How do you check if password needs re-hash?

[nicgene]

Is there any way to check if the hash implements the algorithm?

I've done it in other languages. https://www.php.net/manual/en/function.password-needs-rehash.php

[Uzlopak]

The only case I can think of is, when you increase the saltrounds, that you check if the given hash is lower than the desired hash. If so, rehash with more rounds and same salt...