How to estimate filament for a 3D print
Estimate the weight and length of PLA, PETG, ABS or TPU for a model in STL Viewer, with 1.75 or 2.85 mm filament and your own infill, before you print.
The filament estimate tells you roughly how much material a model will use, as a weight in grams and a length in meters. It helps you decide whether the spool on your printer is enough before you start a long print.
Get an estimate
- Open the model and tap Model info (i) in the top bar.
- Scroll to Filament estimate.
- Choose the Material: PLA, PETG, ABS or TPU.
- Choose the Diameter: 1.75 or 2.85 mm.
- Set the Infill slider from 0 to 100 % to match your slicer. It starts at 20 %.
- Read the Weight and Length. They update as you change the settings.
To start every model with your usual filament, set Filament and Filament diameter in Settings, under Units and filament.
How it is calculated
STL Viewer treats the model as a solid shell 0.8 mm thick (about two 0.4 mm lines, for walls and top and bottom layers) filled with your infill:
- Shell = surface area × 0.8 mm (never more than the whole volume)
- Material = shell + infill × (volume − shell)
- Weight = material × density: PLA 1.24, PETG 1.27, ABS 1.04, TPU 1.21 g/cm³
- Length = material ÷ the cross-section of the filament
Example: a 20 mm cube
Volume 8 cm³, surface area 24 cm². The shell is 24 × 0.08 = 1.92 cm³. With 20 % infill: 1.92 + 0.2 × 6.08 ≈ 3.14 cm³. In PLA that is about 3.9 g, or about 1.3 m of 1.75 mm filament.
Why it is an estimate
Your slicer decides the real amount. Supports, brims, rafts, purge lines, more or fewer walls and the infill pattern all change it. Use the number to compare models or check a spool, not as an exact figure.
The estimate needs a closed mesh. If Model info says the model isn't watertight or has faces pointing inward, the volume, and so the filament, can't be measured reliably.
Check the units first: a model drawn in inches but read as millimeters gives a far too small estimate. Set the right File units in Model info, or scale the model to the size you will print. More on the math in how much filament a print needs.
Learn more on the blog
- Filament Calculator: How Much Filament Will My Print Use?
- Check Your STL Before Printing: An 8-Point Checklist
Questions and answers
Does the estimate include supports?
No. It counts a 0.8 mm shell and your infill for the model itself. Supports, brims and other slicer settings add to the real amount.
Why does it say the filament can't be measured reliably?
The estimate needs a reliable volume. If the mesh has holes, open edges or faces pointing inward, the volume and the filament can't be measured reliably. Repair the model first.
Can I change the default material?
Yes. In Settings, under Units and filament, choose your usual filament and diameter. You can still change them for each model.
More guides
- How to open STL, OBJ, 3MF and PLY files on Android
- How to use view modes and gestures in STL Viewer
- How to check a 3D model's size and volume
- How to measure a 3D model in STL Viewer
- How to see inside a 3D model with Section
- How to scale a 3D model and export it as STL
- How to compare two 3D models side by side
Check your next print on your phone
Free STL, OBJ, 3MF and PLY viewer for Android. Works offline.