How long does an iPhone 4 battery last?

I'm taking a road trip, and I was trying to figure out how long my batter will last. I've never really tracked it down. I remember seeing a website that showed like how many hours you could listen music, or talk on the phone, or text. I tried finding the info again but can't find it.

6-7 hours, I believe.

It depends on the age of the phone and a bunch of other factors like temperature, humidity, etc. However on average an IPhone battery should last about:
This is from

iPhone 5 offers up to 8 hours of talk time on 3G, 8 hours of Internet use on 3G, 10 hours of Internet use on Wi-Fi, 10 hours of video playback, or 40 hours of audio playback on a full charge at original capacity. In addition, iPhone 5 features up to 225 hours of standby time.

I'm not exactly sure how that converts to an iphone 4, I think it should be about the same,