How many meters of filament are in 1 kg?
It's one of the first questions everyone in this hobby ends up googling, and the answer depends on two things: the filament's diameter and its density. For standard 1.75 mm filament, a 1 kg spool works out to roughly:
- PLA (1.24 g/cm^3): about 330 - 335 m
- PETG (1.27 g/cm^3): about 325 m
- ABS (1.04 g/cm^3): about 395 - 400 m - less dense, so you get more length per kilo
- TPU: varies by blend, typically around 1.20 - 1.25 g/cm^3, so close to PLA's length
The math behind those numbers is straightforward: length = weight (density x cross-sectional area). A 1.75 mm filament has a cross-section of about 2.405 mm^2, which is exactly what this calculator uses - enter any weight, diameter, and density and it does the conversion both directions.
Note the spread between materials. ABS gives you about 20% more meters per kilogram than PETG, purely because of density. If you've ever wondered why a "full" spool of one material feels emptier than another, that's why.
How much filament is left on a partial spool?
This is the calculator's most practical job. Slicers tell you a print needs, say, 187 grams - but your spool is half gone and the label only told you what it weighed new. Here's the routine:
- Weigh the partial spool on a kitchen scale.
- Subtract the empty spool's weight. Cardboard spools typically run around 140 - 180 g; plastic and reusable spools (like Bambu's) usually land around 200 - 250 g. If you have an empty one of the same brand lying around, weigh it - that beats any estimate.
- What's left is your remaining filament in grams. Compare it directly against the slicer's estimate, or convert to meters here if your slicer reports length.
A little margin is smart: slicer estimates don't include purge towers, flush waste on multi-color prints, or the skirt. If the print needs 187 g and you have 195 g left, that's a gamble, not a plan.
Why grams-to-meters conversion matters
Filament is sold by weight, but some slicers, printers, and older models report usage by length - and runout sensors don't care about either until it's too late. Being able to flip between the two units means you can sanity-check any estimate against any spool, plan multi-print batches without a mid-print runout, and price jobs from whichever number your slicer hands you. (Speaking of which: once you know the grams, the 3D Print Cost Calculator turns them into a price.)
Filament length FAQ
How many meters of PLA are in a 1kg spool?
About 330 - 335 meters for 1.75 mm PLA at a density of 1.24 g/cm^3. Budget spools occasionally hold slightly less than a true 1,000 g of filament, so treat it as an estimate with a small margin.
How much does 1 meter of filament weigh?
For 1.75 mm PLA, about 3 grams per meter (1,000 g ~333 m). PETG runs slightly heavier per meter, ABS slightly lighter.
How do I know if I have enough filament for a print?
Weigh the spool, subtract the empty-spool weight, and compare the remainder against your slicer's gram estimate - with at least 5 - 10% margin for purge, skirt, and waste.
Does filament diameter change the math?
Massively. 2.85 mm filament has about 2.65x the cross-sectional area of 1.75 mm, so a 1 kg spool holds roughly 125 m instead of 330 m of PLA. The calculator handles both - just set the right diameter.
What density should I enter for my filament?
PLA about 1.24, PETG about 1.27, ABS about 1.04 g/cm^3 - good defaults for standard blends. Filled filaments (carbon fiber, wood, glow) deviate from these, so check the manufacturer's spec sheet when precision matters.
