How STL scaling works
Uniform scaling multiplies every dimension by the same factor, so to make one axis a target size:
scale % = target ÷ current × 100
new volume = old volume × (scale ÷ 100)³
Volume — and so filament use and weight — grows with the cube of the scale: printing at 200% uses about 8× the plastic and takes several times longer.
Fixing unit mistakes
| File was made in | Scale to mm |
|---|---|
| Inches | 2540% |
| Centimetres | 1000% |
| Metres | 100000% |
| Millimetres shown as inches | 3.937% |
FAQ
How do I scale an STL to a specific size?
Load it here, pick the axis and type the target size in millimetres. Enter the scale % shown into your slicer's uniform scale field.
My STL is tiny in the slicer — why?
It was probably modelled in inches (or centimetres) and the slicer read the numbers as millimetres. Scale by 2540% for inches or 1000% for centimetres.
Does scaling change print weight proportionally?
No — weight scales with the cube of the factor. 50% size uses roughly 1/8 of the filament, 200% about 8×. Check grams with the STL weight calculator.
Is it OK to scale down small details?
Features thinner than about two line widths (≈0.8 mm on a 0.4 mm nozzle) may disappear or print poorly when scaled down.
Recommended gear
- Digital calipers (150 mm) — Essential for tolerances, flow calibration and checking prints.
- Deburring tool & flush cutters — Clean up holes, edges and supports.
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