Apple Watch Fourth generation (Series 4)

September 21, 2018

The Apple Watch Series 4 is the first prominent redesign of the Apple Watch, featuring larger displays with thinner bezels and rounded corners, and a slightly rounder, thinner chassis with a redesigned ceramic back. Internally there is a new S4 64-bit dual-core processor, capable of up to double the S3's performance, upgraded 16 GB storage, and a new electrical heart sensor. The microphone was moved to the opposite side between the side button and the digital crown to improve call quality. Other changes include the digital crown incorporating haptic feedback with the Apple Haptic Engine and includes the new Apple-designed W3 wireless chip.

The ECG system has received clearance from the United States Food and Drug Administration, a first ever for a consumer device, and is supported by the American Heart Association. The Series 4 can also detect falls, and can automatically contact emergency services unless the user cancels the outgoing call.

The watch received mostly positive reviews from critics. TechRadar gave it a score of 4.5/5, calling it one of the top smartwatches, while criticizing the short battery life. Digital Trends gave it a score of 5/5, calling it Apple's best product and praising the design, build quality, and software, among others, while criticizing the battery life. CNET gave it a score of 8.2/10, calling it the "best overall smartwatch around", while criticizing the battery life and lack of watch face options. T3 gave it a score of 5/5, calling it a "truly next-gen smartwatch" due to its thinner body and bigger screen compared to the Series 3, and health features.

The Apple Series 4 is the first Apple Watch model to add the new Gold stainless steel color option to match the color introduced with the iPhone XS in 2018. It is now available in Space Gray, Silver and Gold aluminum case color options, available in Space Black, Silver and Gold stainless steel case color options. All the ceramic case color options have been removed until the launch of the Apple Watch Edition Series 5 in 2019.

Software support for the Apple Watch Series 4, Series 5, and the first-generation Apple Watch SE ended with watchOS 10.6.1.