Filament costs add up quickly for hobbyists and small businesses. Knowing approximately how much material a print will consume helps you plan purchases and avoid running out mid-project. While slicing software often estimates filament length, this tool lets you convert from model weight directly—useful when weighing completed objects or calculating leftovers on a partial spool.
Most common 3D printing filaments, such as PLA and PETG, have densities around 1.24 g/cm³. Specialty materials may be heavier or lighter. Filament diameter is typically 1.75 mm or 2.85 mm. The cross-sectional area is calculated as , where is the diameter.
Once you know the volume of plastic in your model, dividing by the filament's cross-sectional area gives the length of filament needed. In MathML:
where is model weight in grams, is filament density, is cross-sectional area, and is the extra percentage to account for priming and waste. The result is in centimeters; divide by 100 to convert to meters.
If your model weighs 50 g and you’re using standard PLA with a density of 1.24 g/cm³ and 1.75 mm diameter, the cross-sectional area is approximately 2.405 mm² or 0.02405 cm². The volume is 50 ÷ 1.24 ≈ 40.3 cm³. Dividing by the area yields about 1,676 cm of filament. Adding 10% extra for waste results in roughly 1,843 cm, or about 18.4 m of filament.
Even the best slicers can’t predict every purge, retraction, or failed start. Including a waste factor ensures you have enough filament on the spool. Beginners might use a higher percentage until they refine their printing process.
Weighing the spool before and after printing provides real-world usage data. Keep notes on how much filament each project consumes to refine your settings. If you change materials or nozzle sizes, reevaluate your density and waste values accordingly.
Enter the length remaining on your spool to see how many copies of your model you can print and how much will be left after each one. This simple feature helps you avoid starting a job only to run out of filament halfway through.
This estimator converts model weight to filament length so you can budget materials and plan print jobs effectively. Whether you’re tracking expenses or ensuring you have enough filament for a long print, the simple formula above provides quick guidance.
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