Resize and Scale STL Models
Set a percentage scale or type exact width, depth and height values. Use this when a downloaded handle, bracket or figurine needs to become exactly 75 mm wide before slicing.
01 Free browser-based STL editor
Online
STL Editor
Edit STL files directly in your browser. Resize, rotate, mirror, measure, split and export STL models for 3D printing.
Free · No sign-up Files stay on your device Export edited STL
or drop your STL hereBinary & ASCII · processed locally
DRAG TO ORBIT · RIGHT-DRAG TO PAN · SCROLL TO ZOOM02 Modify STL files
Edit STL Files Online
Use this online STL editor to edit STL files directly in your browser. Resize, rotate, move, mirror, measure and split 3D models without installing desktop CAD software.
The editor is designed for practical STL file editing before slicing: change the scale, reorient the model, separate disconnected shells, remove a part, or export a selected component. Files are processed locally, so private models never need to leave your device.
STL files store triangle geometry rather than editable CAD features, so this STL file editor focuses on practical changes you can finish quickly: transform the model, check its size, separate parts, split a section and export a new STL.
03 Simple workflow
How to Edit an STL File Online
- 01
Upload your STL file
Choose a binary or ASCII STL file. It opens locally in your browser.
- 02
Edit the model
Move, rotate, resize, mirror, split or separate parts with precise controls.
- 03
Preview and measure
Orbit the model, check dimensions, and measure point-to-point distances.
- 04
Export the edited STL
Download a standard STL file ready for your slicer or 3D printer.
04 Editor tools
Modify STL Models for Printing
Focused STL file editor controls for quick, printable changes.
Rotate and Reorient STL Files
Rotate by X, Y and Z degrees, use 90 degree shortcuts, lay the model flat, and place it on the build plate when the exported STL opens sideways.
Measure STL Models
Read the bounding box and click two points on the model to measure clearances, pin spacing, socket width or another feature that matters before printing.
Split or Separate STL Parts
Detect disconnected shells, hide, delete or export individual parts, and run a quick plane cut when a multi-object STL needs to be split.
Mirror an STL Model
Mirror along X, Y or Z to turn a left bracket into a right bracket, make paired decorative parts, or create symmetrical layouts.
Free STL Editor for 3D Printing
Use quick browser-based edits before opening Cura, Bambu Studio, PrusaSlicer, OrcaSlicer or another slicer.
05 Exact dimensions
Resize and Scale STL Models
Resize an STL with percentage presets such as 50%, 125% or 200%, or type exact dimensions for width, depth and height. Lock proportions when the model must keep its shape, or unlock them for axis-specific scaling.
Exact size editing is useful when a downloaded STL is modeled in the wrong scale, a miniature needs to fit a specific base, or a functional part must match a known opening. STL does not store real units, so the editor treats dimensions as millimeters and lets you view the same size as mm, cm or inches.
06 Split and separate
Split or Separate STL Parts
Disconnected shells are detected as separate parts, so you can hide, delete or export an individual object from a multi-part STL. The plane cut tool can split a model along X, Y or Z for quick preparation before printing.
Separate Parts works when objects are already disconnected inside the STL. Plane Cut keeps the side you choose along a simple X, Y or Z cutting plane. For sealed cut faces or advanced solid edits, use a dedicated modeling tool.
07 Common edits
What Can You Edit in an STL File?
Most browser edits happen just before slicing: scale, orientation, mirrored variants, part extraction and fit checks.
Make a model the right size
Type an exact width, depth or height when a downloaded STL is too large for your printer or needs to match another part.
Fix orientation before slicing
Rotate a model that opens on its side, lay it flat, then place it on the build plate before exporting the edited STL.
Create left and right versions
Mirror an STL along one axis to create a matching opposite-hand bracket, cover, hook or decorative piece.
Extract one object from a file
When a single STL contains multiple disconnected shells, export only the part you need or delete the extras.
Check fit before printing
Use point-to-point measurement to check holes, tabs, spacing and clearances before spending filament.
Split a quick print section
Use the plane cut when you only need to keep one side of a model or divide a simple section for layout.
08 Browser editing
Free STL Editor for 3D Printing
The editor runs in your browser and is designed for quick STL changes before slicing or printing. Use it before Cura, Bambu Studio, PrusaSlicer, OrcaSlicer or any other slicer when a model needs a simple modification.
- Rotate
- Use XYZ values, 90 degree shortcuts, lay flat and build plate placement.
- Measure
- Check bounding box dimensions and point-to-point distances.
- Mirror
- Create mirrored parts along X, Y or Z while keeping STL export simple.
This is not a sculpting app or full CAD system. It focuses on practical STL edits: transform, measure, separate, cut and export. For broken geometry, use the STL Repair tool.
Need mesh repair? Open STL Repair09 Honest limits
What This STL File Editor Does Not Do
Clear boundaries help you choose the right tool before you spend time editing a mesh.
No sculpting
The editor does not push, smooth, brush or reshape surfaces like a sculpting app.
No CAD constraints
It does not edit sketches, dimensions, fillets, parametric features or design history.
No advanced solid cutting
The plane cut is meant for simple side selection. It does not create new sealed surfaces across complex cuts.
No automatic repair
Editing changes geometry; repairing broken topology belongs in the STL Repair tool.
10 Related workflows
More STL Tools
Inspect, repair, convert and create STL files in your browser.
11 Common questions
STL Editor FAQ
Can I edit an STL file online?+
Yes. Upload an STL file, then use this online STL editor to move, rotate, resize, mirror, measure, split and export the model directly in your browser.
Is this STL editor free?+
Yes. The STL editor is free, requires no sign-up, and does not add watermarks. Your file stays on your device while you edit it.
Can I resize an STL file?+
Yes. You can resize an STL by percentage or by exact dimensions. The editor treats model dimensions as millimeters, with centimeter and inch views for convenience.
Can I measure an STL model online?+
Yes. The editor shows the bounding box and includes point-to-point measurement so you can check distances on the model.
Can I split an STL file into parts?+
Yes. The editor detects disconnected parts and lets you export or delete them. It also includes a simple plane cut for keeping one side of a model along the X, Y or Z axis.
Can I repair a broken STL file?+
Use the STL Repair tool for mesh repair. This editor changes geometry, while STL Repair fixes holes, open edges, non-manifold edges and bad normals.
Do I need Blender or Fusion 360 to edit an STL file?+
Not for common STL edits. Resizing, rotating, mirroring, measuring, separating parts and simple splitting can be done in this browser editor. Sculpting, parametric CAD changes and advanced solid cutting still need a dedicated modeling app.