NSB SQL Database Size Allocation

I’ve been asked for the NSB (SQL Transport) recommended database allocation size when starting an integration.
I have known in the past integration that the database is not of great size, but I’d like to know in size terms/numbers, what is recommended when setting a new nsb database.
Thanks in advance.

It really depends on your message size and volume. I would suggest setting up a test environment and testing with real production-like data.
If you enable AutoGrowth on the SQL database then it will take care of the problem for you.