I got this from a book and thought it might help.

"Why fragrance knock-offs and inexpensive imitations just don't work:

Eau de cologne(about 3% to 5%fragrance)lasting 2 to 3 hours;eau de toilette(5% to 7%fragrance) lasting 2 to 4 hours; eau de parfum(12%to18% fragrance)lasting 4 to 6 hours; and perfume(15% to 30%fragrance) lasting 6 to 8 hours or more. Perfume is more expensive, but it does have a better potenial for lasting the whole day because the oil and fagrance concentration cling better to skin, so it tends not to wear off as easily as alcohol-and water-based fragances."

I hope this helps!