Scale & Resize STL Files
LocalScale or resize STL/OBJ/PLY/3MF/GLB by a factor or per axis — mm↔inch presets (×25.4), before/after bounding-box check, STL export. Free in browser, no upload.
Drag files here, or click to browse
Supports STL, OBJ, PLY, 3MF, GLB, GLTF
Choose fileScale STL/OBJ/PLY/3MF/GLB and export STL for 3D printing (unit conversion).
What is it? Scale & Resize STL Files scales STL/OBJ/PLY/3MF/GLB/GLTF models by a factor or per-axis (X/Y/Z) values, with mm↔inch presets, and exports STL ready for slicing.
TL;DR: Scale & Resize STL Files resizes STL/OBJ/PLY/3MF/GLB models by a factor or per axis (X/Y/Z), with mm/inch presets and a before/after bounding-box comparison, exporting binary STL. Drop a model and the scaled file downloads automatically. Free with no sign-in; local, nothing is uploaded.
How to use
- Open a model — one file at a time; if several files arrive together only the first is processed and the rest are listed as ignored.
- Enter a scale factor or per-axis (X/Y/Z) scales — use the presets for mm↔inch.
- The scaled STL downloads automatically as <name>-scaled.stl — check the reported before/after bounding-box size (X×Y×Z → X×Y×Z, units = file units); the page also renders the scaled model in a 3D view.
- Need an exact target height rather than a factor? Divide target by the current bounding-box size to get the factor — or open Center STL on the Bed, which scales to a set height and drops the model on the bed.
FAQ
Can I stretch one axis only?
Yes — enter separate X/Y/Z scale factors for non-uniform resizing; use Center STL on the Bed to fit an exact target height.
Is it local?
Yes, scaling runs in your browser.
Which preset should I use, ×25.4 or ×0.03937?
STL carries no units — if the model was modeled in inches but your slicer expects millimeters, use ×25.4 (in→mm); the other way around, ×0.03937. Check the reported before/after bounding-box size before exporting.
Why did my model move after scaling?
It shouldn't — scaling is anchored to the model's geometric (bounding-box center), so off-center parts stay in place. If you need bed placement or a target height, use Center STL on the Bed.
Can I scale to exact dimensions, like 20 mm tall?
Not directly — this tool takes a scale factor (overall or per axis), not a target size. Read the reported before/after bounding-box, divide your target by the current size, and enter that as the factor. If you want to set an exact height and place the model on the bed in one step, use Center STL on the Bed.
Which files can I scale, and what comes out?
Any mesh you can load — STL, OBJ, PLY, 3MF, GLB and glTF. The scaled model is always exported as binary STL, saved as <name>-scaled.stl, since that is what slicers read; materials and colors do not carry over.
Does an STL file store its units?
No — STL has no unit field, it is just coordinates. The same file can be millimeters in one slicer and inches in another, which is why an inch-modeled part prints 25.4× too small. The mm/inch presets here apply the factor so the geometry matches the unit your slicer assumes; confirm the unit in your slicer before printing.
Examples
- Drop in an STL at ×25.4 → inches-to-mm STL
Supported formats
Limitations
- No mesh repair — run Mesh Doctor first for broken meshes.
- STL files carry no unit information: confirm the unit (mm by default) in your slicer.
- Scaling is anchored to the bounding-box geometric center: the center position is unchanged before and after, and the success summary shows the exported filename plus the before/after bounding-box size comparison (X×Y×Z → X×Y×Z, units = file units); the page also renders the scaled model in a 3D view.
- One model at a time: dropping several files processes only the first — the rest are listed as ignored in a notice. Drop them one at a time.
- Exports binary STL (materials/colors are dropped).
- Point-cloud inputs (.xyz/.pcd and faceless PLY) and empty meshes are rejected with a clear message — no empty 0-triangle STL is produced.
- Scaling runs locally in your browser; files are never uploaded.
Privacy
Privacy first: this tool runs entirely in your browser — your input and files never leave your device, and everything is cleared when you close the page.