For all of the information that Apple disclosed regarding Apple Watch last September, the company – outside of saying the device needs to be charged nightly – failed to delve into exactly what sort of battery life one can expect from its first wearable.

Sources familiar with the matter have since disclosed that information – and more – to 9to5Mac.

The publication reports that the first generation Apple Watch will be powered by an Apple S1 chip with a similar performance output to the company’s A5 chip found in the current-generation iPod touch. It’ll run a stripped-down version of iOS codenamed SkiHill that’ll push content out to a Retina-class display capable of refreshing at 60 frames per second.

As of now, Apple is said to be targeting 2.5 hours of heavy application use like processor-intensive games and 3.5 hours of standard app use. That figure climbs to four hours when using built-in fitness tracking software, sources said.

Mixed usage battery life is targeted at 19 hours and in stand-by or low-power modes, Apple anticipates users will get 2-3 days of use on a single charge.

Battery life has been a concern for Apple over the past year and was one of the reasons the launch date was pushed back from late 2014 to early 2015. Postponing the release has given them extra time to test the watch in the real world with nearly 3,000 units reportedly already out in the wild.

All signs suggest Apple is still on track to launch the wearable by the end of March.