Apple Watch Series 4 Models Have Nearly 20% Less Battery Capacity Despite Same 'Up to 18 Hours' Battery Life

Earlier this week, iFixit completed a teardown of an Apple Watch Series 4 that said the 44mm model has roughly four percent more battery capacity, but that was compared to a 38mm-sized Apple Watch Series 3 model.

apple s4
An eagle-eyed MacRumors reader has since pointed us towards Apple's Product Information Sheet, which contains battery capacities measured in watt-hours for several products, including Apple Watch Series 4 models. Apple appears to disclose this information for legal and safety reasons.

Based on Apple's document, Apple Watch Series 4 models actually have less battery capacity than the equivalent Series 3 models:

  • Apple Watch Series 3 (42mm): 1.34 watt-hours

  • Apple Watch Series 4 (44mm): 1.12 watt-hours

  • Apple Watch Series 3 (38mm): 1.07 watt-hours

  • Apple Watch Series 4 (40mm): 0.86 watt-hours

More specifically, the new 44mm Series 4 models have approximately 16.5 percent less battery capacity than the previous large-size 42mm Series 3 models. Likewise, 40mm Series 4 models have approximately 19.7 percent less battery capacity than the previous small-size 38mm Series 3 models.

Despite having smaller batteries, Apple says Series 4 models get the same all-day battery life of up to 18 hours that Series 3 models are rated for. We reached out to Apple in hopes of an explanation, but we have yet to receive a response.

What we do know is that Apple Watch Series 4 models use a new display technology named LTPO that improves power efficiency. The new Apple S4 system-in-a-package also has more efficient cores, so they presumably consume less power as well. Other components could be more efficient too.

In general, however, battery life is simply hard to predict. Different customers have different use cases. One user could be an athlete who is constantly working out with the Apple Watch, while another could be a more casual wearer who taps on a few notifications once in a while and not much else.

All in all, we wanted to clear up some confusion surrounding the Apple Watch Series 4 batteries. They pack less juice, not more, but seemingly without compromising battery life. Over time, we'll see if that's truly the case.

Related Roundup: Apple Watch Series 9
Buyer's Guide: Apple Watch (Caution)

Popular Stories

Apple Intelligence General Feature

Apple Intelligence Features Not Coming to European Union at Launch Due to DMA

Friday June 21, 2024 9:44 am PDT by
Apple today said that European customers will not get access to the Apple Intelligence, iPhone Mirroring, and SharePlay Screen Sharing features that are coming to the iPhone, iPad, and Mac this September due to regulatory issues related to the Digital Markets Act. In a statement to Financial Times, Apple said that there will be a delay as it works to figure out how to make the new...
iOS 18 on iPhone Feature

Everything New in iOS 18 Beta 2

Monday June 24, 2024 12:52 pm PDT by
Apple today released the second betas of iOS 18 and iPadOS 18 to developers, and the software adds support for new features that Apple is working on, plus it tweaks some of the interface changes that have been made in the updates. Apple will refine iOS 18 over the course of the next few months, with multiple changes and refinements expected from now until September. We've highlighted...
Apple WWDC24 Apple Intelligence hero 240610

Apple Explains iPhone 15 Pro Requirement for Apple Intelligence

Wednesday June 19, 2024 4:48 am PDT by
With iOS 18, iPadOS 18, and macOS Sequoia, Apple is introducing a new personalized AI experience called Apple Intelligence that uses on-device, generative large-language models to enhance the user experience across iPhone, iPad, and Mac. These new AI features require Apple's latest iPhone 15 Pro and iPhone 15 Pro Max models to work, while only Macs and iPads with M1 or later chips will...
amazon echo dot

Amazon Could Charge Up to $10/Month for Alexa

Friday June 21, 2024 2:55 pm PDT by
Apple competitor Amazon is working on a revamp of its Alexa assistant, and the new version could cost up to $10 per month, according to a report from Reuters. The upcoming version of Alexa will support conversational generative AI, and Amazon is planning for two tiers of service. There will be a free tier and a second, premium tier that is priced at $5 at a minimum, with Amazon considering...
top stories 22jun2024

Top Stories: Apple Watch X Rumors, New Final Cut App for iPhone, and More

Saturday June 22, 2024 6:00 am PDT by
The avalanche of news coming out of WWDC earlier this month is finally starting to slow, but that doesn't mean there wasn't still lots to talk about in Apple news and rumors this week. This week saw some additional rumors about the upcoming Apple Watch models, the release of major Final Cut Pro updates, the launch of Apple's annual Back to School promo in the U.S. and Canada, new...

Top Rated Comments

benshive Avatar
75 months ago
They improved energy efficiency and were able to shrink the battery a bit in order to make the watch thinner while maintaining the same battery life is what I suspect. My Series 4 easily lasts all day.
Score: 32 Votes (Like | Disagree)
SVTmaniac Avatar
75 months ago
I’ll be the first, why not keep the same size battery and increase the usage time even more? Never makes sense to me.
Score: 29 Votes (Like | Disagree)
MrGimper Avatar
75 months ago
To be honest, I'm sure people would have preferred a slightly larger battery vs the 1mm reduction in thickness.
Score: 27 Votes (Like | Disagree)
powaking Avatar
75 months ago
Um 18 hours? I just wore my watch for 23 hours (and yes that includes using Sleep++ to track my sleeping) and my watch still had 65% battery left. I've been wearing my watch since 7 eastern and right now I have 88% left. I don't see why anyone couldn't get through a day easily with the series 4.
Score: 18 Votes (Like | Disagree)
OldSchoolMacGuy Avatar
75 months ago
Not hard to figure out. More efficient processor means same battery life even with a slightly smaller battery.
Score: 16 Votes (Like | Disagree)
Graphikos Avatar
75 months ago
To be honest, I'm sure people would have preferred a slightly larger battery vs the 1mm reduction in thickness.
I guess speak for yourself. The battery life for my S4 LTE 44mm so far has been perfectly adequate. It's 2 pm and I'm still at 93%. My S0 would be dead in about 4 hours from now, but it's old so hardly worth comparing against.

For me, I'll take a smaller package with this kind of battery life.
Score: 12 Votes (Like | Disagree)