Why does my base64 encoded SHA-1 hash contain 56 c

Question

Maybe a completely stupid question but I just cannot work it out...

First I need to generate an SHA-1 hash using part of my submission markup. The hash is correct and the output is;

0623f7917a1e2e09e7bcc700482392fba620e6a2

Next I need to base64 encode this hash to a 28 character sting. This is where I am struggling as when I run my code (or use the online generators) I get a 56 character sting. The sting I get is;

MDYyM2Y3OTE3YTFlMmUwOWU3YmNjNzAwNDgyMzkyZmJhNjIwZTZhMg==

Question is 1) Is it possible to get a 28 char string from the hash above? and 2) how... where could I be going wrong.

Thank you for any help provided.