Code inspection: Redundant capacity argument

This inspection reports a capacity argument whose value is smaller than the number of elements already provided for a List<T>. In this case, the list will have to grow while the initializer or collection expression is evaluated, so the specified initial capacity is not useful.

The inspection applies to new List<T>(capacity) { ... } initializers and to C# collection expressions that use with(capacity: ...).

Example

                using System.Collections.Generic;
                var numbers = new List<int>(capacity: 2) { 1, 2, 3 };
            

                using System.Collections.Generic;
                var numbers = new List<int>(capacity: 3) { 1, 2, 3 };
            

Collection expression example

                using System.Collections.Generic;
                List<int> numbers = [with(capacity: 2), 1, 2, 3];
            

                using System.Collections.Generic;
                List<int> numbers = [with(capacity: 3), 1, 2, 3];
            

Quick-fix

Update the capacity to the number of provided elements. For collection expressions, the quick-fix can also remove the with(...) element if the explicit capacity is not needed.

19 June 2026