How long does a fully charged iPhone 3 last?

Answer 1

Depends how old the iPhone is. For some, it's 8 hours average. For other's, it may be only 10 hours standby time and only 4 hours gaming time because its a really used one.

However... Apple boasted that:

"...the 3GS can last for up to ten hours of video, nine hours of web browsing on Wi-Fi, twelve hours of 2G talk time, or five on 3G, 30 hours of music, or 300 hours of standby."

Whatever the case, the iPhone 3GS is powered by an internal 3.7 V 1219 mAh rechargeable lithium-ion polymer battery.

Answer 2

full charge:

Usage: 6 hrs 50 mins

Standby: 1 day 19 hrs

full charge:

Usage: 7 hrs 08 mins

Standby: 1 day 15 hrs

full charge:

Usage:4hrs

Stanby:2days 25mins

It really depends on how much and how long you use it and it if has energy saving settings or not.