Convert STEP and 3MF to STL
Turn a STEP, STP, 3MF, OBJ or GLB file into an STL you can slice, free and with nothing to install. 3MF, OBJ and GLB files are converted in your browser and never leave your device. STEP files are converted on our server and deleted straight away.
Your STL
Print it at fairfab. See what this part costs to print in PLA or PETG, collected free from Dalston or delivered in the UK.
This uploads the STL so we can measure it. It's deleted straight away.
Drag to turn, scroll or pinch to zoom.
Parts in this file
Untick a part to hide it.
Your part
This part is under 10 mm across. STL and OBJ files have no units, so if it was drawn in inches it's 25.4 times bigger than shown: re-export it in millimetres.
Will it fit your printer?
| Printer | Build volume (mm) | Your part |
|---|
“Turned diagonally” means it fits at an angle on the bed. “On its side” means it fits if you lay it another way up, which can change how it prints.
How the converter works
- STEP and STP. Browsers can't read STEP, so our server turns the exact CAD surfaces into triangles that stay within 0.05 mm of the true shape. The result is a closed mesh, ready to slice. We read the units the part was drawn in and save the STL in millimetres. The file and the mesh are deleted before we reply.
- 3MF. Converted in your browser. A 3MF from Bambu Studio, PrusaSlicer or MakerWorld can hold several objects: save them as one STL with every object where it sits, or as a .zip with one STL per object. 3MF records its units, so the STL comes out in millimetres.
- OBJ and GLB. Also converted in your browser. OBJ files have no units, so we read them as millimetres. GLB (binary glTF) files are in metres with Y up by the standard, so we multiply by 1,000 and turn the model Z up, as slicers expect. If the size looks wrong, pick the units the file was made in before you download.
- What's in the STL. A binary STL in the file's own position, with Z up, holding every part you can see. Untick a part in the parts list to leave it out. Colours and textures are dropped: STL holds shape only.
- Print price. For a STEP file you also see what the part costs to print at fairfab. For other files, press “See the print price”: that uploads the STL so we can measure it, and deletes it straight away.
Do you need to convert?
Not to order from us: send the STEP or 3MF as it is. We price STEP files from the part's exact shape, in the units you drew it in, and we take 3MF files straight from your slicer. Convert when another slicer, printer or service asks for STL. More on each format in STL, STEP or 3MF. To look inside a STEP assembly, measure it or cut a section, use the STEP viewer; to check an STL you already have, the STL viewer and cost calculator.
Questions
How do I convert a STEP file to STL?
Drop the .step or .stp file into the converter above, then press Download STL. Our server turns the CAD model into triangles that stay within 0.05 mm of its true surfaces, and the STL comes out in millimetres, whatever units the part was drawn in. Your CAD program can do the same: look for Export or Save As, then STL.
How do I convert a 3MF file to STL?
Drop it into the converter above. It's converted in your browser, so the file isn't uploaded. If the 3MF holds several objects, as Bambu Studio and MakerWorld files often do, choose one STL with all of them or a .zip with one STL per object. In Bambu Studio or PrusaSlicer, the File > Export menu saves STL too.
Are my files uploaded?
3MF, OBJ and GLB files aren't: they're converted in your browser. STEP files are, because browsers can't read them. Our server converts the file, then deletes it and the mesh before it replies. Nothing is kept. If you ask for a print price, the STL is uploaded so we can measure it, then deleted straight away.
Why is my STL the wrong size?
STL files have no units, so slicers read their numbers as millimetres. STEP and 3MF files record their units, and we convert them to millimetres for you. OBJ files have none, so we read them as millimetres; GLB files are in metres. If the size shown is wrong, pick the units the file was made in before you download.
Can I convert an STL back to STEP?
Not usefully. An STL holds only triangles, so a STEP made from one just wraps the same triangles, with no curves or features to edit. To change a part properly, go back to the CAD file it came from, or redraw it. To 3D print it, the STL is all you need.
Will the STL be ready to print?
STEP files convert to a closed mesh, ready to slice. 3MF files from slicers are usually closed already. OBJ and GLB files made for screens, such as game assets and 3D scans, can have holes or loose surfaces. Open the STL in our STL viewer, which tells you if the mesh has holes, or check it in your slicer.
What is the largest file I can convert?
STEP files up to 30 MB, and 3MF, OBJ and GLB files up to 100 MB. Big files can take a while, especially on a phone.