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Spool

Spool calculator: how much is left?

Weigh the spool on a kitchen scale, subtract the empty spool, and get the grams, metres and value still on it — without a filament sensor.

Parameters checked 2026-10-23·Dataset sources are listed here; enable JavaScript to load the live list.
JavaScript is switched off. The calculator needs JavaScript. The method below works on paper: remaining grams = gross weight − empty spool weight.
Weigh the whole spool as it stands.
Weigh an empty spool of the same brand. Plastic spools run 150–260 g, cardboard 180–300 g.
1 kg is the common size; 2 kg and 3 kg spools exist too.

Getting the empty spool weight right

  1. Weigh the part-used spool. Write the number down; do not try to remember it.
  2. Find an empty spool of the same brand and material. Weigh it. If you have none, buy the same brand once and weigh it before loading — it is the only unknown in the calculation.
  3. Enter gross and empty weight above. The difference is filament.
  4. If the result says you have more than the spool ever held, the nominal weight in field three is wrong (2 kg spool?) or you mixed up the two weights.

Bambu Lab, Prusament and most cardboard spools publish their empty weight. For everything else, a $10 kitchen scale that resolves 1 g is accurate enough: the error in this method is dominated by the printed spool, not by the scale.

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