers, and the spool matters more than the shop. Check five things before you order:

  1. Diameter and tolerance. Match your printer, then look for a stated tolerance: ±0.03 mm for Bambu Lab PLA Basic and ±0.02 mm for most Prusament, against the ±0.05 mm that Prusa calls the industry standard.
  2. A technical data sheet (TDS). A good sheet lists nozzle and bed ranges, drying settings and heat deflection with the test load stated.
  3. Sealed packaging. A vacuum bag with desiccant; Bambu Lab’s data sheets call for printing and storage below 20% relative humidity.
  4. A spool that fits. Bambu Lab’s AMS takes spools 50–68 mm wide and 197–202 mm across, and Bambu Lab strongly advises an adapter ring for cardboard spools.
  5. Nozzle requirements. Bambu Lab calls for a hardened steel nozzle, not brass or stainless steel, with carbon fiber, glass fiber and particle-filled filaments such as glow PLA; see our 3D printer nozzle guide.

Brands differ more in what they publish than in the plastic itself. Our guide to the best filament brands compares 12 makers on tolerance, data sheets and spools.

Keep it dry after you buy

Every filament absorbs some water from the air, and some much more than others. Bambu Lab says standard PLA absorbs little water and tolerates normal storage at 50–60% room humidity, but calls PETG highly hygroscopic; damp spools string, bubble and print weak parts. Keep open spools sealed with desiccant, as our filament storage guide shows, and dry damp ones in a forced-air filament dryer, never a kitchen oven or microwave.

Common 3D printer filament materials at a glance

Range chart of nozzle temperatures for common 3D printer filaments from maker data sheets, from metal-filled PLA at 185 to 215 °C and PLA at 190 to 230 °C up to polycarbonate at 260 to 280 °C and carbon fiber nylon at 260 to 290 °C

Most desktop prints use one of the materials below, and many specialty filaments are PLA or PETG with an additive. Nozzle ranges come from the named maker’s data sheet; each linked guide covers settings and properties in detail.

Material Good for Nozzle temperature (maker) Guide
PLA Models, prototypes, decor 190–230 °C (Bambu Lab) PLA guide
PLA+ and tough PLA Clips, brackets, everyday functional prints 190–230 °C (Polymaker PLA Pro) PLA plus
PETG Strong functional parts, damp spots 230–260 °C (Bambu Lab) PETG temperature
ABS Warm or knocked indoor parts 240–270 °C (Bambu Lab) ABS filament
ASA Outdoor parts in sun 240–270 °C (Bambu Lab) ASA filament
TPU Gaskets, bumpers, grips, phone cases 220–240 °C (Bambu Lab) TPU filament
Nylon Gears, hinges, parts that rub 250–270 °C (Polymaker CoPA) Nylon filament
Polycarbonate (PC) Parts facing heat and impact 260–280 °C (Bambu Lab) Polycarbonate
Carbon fiber filled Stiff jigs, fixtures, brackets 210–240 °C (PLA-CF) to 260–290 °C (PA6-CF), Bambu Lab Carbon fiber filament
PVA Water-soluble supports 220–250 °C (Bambu Lab) PVA filament
Silk PLA Glossy vases, ornaments, gifts 210–240 °C (Bambu Lab) Silk PLA
Wood PLA Wood-look decor and boxes 190–240 °C (Bambu Lab) Wood PLA
Metal-filled PLA Heavy statues, props, trophies 185–215 °C (Proto-pasta) Metal filament
Glow in the dark Markers, toys, night-visible parts 190–230 °C (Bambu Lab PLA Glow) Glow filament
LW-PLA (foaming) RC aircraft, light props 210–260 °C (Bambu Lab PLA Aero) LW-PLA

Multicolor prints come from either a spool with more than one color in the strand, such as gradient or dual-color silk PLA, or a printer that switches between spools during the print. Our guide to multi-color 3D printers compares the hardware options.

How to choose filament for your part

Choose filament by where the part will live and what load it will take, starting with PLA and moving up only when the part needs more. This table gives a starting point for common jobs:

Your part Start with Why
Display models, figures, prototypes PLA Easiest to print, sharp detail
Brackets, hooks, everyday functional parts PETG Stronger in tension than PLA, handles damp spots
Parts near warm electronics or motors ABS or PC Heat deflection of 84 °C (ABS) and 117 °C (PC) at 1.8 MPa
Outdoor parts in full sun ASA UV and heat resistance
Flexible parts, grips, bumpers TPU Bends and absorbs impact
Gears, hinges, sliding parts Nylon Tough and low in friction
Stiff jigs and fixtures Carbon fiber nylon Stiffest common filament, 4,430 MPa modulus
Supports for complex overhangs PVA Dissolves in water; needs a multi-material printer

For the three everyday plastics, our PLA vs PETG vs ABS comparison puts their data sheets side by side, and the strongest filament guide ranks materials by load. Then check that your printer can handle the choice:

  • Enclosure: Bambu Lab recommends an enclosed printer for ABS, ASA, PC and nylon, which need hot beds and warm chambers to avoid warping and layer separation.
  • Hotend temperature: PC and nylon run at about 250–290 °C, so confirm your hotend’s rated maximum.
  • Nozzle: fiber and particle-filled spools need a hardened nozzle.
  • Feeder: Bambu Lab does not recommend soft TPU or brittle and abrasive fiber-filled filaments in its AMS units, so check your feeder’s compatibility list.

How many grams of 3D printer filament are on a roll?

Bar chart of filament roll sizes on makers’ pages: 0.5 kg Bambu Lab PVA, 0.75 kg Fiberlogy PCTG, the standard 1 kg roll, about 335 m of 1.75 mm PLA, 2 kg Prusament and 3 and 5 kg Polymaker PolyLite PLA

A standard roll holds 1 kg (1,000 g) of 3D printer filament, not counting the spool, but makers also sell smaller and larger sizes. Typical sizes on makers’ own pages:

  • 1 kg: Bambu Lab’s standard spool, 200 mm across and 67 mm wide, also sold as a refill without the spool.
  • 0.5 kg: Bambu Lab’s PVA support filament.
  • 0.75 kg: Fiberlogy’s PCTG.
  • 2 kg: Prusament spools, sold alongside standard spools and refills.
  • 3 and 5 kg: Polymaker’s PolyLite PLA.

Length depends on density. One kilogram of 1.75 mm PLA at 1.24 g/cm³ is about 335 m (calculation: 1,000 g ÷ (1.24 g/cm³ × 0.02405 cm² cross-section) ≈ 33,500 cm). ABS, at 1.05 g/cm³, gives about 396 m from the same weight. Before buying a 3 or 5 kg spool, check that it fits your holder or feeder; Bambu Lab’s AMS, for example, takes only spools 197–202 mm across.

Price is compared per kilogram. Standard PLA, PETG and ABS form the cheapest tier, and engineering plastics cost more; our guide to 3D printer filament cost lists maker prices and a cost-per-print formula.

How to change 3D printer filament

Six-step flow for changing filament on a printer: unload while hot, pull the old strand out, feed the new filament, load at 250 °C until the flow is clean, purge at the hotter temperature and update the filament profile

To change 3D printer filament, heat the nozzle, unload the old strand, then feed the new one until it flows cleanly from the nozzle. The routine on the A1, one of the current Bambu Lab 3D printers, is typical:

  1. Unload. Tap Unload on the screen. The printer heats the hotend and, on the A1, cuts the filament.
  2. Pull the old strand out while it is hot. Follow the prompt; Prusa also advises unloading right after a print, while the hotend is still hot.
  3. Feed the new filament. Push it into the tube and toolhead until it stops.
  4. Load. Tap Load. When the nozzle reaches 250 °C (482 °F), push the filament again and confirm once plastic flows smoothly from the nozzle.
  5. Purge at the hotter temperature. When switching from a hotter material to a cooler one, Prusa advises loading the new filament at the old one’s temperature, for example PLA at the PETG or ABS temperature, so it pushes the old plastic out.
  6. Update the filament profile on the printer and in the slicer so the next print uses the right temperatures.

Our guide on how to use a 3D printer puts loading filament in the context of a first print.

The bottom line

3D printer filament is the thermoplastic strand an FDM printer melts and stacks into parts, usually sold as 1 kg rolls of 1.75 mm filament. Start with PLA, move to PETG for tougher parts, ABS or PC for heat, ASA for sun, TPU for flex and nylon for wear. Buy spools with a stated tolerance, a data sheet and sealed packaging, and keep them dry.

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