Unity Physics Body Types

Source: Dev.to

Static Bodies

Static bodies are completely immobile. Once placed in the scene, they stay fixed in position and rotation. They don’t respond to forces or collisions, but other objects can collide with them.

Key Characteristics

• No Rigidbody required in 3D (collider alone is enough)
• Use Rigidbody2D with bodyType = Static in 2D
• Optimised for performance; Unity doesn’t have to recalculate their position

Ideal for

• Walls, floors, terrain, or background structures

Kinematic Bodies

Kinematic bodies don’t respond to physics forces or collisions themselves, but they can still affect Dynamic bodies if they move into them. They’re moved through scripting (e.g., by changing transform.position or setting velocity).

Key Characteristics

• Set isKinematic = true on Rigidbody (3D) or bodyType = Kinematic on Rigidbody2D (2D)
• Not affected by gravity or collisions

Useful for

• Elevators, doors, conveyor belts, or moving platforms

Dynamic Bodies

Dynamic bodies are fully simulated by the physics engine. They respond to gravity, forces, collisions, and other physical interactions. These are the most “alive” objects in your scene.

Key Characteristics

• Requires Rigidbody (3D) or Rigidbody2D (2D)
• Use bodyType = Dynamic for 2D
• Reacts to AddForce, velocity, mass, and friction

Ideal for

• Players, enemies, falling crates, or any object that moves physically

Choosing the Right Type

• Static – use for anything that never moves.
• Dynamic – use when you want full physics interaction.
• Kinematic – use when you need scripted or manual movement without physics influence.