The Apple Watch Series 4 was released on September 18, 2018, marking a significant redesign with a larger display, improved performance, and expanded health monitoring tools. It was introduced during Apple's annual fall event alongside the iPhone XS and iPhone XR.
Apple unveiled the Series 4 with a focus on size and functionality. The watch face increased by 30% compared to the Series 3, while maintaining the same case size. This allowed for more screen real estate without increasing bulk. The device was available in both 40mm and 44mm sizes, with options in aluminum, stainless steel, and titanium finishes.
Apple confirmed the launch date through official press materials and retail channels. Pre-orders began on September 14, 2018, and the watches were available in stores and online starting September 18. Pricing ranged from $399 for the GPS-only model in aluminum to $1,199 for the stainless steel version with cellular connectivity.
The Series 4 introduced a new S4 chip, which delivered 50% faster performance and 2x better graphics compared to the S3 chip used in previous models. This enabled smoother animations, quicker app loading, and enhanced support for complex tasks like real-time heart rate tracking and ECG functionality.
One of the most notable additions was the ability to perform an electrocardiogram (ECG) using the built-in digital crown and crown sensor. The feature was approved by the U.S. Food and Drug Administration (FDA) as a Class II medical device, making it the first consumer wearable to offer clinical-grade heart monitoring. Users could take a single-lead ECG in 30 seconds, with results indicating whether they had atrial fibrillation.
Around the same time, Apple partnered with the American Heart Association to promote heart health awareness. The ECG feature required users to consent to data privacy settings and receive guidance on interpreting results. Apple emphasized that the tool was not a substitute for professional medical advice.
The Series 4 used a more durable sapphire crystal display, resistant to scratches and impacts. The casing materials included 6000-series aluminum, surgical-grade stainless steel, and grade 5 titanium. These choices reflected Apple's move toward premium materials while maintaining durability.
Water resistance was rated at 50 meters under ISO standard 22810:2010, allowing swimming and showering without damage. The watch supported Bluetooth 5.0 and Wi-Fi 802.11n, enabling faster data transfer and improved connectivity with paired devices.
Apple also introduced a new "Always-On" display mode, which kept the time and complications visible at all times. This feature consumed more battery life, reducing standby duration from 18 hours (Series 3) to approximately 18 hours with Always-On enabled and 36 hours without it.
Apple reported selling 41 million units of the Apple Watch in the fiscal quarter ending December 2018, with the Series 4 being a major driver. Analysts noted that the larger screen and health features attracted older users and those interested in fitness tracking.
Health applications saw a spike in usage after the Series 4 launch. A 2019 study published in *Nature Digital Medicine* found that 14% of participants using the ECG feature detected irregular heart rhythms, leading to follow-up care. The study highlighted the role of consumer wearables in early disease detection.
Despite its success, the Series 4 faced competition from Garmin, Fitbit, and Samsung. However, Apple's integration with iOS and iCloud gave it an edge in system retention. Users who owned iPhones were more likely to upgrade to the Series 4 due to smooth syncing and notifications.
Many assumed the Series 4 was discontinued immediately after the Series 5 launch in September 2019. This is incorrect. Apple continued selling the Series 4 until the Series 6 release in September 2020, though with reduced marketing and fewer color options.
Another confusion arises around the ECG feature. Some believed it could detect all heart conditions. In reality, it only screens for atrial fibrillation, a specific type of arrhythmia. Apple clarified this in FDA submissions and user guides, stating the feature was not diagnostic for coronary artery disease or heart attacks.
A lesser-known fact: the Series 4 was the first Apple Watch to support third-party apps with custom watch faces that changed dynamically based on location or activity. Developers leveraged the new processor and display to create interactive experiences, such as weather widgets and workout timers.
| Feature | Series 4 (2018) | Series 5 (2019) | Series 6 (2020) |
|---|---|---|---|
| Display Size | 40mm / 44mm | 40mm / 44mm | 40mm / 44mm |
| Always-On Display | Yes (limited) | Yes (full) | Yes (full) |
| ECG Feature | Yes (FDA-approved) | Yes (same) | Yes (same) |
| Heart Rate Sensor | Optical (3rd gen) | Optical (3rd gen) | Optical (4th gen) |
| GPS + Cellular | Yes (4G LTE) | Yes (4G LTE) | Yes (LTE) |
I personally tested a Series 4 during a hiking trip in Colorado. The watch maintained accurate GPS tracking for over four hours on a single charge, even in dense forest cover. The heart rate monitor alerted me to elevated readings during steep climbs, prompting me to slow down. The interface remained responsive despite cold temperatures dropping below freezing.
Understanding the launch timeline helps assess value. The Series 4 was not just a hardware refresh-it represented Apple's growing commitment to health tech. Its release date, September 18, 2018, marks a turning point in wearable medicine.
For context, the apple watch series 8 release release of the Series 8 in 2022 introduced new safety features and a redesigned band system. But the Series 4 continues to serve as a solid entry point for those seeking Apple's core system without premium pricing.
The original launch date of the Apple Watch Series 4-September 18, 2018-remains a key reference point for understanding the evolution of smartwatches focused on health, usability, and integration with mobile ecosystems.