Blend to OBJ: Convert a .Blend File to OBJ or STL

A .blend file is Blender's own save file, and almost nothing else can open it. Slicers ignore it, browser viewers reject it, and most converters do not even list it. So if you downloaded a model as a .blend, or someone sent you one, the reliable route is .blend to .obj (or STL) from inside Blender itself. Once you know which export options matter for 3D printing, it takes about a minute.

Below: why the format is so closed, the OBJ and STL exporters, the settings that decide size and orientation, and what to do without Blender.

What is a .blend file?

Blender saves your work by writing its own memory to disk. A .blend file holds Blender's internal data blocks much as they sit in RAM, plus a description of their structure (called SDNA) so a later version of Blender can read them back. Saving is fast and nothing is lost: meshes, modifiers, materials, lights, cameras, animation, even the window layout. Images can be packed inside too.

That is also why a browser cannot open one:

• The layout follows Blender's code. The internal structures change between releases, so a reader has to track Blender's own source.
• The final shape often is not stored. A Mirror, Subdivision Surface, Array or Boolean modifier is saved as a setting, not as triangles. The shape you see only exists after Blender evaluates the modifier stack, and Geometry Nodes can build a whole model from a few inputs. Showing the true result means reimplementing much of Blender.

So a working .blend viewer is hard to find, and the dependable way to view a blend file is to export it once to a common format. (Renaming .blend to .obj converts nothing.)

How to export .blend to .obj in Blender

1. Open the file with File > Open. If it was saved in a newer Blender than yours, update first; older releases may not read newer files correctly.
2. In Object Mode, select what you want to print: click one object and Shift-click the rest, or press A and then deselect cameras, lights and reference objects.
3. Choose File > Export > Wavefront (.obj).
4. Set the options in the panel on the right (below), pick a folder and export.

Blender writes the .obj and, with materials switched on, a .mtl file of the same name next to it.

Exporting STL from Blender

Choose File > Export > STL (.stl). Recent versions (Blender 4.2 and newer) have a native STL exporter built in. Older versions handled STL through a bundled add-on; if STL is missing from your Export menu, open Edit > Preferences > Add-ons, search for "STL" and enable it.

STL keeps only triangles, which is all a slicer needs, and the exporter keeps Blender's Z-up orientation by default, so the model lands upright in the slicer.

Export options that matter for 3D printing

Apply Modifiers

Leave it on (the default). It bakes the modifier stack into the exported mesh, so a mirrored half becomes a whole, a subdivided cage becomes smooth and a posed character keeps its pose, since the armature is a modifier too. With it off you get the raw base mesh, often half a model or a blocky cage.

Selection Only

Called "Selected Only" in the OBJ exporter. Tick it when the scene holds anything you do not want to print, such as a ground plane or reference meshes; otherwise every mesh goes into one file.

Scale and units

This causes more surprises than anything else. OBJ and STL store plain numbers with no unit, and slicers read every number as a millimeter. Blender, out of the box, uses meters with a Unit Scale of 1.0. A figurine modeled at its real height of 0.1 m is written as 0.1 and arrives as a 0.1 mm speck, and the default cube, 2 units wide, prints as a 2 mm cube.

Two clean ways to get it right:

• Work in millimeters from the start. In Properties > Scene > Units, set Unit Scale to 0.001 and Length to Millimeters. One Blender unit is now one millimeter: a 60 mm part reads 60 mm in the sidebar and exports as 60. Keep the exporter's Scale at 1.0.
• Scale on export. If the model was built at real size in meters, set Scale to 1000 in the export panel.

Watch the STL exporter's Scene Unit checkbox. It applies the scene's Unit Scale to the exported numbers, so with the millimeter setup above it shrinks the model a thousand times. Leave it off unless you know you need it, and always check the dimensions after export.

Forward and Up axes

Blender is Z-up, like every slicer. Many other programs treat Y as up, so the OBJ exporter's defaults (Forward -Z, Up Y) rotate the model into that convention. Keep them if you use our OBJ to STL converter or OBJ viewer, which expect Y-up files and stand them upright. If you load the OBJ straight into a slicer and it lies on its back, rotate it there or export with Up set to Z.

Triangulate

OBJ can store quads and n-gons, which slicers split into triangles on import. Ticking Triangulated Mesh makes Blender do the split instead, worth it for n-gons and non-flat quads that different programs may split differently.

Materials and the .mtl file

With Materials > Export ticked, Blender writes a .mtl file with basic colors and links to image textures. The images are referenced, not embedded: send them with the OBJ, or set Path Mode to Copy so Blender copies them into the export folder. Slicers ignore materials, so for printing you can skip all of this.

Which export format to choose

Blender exports GLB through File > Export > glTF 2.0. If your Blender has no 3MF exporter, export STL and convert it with STL to 3MF. Our guide to 3D printing file formats compares them in depth.

How to view a .blend file without Blender

• Ask for an export. If someone sent you the file, ask for OBJ, GLB or STL. GLB is the friendliest for viewing: one file, textures included.
• Check the download page. Model sites often offer several formats; an FBX, for example, opens in the FBX viewer.
• Run Blender in portable mode. Blender is free and open source. On Windows, blender.org offers a portable .zip next to the installer: unzip it, run blender.exe, and nothing is installed. Linux builds also run in place from the archive. Open the .blend, export once, done.

After exporting: view, check and convert

The rest happens in your browser, with nothing uploaded:

• OBJ: check the size and look for holes in the OBJ viewer, then convert with OBJ to STL. If the size is wrong, use Resize longest side.
• STL: open it in the STL viewer to rotate, measure and check that it is watertight.
• GLB: convert with GLB to STL, which turns glTF's meters into millimeters, so a model built at real size in Blender's default units comes out right.
• For your slicer: pack one or more STL files into a 3MF with STL to 3MF, so the units travel with the file.

Common problems and how to fix them

The model is tiny or huge in the slicer

A units mismatch. A model 1000 times too small was usually built in meters, or exported with Scene Unit ticked on a millimeter scene. One 1000 times too big was usually scaled twice. Fix the export settings, or resize the longest side in OBJ to STL.

Missing faces or flipped normals

Inward-facing normals make the slicer treat part of the surface as inside out, which shows up as missing walls. Turn on Face Orientation in the Viewport Overlays menu: blue faces point out, red faces point in. To fix them, select everything in Edit Mode and use Mesh > Normals > Recalculate Outside (Shift+N). A plane with no thickness, like a leaf or a flag, has no volume to print; give it a Solidify modifier.

Non-manifold geometry

Edges shared by more or fewer than two faces, stray vertices and faces buried inside the model all confuse slicers. Find them in Edit Mode with Select > Select All by Trait > Non Manifold. The 3D-Print Toolbox add-on goes further, checking solidity, intersections, wall thickness and overhangs, with a Make Manifold clean-up. Older Blender versions ship it as an add-on to enable in Preferences; in Blender 4.2 and newer, install it from Edit > Preferences > Get Extensions. Then confirm the result in the STL viewer.

Modifiers not applied

Half a model, a low-poly cage or a character in its rest pose means Apply Modifiers was off or a modifier is disabled. Tick Apply Modifiers and check each modifier's viewport and render toggles, or apply them permanently on a copy of the file (hover over a modifier, press Ctrl+A). Convert text and curve objects with Object > Convert > Mesh.

Blend file FAQ

Can I convert .blend to .obj without Blender?

Not reliably. So much of the final shape lives in modifiers and nodes that a correct conversion needs Blender. Portable Blender, or asking the author for an export, is the dependable route.

What is a .blend1 file?

A backup. When you save, Blender keeps the previous version as .blend1 next to the file. Rename it to .blend to open it.

Should I export OBJ or STL for 3D printing?

STL if the model goes straight to a slicer. OBJ if you want separate objects or colors, or plan to open it in other programs. For your own slicer projects, 3MF is the better final format. Starting from scratch instead? See how to make 3D models.