FBX to STL

Printing a game model: FBX to STL

A lot of the models people want to print were never made for printing. Game characters, Mixamo figures, Unity and Unreal assets, and models bought for animation all ship as FBX. Slicers like Cura, PrusaSlicer, Bambu Studio and Chitubox don't open FBX. They want STL, so FBX to STL is the first step to getting that figure onto the build plate.

The converter reads the FBX in your browser, merges everything into one solid STL, and stands it upright for the slicer. No upload, no account.

How to convert FBX to STL

1. Drop the .fbx onto the converter. Textures aren't needed; STL ignores them.

2. Check the pose and the size in the preview. The info panel shows the bounding box in the file's own units.

3. Leave "Fix up axis" on, convert, and download the .stl.

4. Open it in your slicer and scale it to the print size you want.

What happens to the model

STL stores triangles and nothing else. Converting an animated, textured FBX to STL means flattening it into one static shape.

Geometry

Kept. All meshes are merged into one STL, in world space, with every transform baked in. Parts sit where they did in the FBX.

Pose

A rigged character is written in the rest pose stored in the file, which for a rigged character is usually a T-pose. Bones are gone afterwards; the pose is frozen into the triangles.

Textures, colors, UVs

Dropped. STL can't hold them. The print will be one color unless you paint it or split it up in the slicer.

Animation and morph targets

Dropped.

Format

Binary STL by default, which is compact and what every slicer expects. ASCII STL is available if a tool needs it.

The up axis and the scale

FBX treats Y as up, like most game engines. Slicers and CAD treat Z as up. Without a fix, a character comes into the slicer lying on its back. The "Fix up axis" checkbox is on by default for FBX to STL and rotates the model 90 degrees so it stands on the plate. Untick it only if the target tool already handles the rotation.

Scale is the other surprise. STL has no units; slicers read the numbers as millimeters. The converter doesn't rescale anything, so the numbers in the FBX go straight into the STL. A game character modeled in centimeters, 180 units tall, will come out as an 18 cm figure. One modeled in meters will be a 1.8 mm speck. Check the bounding-box size in the preview's info panel, then scale in the slicer to the size you want.

Why a converted game model may not print well

The conversion gives you a valid STL, but game assets are built to look right on screen, not to be solid. Expect some cleanup.

If you want the shape with its UVs for painting or editing, convert FBX to OBJ instead.

Not watertight

Game meshes often have open edges: eyes, mouths, the inside of sleeves. Slicers may fill them oddly. Run the STL through your slicer's repair, Meshmixer, or Blender's 3D Print Toolbox.

Separate overlapping shells

Hair cards, eyeballs, armour and clothing are separate meshes that intersect the body. Most slicers union them when slicing; some don't. Merging them with a boolean in Blender gives the cleanest result.

Paper-thin parts

Capes, leaves and hair cards are single planes with no thickness. They won't print. Add thickness with a Solidify modifier first.

Details too fine

Fingers and accessories that look fine in a game can be thinner than your nozzle at print scale. Scale up or thicken them.

FBX version not supported

FBX 6.x and older can't be read. Convert it with Autodesk's FBX Converter, or re-export it as FBX 7.x from the app that made it.