3D Print Filament Calculator

The math behind length-to-weight conversion

Filament is a cylinder: volume = π × (radius)² × length. Multiply volume by density to get weight. For 1.75mm filament (radius 0.875mm), 1 meter weighs:

• PLA (1.24 g/cm³): 2.98 g/m
• ABS (1.04 g/cm³): 2.50 g/m
• PETG (1.27 g/cm³): 3.05 g/m
• TPU (1.20 g/cm³): 2.88 g/m
• Nylon (1.13 g/cm³): 2.72 g/m
• Polycarbonate (1.20 g/cm³): 2.88 g/m

A 1 kg spool of PLA contains about 330 meters of filament. A typical Benchy uses ~3 grams; a phone stand ~15-25 grams; a full 200mm vase 50-80 grams.

Diameter accuracy matters more than you think

Filament listed as "1.75mm" is rarely exactly 1.75mm — quality brands hold tolerance of ±0.02-0.03mm. Cheap brands can vary ±0.10mm or worse, which causes:

• Underextrusion when filament is thinner than the slicer assumes
• Overextrusion / blobbing when thicker — also clogs hot ends
• Layer inconsistency on tall prints

Check with a digital caliper at 5 random points along the spool. If variance exceeds ±0.04mm, that's a budget-brand spool — adjust extrusion multiplier in the slicer.

PLA vs ABS vs PETG (the big three)

• PLA: Easiest to print. Strong but brittle. Softens at 60°C (don't leave in a hot car). No fumes, great for indoors. Best for prototypes, decoration, models.
• ABS: Heat-resistant (~95°C), tough, machinable. Requires heated bed and enclosure. Strong fumes — needs ventilation. Best for automotive, mechanical parts, anything that goes outdoors.
• PETG: Tough like ABS, easy like PLA. Heat resistance ~75°C. Glossy finish, food-safe potential (depends on print process). The "do most things" choice for functional parts.

Specialty filaments and their use cases

• TPU (flexible): Phone cases, gaskets, shoe soles. Print slow (20-40 mm/s) with direct drive.
• Nylon: Gears, hinges, friction parts. Strong and slippery. Highly hygroscopic — must be dried.
• Polycarbonate (PC): Highest impact strength of common filaments. Needs 270°C+ hot end and enclosure.
• Carbon-fiber-reinforced (CF): Adds stiffness but abrasive. Use hardened steel nozzles ($30+ vs $5 brass).
• Wood-fill, metal-fill: Aesthetic blends. Treat the carrier (PLA usually) for print settings.

Drying filament — when and how

• Hygroscopic materials (Nylon, PETG, TPU, PC) absorb humidity within hours. Dried-out filament gives crisp prints; wet filament pops and strings.
• Signs of wet filament: Crackling sound during extrusion, bubbles in printed surface, bad bridging, weak layer adhesion.
• Drying methods: Dedicated filament dryer ($40-80, ideal), food dehydrator (works), oven at 50°C for 4-6 hours (PLA: don't exceed 50°C; ABS: 80°C OK).
• Storage: Vacuum bags + desiccant for spools you won't use for a week. Or open spools in a dry box at <20% humidity.

Saving filament: design and slicer tips

• Lower infill from default 20% to 10-15% for decorative parts.
• Use lightning or gyroid infill for similar strength at less material than grid.
• Increase top/bottom layers to 5-6 instead of bumping infill — better strength-to-weight.
• Print hollow + add weight separately for tall thin parts (use single-wall vase mode).
• Slice-time waste check: Cura's preview shows total grams. Compare designs before printing.