Is there enough filament left for the next print after uncertainty and reserve?
Weigh the loaded spool and subtract a measured identical-spool or manufacturer tare. The conservative decision uses the lower remaining bound, not a generic brand average; length also depends on exact diameter and editable density.
Method
Remaining mass is gross minus tare. Scale and tare uncertainties are added into a bounded range. Filament volume equals mass divided by density, and length equals volume divided by circular cross-section; the next-print gate adds the entered reserve.
Important limitation
Moisture, scale bias, spool revisions, slicer settings, purge/waste, runout sensing and actual extrusion can change the result. Do not use an unverified community tare as exact; weigh an identical empty spool when the decision is close.