Apple has said that its forthcoming Apple Watch will need to recharge daily, but we're getting a better idea of just how long its battery will last thanks to a report by 9to5Mac's Mark Gurman.
Gurman's sources say the Apple Watch will be powered by an S1 chip that's similar to what Apple uses in current iPod Touch models.
Apple has reportedly targeted the Apple Watch to have 2.5 to 4 hours of active use and around 19 hours of passive use.
That should allow the battery to last 2.5 hours while playing games, but closer 3.5 hours while using standard apps. When used in fitness-tracking mode, it should last about 4 hours.
Left in sleeping mode, the battery should last 2 to 3 days, Gurman reports.
For comparison, Samsung's Gear 2 smartwatch lasts 2 to 3 days with normal use. Motorola's Moto 360 will last about half a day under heavy use, according to Lifehacker UK.
One of the biggest demands on the Apple Watch's battery is its display. Apple has reportedly designed the watch to be able to display a digital clock face for about three hours, though it doesn't expect users will want to do that.
The Apple Watch will turn its display off when its not being used actively or receiving notifications.
Battery life seems to be part of the reason Apple delayed the Apple Watch from late 2014 to early 2015.
We'll have to wait and see if that delay made the watch better for prospective buyers.