3D Print Scale vs Strength Calculator
Calculates how rescaling a 3D model changes its material weight, accounting for wall thickness effects. Use it before re-printing at a different size to predict filament use and structural changes.
About this calculator
When you scale a 3D print uniformly, volume — and therefore weight — grows with the cube of the scale ratio. A model scaled to twice its original size uses 8× as much material. The formula applied here is: newWeight = (newScale / originalScale)³ × originalWeight × (1 + (wallThickness / 10) × (newScale / originalScale − 1)). The cubic term handles pure volumetric scaling. The bracketed correction factor accounts for the fact that fixed-thickness walls become proportionally thinner at larger scales (and thicker at smaller ones), slightly shifting the actual weight away from the pure cube relationship. Wall thickness is divided by 10 to normalize it to a fractional contribution. Note that strength does not scale linearly with weight — cross-sectional area governs tensile strength and grows with the square of scale.
How to use
Example: original at 100 %, new scale 150 %, original weight 20 g, wall thickness 2 mm. 1. Scale ratio = 150 / 100 = 1.5 2. Cubic term = 1.5³ = 3.375 3. Base weight estimate = 3.375 × 20 = 67.5 g 4. Wall correction = 1 + (2 / 10) × (1.5 − 1) = 1 + 0.2 × 0.5 = 1.10 5. newWeight = 67.5 × 1.10 = 74.25 g Scaling to 150 % increases material use from 20 g to ~74 g — a 3.7× increase.
Frequently asked questions
Why does doubling the scale of a 3D print use so much more filament?
Because volume scales with the cube of linear dimensions. Double every dimension and you get 2³ = 8 times the volume — and 8 times the material. This surprises many users who expect a roughly 2× increase. Even scaling from 100 % to 120 % produces a 1.2³ ≈ 1.73× volume jump. It is one of the most important factors to check before printing a scaled model, since filament costs can escalate quickly.
How does scaling a 3D print affect its structural strength?
Tensile and bending strength depend primarily on cross-sectional area, which scales with the square of the linear dimension, not the cube. So doubling a print's size gives it 4× the cross-sectional area and significantly more resistance to bending, even though weight increases 8×. However, if you scale down, wall sections can become dangerously thin relative to layer height — sometimes falling below the minimum printable thickness. Always check that walls remain at least 2–3 perimeters wide after scaling down.
When should I change wall thickness instead of just scaling the whole model?
Scaling the entire model changes all dimensions uniformly, which is ideal for decorative or display prints. But for functional parts — brackets, snap-fits, hinges — you often want to keep external dimensions fixed while making walls thicker for strength. In that case, edit the wall count or extrusion width in the slicer rather than scaling the STL. Scaling can also inadvertently push wall thickness below the nozzle diameter, making them impossible to print with a single-pass perimeter.