Please be specific in what you are asking, as you can see there are different answers dependent on the exact information you are looking for. Are you looking for how long your battery is expected to last in general over the life of the phone? Looking for information on how long the up time is expected to be for the current charge cycle?
If you are looking for how long your battery is expected to last during the expected life expectancy of the phone, the answer would be that under normal circumstances and barring a defect in the battery or any abuse, the battery should last for the expected life cycle of the phone. If you are asking about the current charge cycle, you can go to settings/battery and there is a graphic that will tell you (after it learns your usage patterns) how many hours you can be expected to get out of the current charge. For normal usage, you should get between 18-20 hours with no power saving measures taken. More if you enable certain power saving settings.
