Slicers talk in grams, spools are sold in kilograms, and filament is wound in metres. This converts between length and weight for any filament, using the real density of the material, so a number in one unit becomes the number you need in another.
How to use it
- Choose the direction: length to weight, or weight to length.
- Enter the filament diameter (1.75mm or 2.85mm).
- Pick the material, or enter a density from the spool.
- Enter the amount, and read the converted value.
What it does
Both directions
Grams from metres, or metres from grams. Whichever the slicer or the spool gives you, get the other.
Real densities
PLA, PETG, ABS, TPU, nylon and more are built in, so the conversion is right rather than a rough average.
Any diameter
1.75mm or 2.85mm, because the difference is large and getting it wrong throws the answer off by half.
What people use it for
Will the spool finish the print?
Slicer says 190g, spool has 120 metres left. Convert and compare in the same unit before you commit.
Costing by length
Some jobs are quoted by length. Convert to weight to price against what the spool actually cost.
Estimating from a model
Know the filament length a design uses and want the weight for cost? One conversion away.
Good to know
- Density varies a little by brand and colour, especially with fillers like wood or glow additives. For those, use the spool's stated density if it gives one.
- Filled and composite filaments (carbon fibre, wood, metal-fill) are denser: the same length weighs more, so do not assume the base plastic's density.
- Diameter tolerance affects real weight slightly: good filament holds 1.75mm within a few hundredths, which is close enough here.
- For length remaining on a part-used spool, weigh it first with the spool calculator, then convert the remaining grams to metres.
Questions
How do I convert filament length to weight?
It depends on diameter and material density. The tool works out the cross-section from the diameter, multiplies by length for volume, and by density for weight. Choose the material and it uses the right density.
What density should I use?
PLA is about 1.24 g per cubic centimetre, PETG 1.27, ABS 1.04, TPU 1.21, nylon 1.14, ASA 1.07, PC 1.20. The tool has these built in, or you can enter a value from the spool.
How many metres in a 1kg spool?
For 1.75mm PLA, roughly 330 metres. For PETG a little less, for ABS a little more, because density differs. Enter 1000g and your material to see the exact figure.
Does diameter matter much?
A lot. 1.75mm and 2.85mm filament give very different metres for the same weight, because the thicker filament packs more volume per metre. Always set the diameter you use.
Also called
Searched as a filament length to weight calculator, grams to metres converter, filament weight calculator, or filament density calculator. It converts filament between how it is sold and how it is used.