Choose a collision detection mode

CollisionA collision occurs when the physics engine detects that the colliders of two GameObjects make contact or overlap, when at least one has a Rigidbody component and is in motion. More info
See in Glossary Detection defines which algorithm the physics body (Rigidbody or ArticulationBody) uses to detect collisions. Different algorithms offer different levels of accuracy, but more accurate algorithms require more computational resources.

There are three algorithms available, represented by four collision detectionAn automatic process performed by Unity which determines whether a moving GameObject with a Rigidbody and collider component has come into contact with any other colliders. More info
See in Glossary modes:

Collision detection mode	Algorithm	Useful for	Not useful for
Discrete	Discrete	- Slow-moving collisions.	- Fast-moving collisions.
Continuous Speculative	Speculative CCD	- Fast-moving collisions.	- Some fast-moving collisions that require an especially high degree of accuracy.
Continuous	Sweep CCD	- Fast-moving linear collisions that require a high degree of accuracy. - Physics bodies that only collide with static colliders.	- Collisions that happen as a result of the physics body rotating. - Physics bodies that collide with moving colliders.
Continuous Dynamic	Sweep CCD	- Fast-moving linear collisions that require a high degree of accuracy. - Physics bodies that collide with moving colliders.	- Collisions that happen as a result of the physics body rotating.

The following decision flow might provide a starting point for selecting a collision detection type. It starts with the least computationally intensive mode, and progresses to the most computationally intensive mode.

Try Discrete first.
If you notice missed collisions in Discrete mode, try Continuous Speculative.
If you notice missed collisions or false collisions in Continuous Speculative mode, try Continuous for collisions with static collidersAn invisible shape that is used to handle physical collisions for an object. A collider doesn’t need to be exactly the same shape as the object’s mesh - a rough approximation is often more efficient and indistinguishable in gameplay. More info
See in Glossary, or Continuous Dynamic for collisions with dynamic RigidbodyA component that allows a GameObject to be affected by simulated gravity and other forces. More info
See in Glossary colliders.

In some cases, you might find that the physics performance relies on a combination of the collision detection mode and the physics timestep frequency. Experiment with both and profile the results to find the right solution for your project.

Select a collision detection mode

To select an algorithm, set the physics body’s Collision Detection property in one of the following ways:

In the Editor: On the Rigidbody or Articulation Body component InspectorA Unity window that displays information about the currently selected GameObject, asset or project settings, allowing you to inspect and edit the values. More info
See in Glossary, change the Collision Detection property.
In code: Use the API properties Rigidbody.collisionDetectionMode and ArticulationBody.collisionDetectionMode.

Collision detection

Discrete collision detection

Unity Manual

Choose a collision detection mode

Select a collision detection mode