Filament Remaining / Empty Spool Calculator
Put the spool on a kitchen scale, subtract the empty spool (tare) weight, and see how much filament is left in grams and metres — plus whether it covers your next print with a safety buffer.
Estimates only. Check numbers against your own slicer, scale and electricity bill. Some links on this page may be affiliate links.
How it works
Remaining mass: remaining g = scale reading − empty spool (tare) weight.
Remaining length: metres = remaining g ÷ grams per metre (same cylinder formula as the length ↔ weight calculator).
Enough for next print? needed with buffer = needed g × (1 + reserve% ÷ 100). Enough when remaining g ≥ that threshold.
Example: scale 750 g, tare 200 g → 550 g left. PLA 1.75 mm at 1.24 g/cm³ → about 184 m. A 60 g print with 5% reserve needs 63 g → enough.
How to weigh
- Weigh an empty spool of the same brand once and save that tare (or pick a preset below).
- Weigh the full spool (plastic + filament) on a kitchen scale — 1 g resolution is fine; 0.1 g is nicer near the end of a roll.
- Cardboard spools can absorb a few grams of moisture; re-tare after long humid storage if you care about the last 10–20 g.
- Community empty-spool databases are useful starting points — weigh your own spool when you can; brands change hubs and cardboard cores.
Common empty spool weights
Community-reported approximations (fetched from theemptyspool.cc, 14 Oct 2026). Treat as starting points, not manufacturer guarantees. Bambu reusable + cardboard refill core often lands ~245–260 g in community reports; we use 253 g as a mid value.
| Brand | Spool | Empty (g) | Source note |
|---|---|---|---|
| Bambu Lab | 1 kg Cardboard | 196 | theemptyspool.cc |
| Bambu Lab | Reusable + refill cardboard core | ~253 | community ~245–260; filamentcalcs.com range |
| Bambu Lab | Reusable bare (no core) | ~210 | community ~208–216 |
| Bambu Lab | High Temp 1 kg | 216 | theemptyspool.cc |
| Prusament | 1 kg Plastic | 201 | theemptyspool.cc |
| Polymaker | 1 kg Cardboard | 155 | theemptyspool.cc |
| Polymaker | 1 kg Plastic | 233 | theemptyspool.cc |
| eSUN | 1 kg Plastic | 224 | theemptyspool.cc |
| eSUN | 1 kg Cardboard | 161 | theemptyspool.cc |
| Hatchbox | 1 kg PLA Plastic | 235 | theemptyspool.cc |
| Sunlu | 1 kg Plastic v3 | 188 | theemptyspool.cc |
| Overture | 1 kg Plastic | 237 | theemptyspool.cc |
| Overture | 1 kg Cardboard | 162 | theemptyspool.cc |
| Creality | 1 kg Cardboard | 170 | theemptyspool.cc |
| Elegoo | 1 kg Cardboard | 158 | theemptyspool.cc |
| Anycubic | 1 kg Cardboard | 125 | theemptyspool.cc |
| Inland | 1 kg Cardboard | 142 | theemptyspool.cc |
Sources
- Empty spool weights: community database theemptyspool.cc (crowdsourced; values vary by batch and cardboard moisture).
- Bambu reusable spool + cardboard refill core range: community reports and summaries such as filamentcalcs.com – Bambu Lab spools (~245–260 g with core). Bare reusable (no core) often ~208–216 g.
- Length uses the same density × cross-section maths as our filament length calculator (PLA 1.24 g/cm³ from manufacturer TDS).
Related: filament length ↔ weight · 3D print cost · AMS purge waste
FAQ
Why does empty spool weight vary so much?
Spools differ by brand, plastic vs cardboard, hub design and whether a refill cardboard core is fitted. Even the same SKU can shift a few grams between batches. Community databases are averages — weigh an empty spool of your brand once and reuse that tare.
Does cardboard absorb moisture?
Yes. Cardboard hubs and outer walls can pick up a few grams in humid air, which slightly raises the “empty” weight and understates remaining filament. Dry storage and re-taring after long humid periods keep the last 10–20 g honest.
What about Bambu reusable spools with a refill core?
A bare Bambu reusable spool (no cardboard core) is often around 208–216 g in community reports. With the cardboard refill core fitted, totals commonly land near 245–260 g. This page uses ~210 g bare and 253 g with core as mid values — override with your own scale reading.
Does the net filament weight on the box include the spool?
No. Spool labels quote net filament (e.g. 1 kg of plastic). The scale reading of a new spool is net filament plus empty spool weight. Subtract tare to get what is left after printing.
How do I turn remaining grams into metres or print cost?
Use the length field on this page (density + diameter), or open the filament length ↔ weight calculator. To cost the remaining filament or a planned print, use the 3D print cost calculator.