It is whatever the length is in your target publisher's guidelines. Most websites will have those up.
And keep in mind this bit of agent-info from February of this year:
http://pubrants.blogspot.com/2006/02/state-of-chick-lit-nation.html
There are still chick lit titles on the racks, but they were bought 1-2 years ago and the houses want to get their money out of them.
Not trying to discourage, but you may want to reconsider the current label before submitting to a house or agent. They are sensitive to trends--especially ones considered to be over. I'm not sure what alternative, perhaps "contemporary /or humorous women's fiction" might do.
One tip is to aim the book at the editor/agent of any recent-release book that shares themes similar to your work. (Keeping in mind how long ago that book was sold.)
Good luck!