How big can a user agent string get?

Question

If you were going to store a user agent in a database, how large would you accomdate for?

I found this technet article which recommends keeping UA under 200. It does

Answer 1

HTTP specification does not limit length of headers at all. However web-servers do limit header size they accept, throwing 413 Entity Too Large if it exceeds.

Depending on web-server and their settings these limits vary from 4KB to 64KB (total for all headers).