Filament Weight ⇄ Length Converter Community

What this tool does

Filament is sold by weight but used by length, and the two don't convert the same way for every material — PLA, PETG, ABS, TPU and the rest all have different densities, so a 1kg spool of one material holds a noticeably different length than 1kg of another. Pick a material (or enter a custom density), choose 1.75mm or 2.85mm diameter, enter either a weight in grams or a length in meters, and this tool computes the real weight, length and volume together using the actual cylindrical cross-section of the filament.

How to use it, step by step

1. Choose a material and diameter (or enter a custom density).
2. Enter a known weight in grams or length in meters.
3. Read the converted weight, length and volume.
4. Optionally weigh a spool and enter its gross and empty weight to estimate what's left.

Tips from the guide

• Real filament diameter varies slightly (often ±0.02–0.05mm) from the nominal 1.75 or 2.85mm figure, so treat the converted length as a close planning number rather than an exact one.
• Empty-spool weight varies by brand and material (cardboard vs. plastic vs. reusable spools) — weigh your own empty spool once and reuse that figure for accurate remaining-filament estimates going forward.
• When comparing cost between materials, convert to cost-per-meter or cost-per-cm³ rather than cost-per-kg alone, since denser materials like PETG or nylon pack less length into the same weight than PLA.

Common mistakes to avoid

• Weighing a mostly-empty spool without ever having weighed the bare spool, and guessing the empty weight — even a 20–30g guessing error meaningfully skews the remaining-filament estimate.
• Assuming every filament of the same material has identical density — pigments and fillers (like carbon-fiber or wood-filled blends) shift real density, so use a custom density figure for those if known.
• Mixing up 1.75mm and 2.85mm diameter — the cross-section area (and therefore the length-per-gram) differs by more than double between them.

Who uses it

• Makers checking if a spool has enough filament left for a print. Weigh the spool and get a real remaining length instead of guessing from how full it looks.
• Anyone comparing material costs by length instead of weight. Convert each material's price-per-kg into a real price-per-meter for a fair comparison.
• People buying filament for a specific model. Convert a slicer's reported gram estimate into meters to check it against a spool's remaining length.

How to ask a question people can answer

A good thread on the Filament Weight ⇄ Length Converter saves everyone time. Start with a title that names the exact problem, such as the input you used, the result you expected and the result you got. A title like “Not working” is hard to answer, while a title with the specifics gets replies quickly.

• Say what you tried. List the steps you followed and any settings you changed, so replies do not repeat what you already did.
• Share a small example. A short sample input and the output you saw is worth more than a long description. Remove anything private first.
• Mention your setup. Your device, browser and whether you are on a phone or a computer can explain many odd results.
• One question per thread. Separate topics get clearer answers and are easier to find later with the search box above.
• Come back and reply. If a suggestion worked, say so and upvote it, and if you found the fix yourself, post it for the next person.

Community rules

Be kind, stay on topic and keep personal data out of your posts. Do not post adult, hateful or illegal content, advertising or repeated links. Every post is shown with its author’s username and date, and posts that break these rules can be hidden by moderators. This space is for help with the Filament Weight ⇄ Length Converter and related tasks, and it is separate from the sitewide discussion forum where broader topics live.