What Is a .mtl File? .mtl Format, MIME & How to Open

Quick facts

Extension.mtl

File typeMTL 3D Model

MIME typemodel/mtl

Category3D Model

Charset—

Compressible—

What is .mtl

What is a .mtl file?

A .mtl file is a MTL 3D Model. It is a 3D model format used to store meshes, scenes and printing geometry.

In the mime-db registry it maps to model/mtl. When serving .mtl over HTTP, set the Content-Type header as shown in Developer info below.

Related entities: it maps to model/mtl and is used by Wavefront Material among others — and is delivered over HTTP via the Content-Type header.

How to open .mtl files

Use Blender or MeshLab to open and edit .mtl files.
Any text editor (Notepad, VS Code) can inspect the raw content as text.

Developer info

When served over HTTP, responses should set the following header:

Content-Type: model/mtl

Common software that reads/writes .mtl:

BlenderMeshLabAutodesk Viewer

Relation chain

.mtlextension of

format

MTL 3D Modelserved as

mime type

model/mtlsent via header

http header

Related extensions

Related MIME types

Related programming languages

Wavefront Material

.mtl

Common uses

3D printing
Game assets
CAD and design exchange

How to edit .mtl files

Open the file with Blender, make your changes and save.
Most editors preserve the original formatting and encoding — avoid changing the charset.

How to create .mtl files

Create a new file and save it with the .mtl extension, or export this format from Blender.

Frequently asked questions

What programs can open .mtl files?

Common options include Blender, MeshLab, Autodesk Viewer. You can also open many of these files with built-in viewers or a browser.

How do I create a .mtl file?

Create a new file in any text editor or the app that owns the format and save it with the .mtl extension.

What is the relationship between .mtl and the model/mtl MIME type?

model/mtl is the media type identifier used for .mtl files during network transfer (for example in the HTTP Content-Type header).

Sources & standards

Updated 2026-08-18

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