Apple promised improved battery life for its new iPhone 5s and 5c, but other than endurance times for a few use cases, the company gave little info on the battery itself. Luckily, it's FCC's job to certify such aspects of a mobile device so now we have the actual battery capacity.
The iPhone 5, 5s and 5c batteries all work at 3.8V, but differ in battery size. The iPhone 5 had a 5.45Wh battery which works out to 1,440mAh. The iPhone 5c (http://www.gsmarena.com/apple_iphone_5c-5690.php) has a bigger, 5.73Wh battery or 1,507mAh and the iPhone 5s (http://www.gsmarena.com/apple_iphone_5s-5685.php) has the biggest battery of the three at 5.96Wh or 1,570mAh.
V Wh mAh [/tr] [tr]
iPhone 5 [td]3.8[/td] [td]5.45[/td] [td]1,440[/td] [/tr] [tr]
iPhone 5c [td]3.8[/td] [td]5.73[/td] [td]1,507[/td] [/tr] [tr]
iPhone 5s [td]3.8[/td] [td]5.96[/td] [td]1,570[/td] [/tr] [/table] It's interesting that the iPhone 5s battery grew more, even though the phone is as thin as the iPhone 5, while the 5c is thicker.
Source 1 (https://apps.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout=500&calledFromFrame=N&application_id=676707&fcc_id=BCG-E2642A)