Infill Percentage Calculator
Infill Is Where Most of the Material Savings Live
The outer shell of a print — the walls and top/bottom layers — is usually a small fraction of total volume, while the interior is where the infill percentage decides how much plastic actually gets used. Dropping infill from 50% to 20% rarely weakens a part as much as intuition suggests, because the shell carries most of the structural load in typical FDM prints. This calculator shows exactly how much material a given infill percentage consumes against the fully solid alternative.
The Formula
Infill Volume = Internal Volume × (Infill% / 100)
Used Volume = Shell Volume + Infill Volume
Where This Calculation Matters
- Budgeting filament across a large batch — small infill changes compound quickly when printing dozens of identical parts.
- Balancing strength against weight — functional parts that bear load need higher infill than decorative prints, but doubling infill rarely doubles strength.
- Reducing print time indirectly — less material to lay down at the same speed and layer height means a shorter job, on top of the material savings.
- Draft vs. final prints — a quick low-infill draft to check fit and dimensions before committing to a high-infill final print.
Common Infill Guidelines
| Infill | Typical use |
|---|---|
| 0–10% | Visual prototypes, display models, non-load-bearing parts |
| 15–20% | General-purpose prints, standard default for most hobbyist work |
| 25–50% | Functional parts subject to moderate mechanical stress |
| 60–100% | High-strength or load-bearing parts, watertight containers |
These are widely used community conventions rather than fixed engineering rules — actual strength requirements depend on wall count, pattern, and material as well as infill percentage.
Worked Example
For a 100 cm³ model with a 15 cm³ shell, increasing infill from 10% to 50% raises used material from 23.5 cm³ to 57.5 cm³ — a jump in material savings from 76.5% to 42.5% versus a fully solid print.
How to Use This Calculator
- Enter the total model volume in cm³.
- Enter the shell (wall) volume in cm³ — your slicer can report this, or estimate it from wall thickness and surface area.
- Enter the target infill percentage.
- Select Calculate to see the used volume and material saved versus a fully solid print.
Related Calculations
Once you know the used volume, run it through the 3D Print Cost Calculator for the material cost, or the Filament Weight Calculator to convert volume to grams.