This question already has an answer here:
Are all or any hash functions evenly distributed?
For example: if you had every combination of 256 bits and ran that through SHA256, would that produce approximately 1 of each combination, or would there be peaks?
Are distributions of the hashes calculable without going through the permutations in lower bit sizes?
Is evenness of the distribution of a hash function impacted by the length of the input vs the resultant hash length?
Which hashing functions are most evenly distributed? (e.g. as close to 1 of each equal-bit-length combination possible)
Edit: The linked "duplicate" doesn't come close to addressing all these questions.