wifi turn off when sleep

[ItsMyDesire]

How do I set the policy to switch WiFi off after say 15 minutes of inactivity?

 

[Unfriendly]

wi-fi settings > menu > advanced > wi-fi sleep policy

 

[Banzibarn]

Thanks for this, I didn't know this option was there.

I presume the the "never when plugged in" option will default to 15 minutes if not plugged in?