Compare IDisposable and finalizers in .NET. When would you use each?

When do you use IDisposable instead of a finalizer in .NET?

Distinguishes deterministic cleanup from finalization and explains resource ownership in normal application code.

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IDisposable is for deterministic cleanup of resources when the owner is done with them. A finalizer runs later on the GC finalizer path and is mostly a safety net for types that directly own unmanaged resources. In normal application code, I prefer using statements, await using when needed, and clear ownership rules. I would not add a finalizer just because a class uses memory; memory is already handled by the GC.

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Resource cleanup, deterministic disposal, finalization cost, ownership boundaries, and safe cleanup habits.

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Why this question matters
Disposal defines deterministic ownership of sockets, streams, handles, timers, connections, and other resources that GC cannot release promptly. Finalization is a delayed safety net for low-level unmanaged ownership, not routine application cleanup.
IDisposable is for deterministic cleanup of resources when the owner is done with them. A finalizer runs later on the GC finalizer path and is mostly a safety net for types that directly own unmanaged resources. In normal application code, I prefer using statements, await using when needed, and clear ownership rules. I would not add a finalizer just because a class uses memory; memory is already handled by the GC.
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The key difference is timing and responsibility. Dispose gives the application an explicit cleanup point, which is important for file handles, streams, database connections, timers, and native handles. Finalizers are nondeterministic and add GC cost because finalizable objects need extra processing before memory can be reclaimed. Most business classes do not need finalizers. If I wrap an unmanaged handle directly, I would usually rely on SafeHandle and implement the dispose pattern carefully rather than inventing custom cleanup logic everywhere.

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Adding finalizers to ordinary classes without unmanaged ownership.
Forgetting to dispose streams, timers, or subscriptions.
Disposing dependencies that are owned by the DI container.
Confusing memory cleanup with resource cleanup.

Compare IDisposable and finalizers in .NET. When would you use each?

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