What is the average algorithmic complexity of reading from a hash table?

The average algorithmic complexity of reading from a hash table is usually considered O(1) — that is, constant. This is achieved through direct access to the element via the hash code of the key.

However, in the worst case, due to collisions or poor distribution of the hash function, the complexity can degrade to O(n), where n is the number of elements in the table. In real-world conditions, with good hashing and maintaining a low load factor, read operations remain very fast.