3D Print Filament Calculator
PLA filament meters and volume from spool weight.
What it does
Slicer grams mean little until they become meters on the spool. A 250 g print can finish a kilo spool or starve mid print depending on diameter and infill. Converting mass to length before slicing avoids cold stops.
The tool above divides mass by grams per meter for PLA. A 250 g length of 1.75 mm stock runs 83.8 m with 201.6 cm3 of plastic, or 0.25 kg of a spool. The imperial match is 8.82 oz toward 275 ft with 12.31 in3.
Rates follow geometry: 1.75 mm needs about 2.9826 g per meter while 2.85 mm needs about 7.9097 g per meter at 1.24 g per cm3. Same grams give far fewer meters on thick stock, which is why small parts favor thin filament.
Density shifts slightly by brand and colorant, and purge lines eat extra. Weigh the spool before long prints and keep a spare when the math lands within a few meters of empty.
How to use
- Pick metric (g, m) or imperial (oz, ft).
- Enter spool mass: 250 g or 8.82 oz.
- Pick 1.75 or 2.85 mm diameter.
- Read filament length first.
- Read volume next.
- Read kg spools for ordering.
Formula
- mass
- Filament mass in g or oz.
- diameter
- Nominal diameter: 1.75 or 2.85 mm.
- 1.24
- PLA density 1.24 g per cm3.
PLA density 1.24 g per cm3 with 1.75 mm cross section gives 2.9826 g per meter, and 2.85 mm gives 7.9097 g per meter. Length divides mass by that rate, volume divides mass by density, and spools divide grams by 1000. Imperial mode converts ounces at 28.3495 g and meters at 3.28084 ft.
Worked example
Example: 250 g of 1.75 mm PLA
Metric defaults: 250 g of 1.75 mm PLA. These are also the default values, so the page opens on this answer.
- Mass: 250 g PLA, 1.75 mm.
- Rate: 2.9826 g per meter.
- Length: 250 / 2.9826 = 83.82, shown as 83.8 m.
- Volume: 250 / 1.24 = 201.61, shown as 201.6 cm3.
- Spools: 250 / 1000 = 0.25 kg.
- Tool shows 83.8 m with 201.6 cm3 and 0.25 kg spools.
- Imperial match: 8.82 oz gives 275 ft with 12.31 in3.
Reference table
| Mass | Length | Volume |
|---|---|---|
| 100 g | 33.5 m | 80.6 cm3 |
| 250 g | 83.8 m | 201.6 cm3 |
| 500 g | 167.6 m | 403.2 cm3 |
| 1000 g | 335.3 m | 806.5 cm3 |
Limits
- PLA at 1.24 density; other plastics differ.
- Ignores purge, prime, and failed prints.
- Nominal diameters; real stock varies.
- Spool tare weight excluded.
Common mistakes
- Weighing the spool with the holder.
- Using 1.75 math for 2.85 stock.
- Trusting label grams exactly.
- Forgetting purge lines.
- Starting a 90 m print on 83.8 m.
Try it yourself
Quick checks. Answers sit tucked under each question.
500 g of 1.75 mm?
167.6 m with 403.2 cm3.
250 g of 2.85 mm?
31.6 m with 201.6 cm3.
Questions
Length in 250 g?
Divide grams by 2.9826 g per meter for 1.75 mm PLA. Here 250 / 2.9826 = 83.8 m.
Volume in 250 g?
Divide grams by 1.24 g per cm3. Here 250 / 1.24 = 201.6 cm3.
Meters per kilo?
About 335.3 m per kilogram at 1.75 mm.
2.85 mm instead?
Thicker stock near 7.9097 g per meter, so 250 g gives 31.6 m.
Exact for every spool?
No. Brands, colorants, and voids shift density slightly around 1.24.
Ounces and feet?
Yes: 8.82 oz converts to the same 250 g toward 275 ft.