A spool on the scale weighs more than the filament on it, because the spool itself is not weightless. This subtracts the spool and tells you how much filament is really left, in grams and in metres.
How to use it
- Weigh the spool as it is now and enter the total weight.
- Enter the empty spool weight, from the presets or by weighing a finished one.
- Add the filament diameter and material to get length as well as weight.
- Read the remaining filament: enough for the next print, or time to reorder.
What it does
Subtracts the spool
The number that matters is filament, not filament plus cardboard. This gives you the first.
Weight and length
Grams tells you cost, metres tells you whether the print will finish. You get both.
Spool presets
Common empty-spool weights are built in, so you do not have to hunt for the figure.
What people use it for
Will it finish?
Your slicer says the print needs 180g. Weigh the spool, subtract, and know before you press print instead of at hour nine.
Reorder timing
Track which spools are running low so you restock before you run dry mid-job.
Costing a part
Remaining weight plus a spool price gives you an accurate cost per gram for what is left.
Good to know
- Weigh spools on a kitchen scale to the gram: a 5g error is meaningless on a full spool and matters on an empty one.
- Keep a note of each brand's empty spool weight the first time you finish one. It rarely changes for that brand.
- Length depends on diameter and density, so set the material: PLA and PETG give different metres for the same grams.
- Cardboard spools soak up moisture and gain a little weight over time. For dried filament this is small, but it exists.
Questions
How do I tell how much filament is left on a spool?
Weigh the whole spool, subtract the weight of the empty spool, and what remains is the filament. Enter both here and it does the subtraction and converts to length.
How much does an empty spool weigh?
It varies by brand, usually 130 to 250g for a cardboard or plastic 1kg spool. The tool has common presets, or weigh a spool you have finished and use that number.
Can it tell me the length left?
Yes. Give it the filament diameter and material, and it converts the remaining weight into metres, so you can see if there is enough for the next print.
Why not just use a scale reading?
The scale reading includes the spool. On a nearly empty spool the spool can outweigh the filament, so subtracting it is the whole point.
Also called
Searched as a filament spool calculator, how much filament is left calculator, remaining filament tool, or spool weight calculator. It answers how much you have left before the next print.