Filament Calculator: Weight, Length & Volume
Convert between grams, meters, and cm³ for any filament. Enter what you know, pick your material and diameter, and find out whether the spool on your printer will actually finish the job.
Show instructions
1.Pick material and diameter
Choose your filament material (PLA, PETG, ABS, etc.) to load its density, and select your diameter, 1.75 mm or 2.85 mm. If your spool lists a different density on its spec sheet, override the default so the conversion matches your exact plastic.
2.Enter any one value
Type in whatever you know: the grams from your slicer, a length in meters, or a volume in cm³. The calculator fills in the other two automatically using the cross-section and density, so you never have to do the area math by hand.
3.Check against your spool
Enter your print's weight and compare it to what's left on the reel. The tool shows how many meters and grams a full 1 kg spool holds for your material, so you can judge at a glance whether a partly-used spool has enough to finish, ideally with a margin to spare.
Slicers report a print in grams, but spools are sold by weight and measured by length, and the leftover on a half-used reel is anyone's guess. This calculator ties those three numbers together. Weight, length, and volume are all the same physical amount of plastic expressed differently, and once you fix the material density and the filament diameter, converting between them is exact arithmetic, not a guess. Type in any one of the three and you get the other two instantly.
The two inputs that change everything are density and diameter. Density (grams per cm³) is a property of the plastic: PLA is roughly 1.24, ABS around 1.04, PETG about 1.27. Diameter sets the cross-sectional area, so the same length of 2.85 mm filament holds about 2.65 times the plastic of 1.75 mm. Get those two right and the math follows. This tool ships with sensible density defaults per material, but you can override the density with the exact figure from your spool's spec sheet when you want manufacturer-grade accuracy.
The math
Cross-section area: A_cm2 = π × (d_cm / 2)², where d_cm = diameter_mm ÷ 10. For 1.75 mm, A ≈ 0.02405 cm²; for 2.85 mm, A ≈ 0.06379 cm². Weight → Volume: volume_cm3 = mass_g ÷ density_g_cm3 Volume → Length: length_cm = volume_cm3 ÷ A_cm2, then length_m = length_cm ÷ 100 Length → Volume: volume_cm3 = (length_m × 100) × A_cm2 Volume → Weight: mass_g = volume_cm3 × density_g_cm3 Combined weight ↔ length: length_m = mass_g ÷ (density_g_cm3 × A_cm2 × 100), and mass_g = length_m × density_g_cm3 × A_cm2 × 100. Worked example (PLA, density 1.24, 1.75 mm): one meter = 100 cm × 0.02405 cm² = 2.405 cm³ of plastic, × 1.24 = 2.98 g per meter. A full 1 kg spool therefore holds 1000 ÷ 2.98 ≈ 335 m (commonly rounded to ~330 m). At 2.85 mm: 100 × 0.06379 × 1.24 ≈ 7.91 g per meter, so 1 kg ≈ 126 m.
Filament density reference
Filament is sold in two diameters: 1.75 mm (most common) and 2.85 mm (often loosely called "3 mm", used by Ultimaker and some Bowden setups). Cross-section area = pi * r^2. For 1.75 mm: r = 0.875 mm, area = pi * 0.875^2 = 2.405 mm^2 = 0.02405 cm^2. For 2.85 mm: r = 1.425 mm, area = pi * 1.425^2 = 6.379 mm^2 = 0.06379 cm^2. So 2.85 mm filament has about 2.65x the cross-section of 1.75 mm — meaning a given LENGTH of 2.85 mm holds ~2.65x the material (volume and weight), and conversely a given WEIGHT of 2.85 mm filament is ~2.65x SHORTER. This is why diameter must be selected before converting between length and weight. Length-weight conversion: mass(g) = length(cm) * area(cm^2) * density(g/cm^3); equivalently length(m) = mass(g) / (density * area * 100). Example, 1 kg PLA (1.24): 1.75 mm yields ~335 m; 2.85 mm yields ~126 m.
| Material | Density (g/cm³) | 1.75 mm (g/m) | 2.85 mm (g/m) |
|---|---|---|---|
| PLA | 1.24 | 2.98 | 7.91 |
| PLA+ | 1.24 | 2.98 | 7.91 |
| PETG | 1.27 | 3.05 | 8.10 |
| ABS | 1.04 | 2.50 | 6.63 |
| ASA | 1.07 | 2.57 | 6.83 |
| TPU | 1.21 | 2.91 | 7.72 |
| Nylon (PA) | 1.10 | 2.65 | 7.02 |
| PC (Polycarbonate) | 1.19 | 2.86 | 7.59 |
| HIPS | 1.05 | 2.53 | 6.70 |
| PVA | 1.23 | 2.96 | 7.85 |
| Wood-fill PLA | 1.20 | 2.89 | 7.66 |
| Silk PLA | 1.24 | 2.98 | 7.91 |
| Carbon-fiber PLA | 1.30 | 3.13 | 8.29 |
| PP (Polypropylene) | 0.90 | 2.16 | 5.74 |
Good to know
Density is the biggest variable
The whole conversion hinges on density, and 'PLA' is not one number. Standard PLA is about 1.24 g/cm³, but silk PLA, PLA+, matte, wood-fill, and glow-in-the-dark blends differ, and filled materials (wood, carbon, glow) can swing several percent. Use the density printed on your spool's technical data sheet when you have it; our defaults are typical mid-range values, not a guarantee for every brand.
A 'full' spool is rarely exactly 1 kg
Net filament weight has manufacturing tolerance, and spools are sometimes labeled by gross weight including the reel. Diameter tolerance (often ±0.02–0.05 mm) also nudges the grams-per-meter slightly. Treat ~330 m for 1 kg of 1.75 mm PLA as a solid estimate, not a precision measurement, and weigh the spool on a kitchen scale (then subtract the empty-reel weight) when you need to know what's actually left.
This counts plastic, not print time or supports
The calculator converts the raw filament amount. Your slicer's gram figure already includes infill, walls, supports, brim, and purge, which is why you should trust the slicer's number for a specific model. Use this tool to translate that number into length, or to estimate from a length, not to predict how much a model will use before slicing it.
Leave a margin before a long print
Filament can snap, jam, or hide a tangle near the core, and the last few meters on a spool are the most likely to misbehave. If your print needs 320 m and the reel theoretically holds 330, that is not a comfortable margin. For unattended or multi-hour jobs, start with clearly more than the calculator says you need, or plan a spool change.
FAQ
How many meters of filament are in a 1 kg spool?
For standard 1.75 mm PLA (density ~1.24 g/cm³) it's about 335 m, commonly rounded to ~330 m. At 2.85 mm the same 1 kg holds only about 126 m, because the thicker filament packs ~2.65× more plastic per meter. Other materials shift the figure: 1 kg of 1.75 mm ABS is closer to 400 m because ABS is less dense, while PETG is around 327 m. Set your material and diameter in the calculator for the exact number.
How do I convert filament grams to meters?
Divide the weight by the grams-per-meter for your filament. Grams per meter = density × cross-section area × 100. For 1.75 mm PLA that's 1.24 × 0.02405 × 100 ≈ 2.98 g/m, so a 30 g part is about 30 ÷ 2.98 ≈ 10 m. The calculator does this automatically once you pick the material and diameter; just type the grams.
Why does diameter change the weight so much?
Weight scales with cross-sectional area, and area grows with the square of the diameter. Going from 1.75 mm to 2.85 mm multiplies the radius by ~1.63, so the area, and the plastic per meter, by ~1.63² ≈ 2.65. That's why one meter of 2.85 mm PLA weighs about 7.9 g versus 2.98 g for 1.75 mm. Always select the correct diameter or every result will be off by that factor.
Will my partly-used spool finish this print?
Compare the print's weight (from your slicer) against the filament left on the reel. The most reliable way to know what's left is to weigh the spool on a scale and subtract the empty reel weight, then convert that net grams to length here if you prefer thinking in meters. If the numbers are close, leave a margin: filament can tangle or snap near the core, so a print needing 320 m on a nominally 330 m spool is risky.
What density should I use for my filament?
Use the value on your spool's technical data sheet whenever possible. As defaults, PLA ≈ 1.24, PETG ≈ 1.27, ABS ≈ 1.04, ASA ≈ 1.07, TPU ≈ 1.21, Nylon ≈ 1.14, PC ≈ 1.20 g/cm³. Filled or specialty blends (wood, carbon-fiber, silk, glow) can differ by several percent, so override the default density field for those if accuracy matters.
How do I convert filament length to volume?
Multiply the length by the cross-section area. Volume (cm³) = length_in_cm × area_cm², where area = π × (diameter_cm ÷ 2)². For 1.75 mm, area ≈ 0.02405 cm², so 10 m (1000 cm) is about 24.05 cm³. Volume is handy for resin-vs-filament comparisons or for checking a slicer's reported cm³ against its grams.
Does this account for infill, supports, and walls?
No, this is a pure weight-length-volume converter for the filament itself. Your slicer already factors in infill, perimeters, supports, brim, and purge when it reports grams for a specific model, so trust that figure for a real print. Use this calculator to translate between units or to estimate from a known length, not to predict a model's usage before slicing.
Why is my actual usage different from the calculator?
A few reasons. Real spools aren't exactly 1 kg of net plastic, diameter tolerance shifts grams-per-meter slightly, and your true density may differ from the default. There's also unmeasured loss: purge lines, oozing, failed first layers, and the unusable bit clamped at the spool core. Expect estimates within a few percent of reality, and weigh leftover spools when you need certainty.