Enough Filament Calculator
The 2 a.m. question every printer owner knows: is what's left on this spool going to survive a 14 hour print? Enter what the spool has left and what the slicer says the job needs. You get a straight yes, risky, or no, with the margin in grams instead of a guess.
How the verdict works
The math is short: the print's slicer weight, plus a waste margin for priming and skirts, plus purge for multi-color jobs. That total gets compared against what the spool has left. A print that fits with 3 grams to spare is below this tool's planning margin. That is a caution prompt, not a calculated probability of failure.
The tool uses a planning rule of 8% of the required material, or 10 grams, whichever is bigger. It is not a measured guarantee against runout. Inside that window you get "risky" instead. You can still hit print, but do it knowing the margin, ideally on a job where a runout swap or a failed tail doesn't hurt.
Why spool tails are the risky part
The end of a spool is wound tightest against the core, so it carries the most curl. Feed that through a long PTFE path and resistance climbs right when you have zero slack for error. Opened spools also sit around: the outer layers you printed months ago were fresh, the core layers have been drinking humidity ever since. And "1 kg" spools are not lab instruments. Budget brands can run 10 to 20 g light, which is exactly the margin you were counting on.
None of that means the tail is unusable. It means a 260 g print against 270 g of 8-month-old budget PLA is a gamble, and this tool will call it that instead of nodding along.
Get the "what's left" number right
Garbage in, gamble out. The reliable way to know what a spool holds is a scale: weigh the whole spool, subtract the empty spool weight, and what remains is filament. The Remaining Filament Calculator does the subtraction with estimated empty weights per brand, and the spool weight pages list starting values. A scale and a matching tare help you estimate the amount left; check both before relying on a small margin.
Frequently asked
- How accurate is the slicer's weight estimate?
- Accuracy depends on the model, filament and settings. Compare a sliced estimate with your own completed prints. The extra-material slider is a planning allowance for material excluded from your entered total, not a guarantee. Set it to zero when the total already includes all relevant material.
- How do I find out how much filament is actually left?
- Weigh the loaded spool, then subtract the matching empty spool weight, including any core or parts still on the scale. The Remaining Filament Calculator has estimated empty-spool presets for several brands. Check your own spool's tare before relying on a small remaining margin.
- Can I trust the last few meters of a spool?
- Mostly, with caveats. The tightest winding is at the core, so the last meters hold the most curl and kink stress, and on an opened spool they have been exposed to humidity the longest. On quality filament they usually print fine. On budget spools, the last 20 to 30 g is where tangles and snapped filament show up most.
- What are my options if I'm short?
- Split the model across two plates and print the second part on a new spool. Drop infill a notch, 15% to 10% can save real grams on chunky models. Scale the model down a few percent if dimensions aren't critical. Or plan a runout swap: most modern printers pause on filament runout and let you load a new spool mid-print. Bambu printers with an AMS can even auto-switch to a backup spool of the same material.
- Does this work for multi-color prints?
- Yes. Slicers usually include purge waste in their total estimate for multi-color jobs; if yours shows it separately, put the model weight in the print field and the purge grams in the purge field. The AMS Purge Waste Calculator estimates purge if you don't have a sliced number yet.