URDF VS SDF

Robot model or simulation world? Start with the responsibility.

URDF is deeply embedded in ROS robot-model workflows. SDFormat extends further into simulation-oriented models, sensors, physics and complete worlds.

MATURITYREFERENCE COMPARISON

LAST VERIFIED22 Sep 2026

SOURCE VERSIONROS URDF + current SDFormat documentation

EVIDENCE BOUNDARYResponsibility comparison for developer choice; conversion may be lossy and no universal winner is asserted.

DECISION MATRIX

Compare the responsibilities before comparing syntax.

DIMENSIONURDFSDF

Primary focus

Robot model structure in ROS-oriented workflows.

Simulation-oriented models and complete worlds.

Structure

Links connected by joints.

Models containing links and joints, plus world-level composition.

Environment

Not a full world-description format.

Worlds, scene configuration, lights and physics are first-class.

Sensors

Commonly handled through ecosystem extensions and adjacent configuration.

Broad simulation sensor declarations are part of the format.

Physics

Selected physical properties and dynamics.

Simulation physics and surface properties are core concerns.

ROS ecosystem

Native center of gravity.

Often used with Gazebo/simulation ecosystems and ROS bridges.

Conversion

Useful upstream robot source for many workflows.

Can preserve simulation context that does not fit back into URDF.

CHOOSE URDF

CHOOSE SDF

You need one description that includes robots and the surrounding simulation world.
Sensors, lights, physics and environment settings are part of the artifact.
Gazebo-oriented simulation behavior is a primary use case.
The model must express concepts that do not round-trip cleanly through URDF.

USE BOTH

Maintain URDF as the ROS-facing robot model while generating or maintaining SDF for richer simulation.

Treat conversion as lossy when the target format cannot represent source-specific concepts.

Keep semantic embodiment or provenance in a separate layer rather than forcing either format to own it.

PRIMARY SOURCES