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3D Printer Filament Length Calculator
Convert 3D printer filament weight to length, or length to weight, from its diameter and material density. Weigh a part-used spool to see how many meters are left and whether it is enough for your next print.
Last updated:
g/cm³
Filament diameter
mm
Slicers report filament used as a length (m or mm); enter it here to get the weight and cost.
g
g
Empty spool weights vary by brand. Weighing an empty spool of the same brand gives the best result.
per
g spool
Filament length per kilogram
| Material | Density | Grams per meter | Meters per kg | Feet per kg | Meters per 250 g |
|---|
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How to use the 3D Printer Filament Length Calculator
- Pick the material (or type the density from the datasheet) and the filament diameter.
- Choose a tab: Weight → length, Length → weight or Spool remaining.
- Enter the weight or length. For a part-used spool, weigh it and enter the empty spool weight.
- Optionally add the spool price to see the cost of the filament, and the next print's needs to check you have enough.
- Read the result and compare materials in the table below.
Filament length formula
Filament is a long cylinder, so its weight is simply volume times density:
- Grams per meter = π × (diameter ÷ 2)² × 100 cm × density, with the diameter in cm and the density in g/cm³
- Length (m) = weight (g) ÷ grams per meter
- Weight (g) = length (m) × grams per meter
Example: 1.75 mm PLA has a cross-section of π × 0.0875² = 0.02405 cm². At 1.24 g/cm³ that is 0.02405 × 100 × 1.24 = 2.98 g per meter, so a 1 kg spool holds about 1,000 ÷ 2.98 = 335 m.
Meters of filament per 1 kg spool
| Material | Typical density | 1.75 mm: g/m | 1.75 mm: m per kg | 2.85 mm: g/m | 2.85 mm: m per kg |
|---|---|---|---|---|---|
| PLA | 1.24 g/cm³ | 2.98 | 335 | 7.91 | 126 |
| PETG | 1.27 g/cm³ | 3.05 | 327 | 8.10 | 123 |
| ABS | 1.04 g/cm³ | 2.50 | 400 | 6.63 | 151 |
| ASA | 1.07 g/cm³ | 2.57 | 389 | 6.83 | 146 |
| TPU | 1.21 g/cm³ | 2.91 | 344 | 7.72 | 130 |
| Nylon | 1.14 g/cm³ | 2.74 | 365 | 7.27 | 138 |
| Polycarbonate | 1.20 g/cm³ | 2.89 | 346 | 7.66 | 131 |
Densities are typical values; blends, fillers (carbon fiber, wood, metal, glow-in-the-dark) and brands differ, so use the figure on your filament's datasheet when you have it.
Tips for estimating what's left on a spool
- Weigh, don't guess. A kitchen scale and the empty spool weight give a far better estimate than looking at the spool.
- Note the empty spool weight when you finish a spool, and write it on the next spool of the same brand.
- Slicer lengths are usually filament length, not extruded line length; enter them in Length → weight to compare with what's left.
- Allow a margin of 5 to 10% for purge lines, brims, failed first layers and filament that stays in the extruder and tube.
- Diameter tolerance of ±0.02 mm on 1.75 mm filament changes the length per kilogram by about ±2%.
Frequently asked questions
How many meters of filament are in a 1 kg spool?
For 1.75 mm filament, about 335 m of PLA, 327 m of PETG and 400 m of ABS, because ABS is less dense. For 2.85 mm filament a 1 kg spool holds roughly 120 to 150 m, depending on the material.
How do you calculate filament length from weight?
Work out the weight of one meter: π × (diameter ÷ 2)² × 100 cm × density, with the diameter in cm and density in g/cm³. Then divide the filament weight by that figure. For 1.75 mm PLA one meter weighs about 2.98 g, so 250 g is about 84 m.
How can I tell how much filament is left on a spool?
Weigh the spool and subtract the weight of the empty spool. Divide the net grams by the grams per meter for your material and diameter. The Spool remaining tab does this for you and tells you whether it covers your next print.
How much does an empty filament spool weigh?
It depends on the brand and spool style. Cardboard spools are often around 120 to 160 g and plastic spools around 170 to 280 g for 1 kg reels. Weigh an empty spool of the same brand for the most accurate result.
Why does ABS give more meters per kilogram than PLA?
ABS has a density of about 1.04 g/cm³, while PLA is about 1.24 g/cm³. A kilogram of the lighter material takes up more volume, so at the same diameter the spool contains more length.
Is 3.00 mm filament the same as 2.85 mm?
Most filament sold as 3 mm actually measures about 2.85 mm. If you can, measure it with calipers at a few points and enter the average, since a small diameter change makes a noticeable difference to length per kilogram.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.
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