Infill Density Weight Calculator
A 3D print is a solid shell wrapped around a partly filled interior. The shell always contains solid plastic, while the interior holds plastic in proportion to the infill percentage. This calculator adds the shell volume to the infill fraction of the interior volume to get the total plastic volume, then multiplies by the material density to estimate the weight in grams. Density is a user-editable input because it varies by material and brand. The result is a transparent estimate; your slicer, which also models top and bottom layers and supports, remains the most accurate source.
Infill weight formula
Infill plastic = interior volume * (infill percent / 100)
Plastic volume = shell volume + infill plastic
Weight (g) = plastic volume * density
Solid weight = (shell + interior) * density
Shell volume is always solid; only the interior is scaled by infill. Comparing against the 100 percent solid weight shows how much material the infill setting saves.
Infill weight context
- Shells stay solid; infill scales only the interior volume.
- Get shell and interior volumes from your slicer, or approximate them from geometry.
- Strength rises with infill but with diminishing returns; wall count often matters more.
- Use your data-sheet density for the material and brand you print.
- Slicers add top, bottom, and support material, so trust slicer output for final figures.
Infill weight: frequently asked questions
How does infill density change print weight?
A print is made of solid shells plus a partly filled interior. The shells are always solid, while the interior holds plastic equal to the infill percentage times the interior volume. Total plastic volume is shell volume plus infill percent times interior volume; mass is that volume times density.
Where do I get shell and interior volumes?
Your slicer can report them, or you can estimate the shell as the part's outer volume minus a hollow core. If you only have the total model volume, set the shell volume to zero and the interior volume to the total, then treat infill as the effective fill of the whole part.
What density should I use?
Use the resin density from your filament's data sheet. Density varies by material and brand, so it is editable here. Typical nominal values are about 1.24 g/cm3 for PLA, 1.27 for PETG, and 1.04 for ABS.
Does higher infill always mean a stronger part?
Strength rises with infill but with diminishing returns, and wall count often matters more for stiffness. This calculator focuses on weight; choose infill based on the load the part must bear and how the walls are configured.
Why might the slicer report a different weight?
Slicers also include top and bottom solid layers, supports, and skirts, and they model infill geometry precisely. This tool gives a transparent estimate from a few volumes; the slicer remains the most accurate source.
Official sources
- National Institute of Standards and Technology: Office of Weights and Measures (mass, volume, density units).
- RepRap project documentation: reprap.org (infill and slicing reference).
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.