Free 3MF to STL Converter

How to convert 3MF to STL

Step 1. Drop your 3MF file on the converter above, or choose it from your device.

Step 2. Look at the preview. If the model lies on its side, change the up direction to match your file.

Step 3. Press the download button. The STL file is saved to your device, named like your original with .stl at the end.

Using a 3MF with software that only reads STL

3MF is the newer print format, but many older slicers, print services, and CAD tools still ask for STL. Converting keeps the shape and drops the extras. Because a 3MF states its unit, the STL comes out at the right size in millimeters.

Colors are not part of an STL, so a multicolor 3MF loses them. If your 3MF has several parts, they all land in one STL. If you need only one part, delete the others in your slicer before you export. Print settings stored in the 3MF are not carried over.

What survives the conversion

Shapes. Every object in the file is read. Shapes are written as triangles in a binary STL.

Colors and materials. Base colors and vertex colors are read. Colors are not kept.

Textures. Most 3MF files hold no textures. Those that do are read. Textures are not kept.

Animation. 3MF cannot hold animation. Animation is not kept, so the model is saved in its first pose.

Units and direction. 3MF files state their unit, and it is read from the file. The file is written in millimeters with Z pointing up, which is what slicers expect. A model with several parts is saved as one file.

If something looks wrong

Print settings stored in the file are ignored. Only the model's shapes and colors are read.

If the file holds a whole build plate, every part on it is read and converted.

If the 3MF used inches, the STL is scaled to millimeters, so a part 2 inches long reads 50.8.

Check the size shown before you print. A part that is 1000 times too big or too small usually means the unit was wrong.

The converter does not repair holes. A printer needs a closed shape, so check the file in your slicer.

If your browser cannot draw 3D, there is no preview, but the conversion still works.

Your file stays on your device

The converter reads your 3MF file in the browser and writes the STL file there too. Nothing is uploaded, and the page does not load anything the file points to, other than files you choose yourself. The page counts a visit like any other page, but it never sees the file's name or contents.