Bottom line: the real cost per spool includes tare weight, unusable material at the end of the spool, moisture-related losses and rejects. Comparing purchase price alone understates the true cost. Calculate cost per usable kilogram and per good part instead.
Cost elements
| Element | Effect |
|---|---|
| Purchase price | Base cost |
| Tare weight | Shipping and handling |
| End-of-spool waste | Unusable material |
| Moisture losses | Rework and scrap |
| Rejects | Real cost per good part |
Calculation
- Weigh a full spool and an empty spool.
- Estimate end-of-spool waste.
- Divide price by usable net weight.
- Add moisture and handling losses.
- Divide by the good-part yield.
Costly mistakes
- Ignoring tare weight.
- Assuming zero residual waste.
- Ignoring reject rates.
- Not drying the filament.
- Comparing spools of different net weight.
Buyer / engineer checklist
- Is net weight verified?
- Is tare known?
- Is residual waste estimated?
- Is the reject rate known?
- Is cost per usable kilogram calculated?
Tell us your consumption and waste figures and we can help structure the calculation.Purchasing support