🔳 Infill Weight Savings Calculator

Compare estimated print weight at your chosen infill percentage versus a fully solid (100% infill) print, using a simplified shell-plus-infill volume model.

Shell volume (cm³)

Internal (infillable) volume (cm³)

Infill percentage (%)

Material density (g/cm³)

Simplified estimate — actual weight also depends on wall count, top/bottom layers, and infill pattern.

Shell is fixed, only the interior scales

The model splits your part in two: walls and solid top and bottom layers, which print at full density whatever you do, and the interior, filled to the percentage you set.

weight     = (shell + infill% / 100 × internal) × density
solid      = (shell + internal) × density
saved      = solid - weight

With the defaults - 10 cm³ of shell, 40 cm³ of interior, 20% infill, PLA at 1.24 g/cm³ - you get (10 + 8) × 1.24 = 22.32 g against 62.00 g solid. That is 39.68 g saved, or 64.0%.

Infill	Weight	Saved
0%	12.40 g	80.0%
15%	19.84 g	68.0%
20%	22.32 g	64.0%
50%	37.20 g	40.0%
100%	62.00 g	0%

Reading the shape of that table

The first drop is the big one. Solid to 20% removes 39.68 g; 20% to 15% removes 2.48 g. Below 15% you trade real stiffness for grams that barely register.
Your ceiling is the shell fraction. Even at 0% infill this part still weighs 12.40 g, so 80% is the most you can ever save. On a small or thin-walled model the shell dominates and infill hardly matters.
Where the two volumes come from. Slice once at 0% infill and once at 100%: the first figure is the shell, the difference is the interior.

The estimate is linear in infill percentage, which holds well for gyroid, grid and cubic. It ignores wall count and top/bottom layers entirely - a fourth perimeter grows the shell term, not the infill term.

Frequently asked questions

How much filament does 20% infill save?

On a part with 10 cm3 of shell and 40 cm3 of interior, 20% infill weighs 22.32 g against 62.00 g solid - a 64% saving. The proportion depends entirely on how much of your part is wall.

Is 15% or 20% infill better?

For display models 15% is fine and saves 2.48 g on the example above. Functional parts under load benefit more from an extra perimeter than from extra infill, since the walls carry most of the bending stress.

Does infill percentage change print time as much as weight?

No. Infill prints fast in straight lines, while perimeters, top surfaces and travel moves take the bulk of the time. Halving infill cuts far less than half the hours.