Tech & PC
How much 3D printer filament do you need for a print?
Filament length, spool usage and material cost from your slicer weight estimate.
Quick answer
Slicers already know the answer in grams — this tool converts that to meters of filament and cost per print. An 85 g PLA part on 1.75 mm filament is roughly 28 meters (PLA density 1.24 g/cm³) and uses 8.5% of a 1 kg spool. At 8/kg that is about .53 in material — supports and brim included if your slicer total includes them.
Filament length
28 m
- Share of 1 kg spool
- 8.5 %
- Material cost
- .53
Use the weight Cura, PrusaSlicer or Bambu Studio shows before printing. Length = volume ÷ cross-section; supports and brim are already in the slicer number if you left them enabled.
How it works
Formula: length (m) = (grams ÷ density) ÷ (π × (diameter/2)²) with consistent units. PETG and ABS change length slightly at the same weight because density differs. Compare PLA spools when buying — bulk 1 kg reels beat 250 g samples on shipping per gram.
The spool on the shelf has been changing while you were not printing. Filament absorbs moisture from the air — PLA slowly, PETG and nylon fast — and wet filament crackles as it extrudes, strings between features and produces parts that snap along the layers. A spool left open for a few months prints noticeably worse than a fresh one, and the printer usually gets the blame. Keep spools in a sealed box with desiccant between jobs, and if one has been out for a long time, dry it at low temperature before writing off the print settings.
Frequently asked questions
How many meters of filament in 1 kg PLA?+
About 330 m for 1.75 mm PLA (1.24 g/cm³). PETG is slightly shorter per kg (~320 m) because it is denser. Use the calculator with 1000 g to see your material.
Where do I get the gram estimate?+
Cura, PrusaSlicer, Bambu Studio and Orca show filament weight in the preview before you slice to G-code. Use that number — do not guess from STL volume unless you enjoy failed spool math.
1.75 mm vs 2.85 mm filament?+
Thicker filament feeds faster on large nozzles but weighs the same per meter of plastic deposited — cross-section area changes, so meters per gram drop. Pick your diameter in the calculator to match the spool.
Should I include supports in the weight?+
Yes if they will be printed — slicer totals include supports, brim and raft when enabled. Toggle them off in the slicer first if you want net part weight only.
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