Spool Remaining Estimator
Weigh a partial spool on a kitchen scale and get the actual filament left — not a guess based on how empty the roll looks.
Weigh-in
Typical empty spools: ~210–250g plastic reel, ~140–180g cardboard. Check your brand if known — it's usually printed on the spool or listing.
Filament
Why this beats eyeballing the roll
Filament wound on a spool doesn't shrink in visibly even proportions as it's used, especially past the halfway point, so guessing by looking at roll diameter is unreliable right when it matters most — when you're deciding if there's enough left for one more part. A kitchen scale reading and the spool's known empty weight turns that guess into an actual number.
If you don't know the empty spool weight
Weigh the spool once it's actually empty and write the number on it (tape works fine) — from then on every remaining-filament check for that spool is exact. Until then, the typical ranges in the hint above get you close for most consumer spools.