Apple Watch Series 4 vs Apple Watch Series 9

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Watch Series 4 compared with Watch Series 9

	AppleWatch Series 4	AppleWatch Series 9
Overview
Released
Released	September 2018	September 2023
Display
Case sizes
Case sizes	40 mm or 44 mm	41 mm or 45 mm
Panel
Panel	LTPO OLED	LTPO OLED
Peak brightness
Peak brightness	1,000 nits	2,000 nits (better)
Always-on display
Always-on display	No	Yes
Display detail
Display detail	Retina LTPO OLED with Force Touch; 40mm 324 x 394 pixels and 759 sq mm; 44mm 368 x 448 pixels and 977 sq mm; display wakes by wrist raise (PhoneArena)	Always-On Retina LTPO OLED display, edge to edge; 326 ppi; up to 2,000 nits maximum and 1 nit minimum brightness
Screen protection
Screen protection	–	Ion-X front glass (aluminium cases); sapphire front crystal (stainless steel cases)
Health and fitness
ECG
ECG	Yes	Yes
Blood oxygen
Blood oxygen	No	Yes
Skin temperature
Skin temperature	No	Yes
Sleep apnoea alerts
Sleep apnoea alerts	No	Yes
High blood pressure alerts
High blood pressure alerts	No	Yes
Body composition
Body composition	No	No
Fall detection
Fall detection	Yes	Yes
Crash detection
Crash detection	No	Yes
GPS
GPS	Single-band	Single-band
Water resistance
Water resistance	50 m	50 m
Sensors
Sensors	Electrical and optical heart sensors; barometric altimeter; accelerometer up to 32 g-forces, improved gyroscope and ambient light sensor	Electrical heart sensor; third-generation optical heart sensor; temperature sensing; compass; always-on altimeter; high-g accelerometer; high dynamic range gyroscope; ambient light sensor
Health features
Health features	ECG capability, high and low heart-rate alerts and irregular-rhythm notifications; ECG app was not available at hardware launch and reached the UK in March 2019	ECG app; Blood Oxygen app; sleep apnoea notifications and hypertension notifications (added in later watchOS updates); irregular rhythm notifications; high and low heart rate notifications; sleep stages; Cycle Tracking with retrospective ovulation estimates; Medications; Mindfulness; Noise
Fitness features
Fitness features	GPS, GLONASS, Galileo and QZSS; swimming, yoga and hiking workouts, automatic workout reminders, cadence, pace alerts and rolling mile pace in watchOS 5; GymKit	Custom interval workouts; Heart Rate Zones; Race Route; stride length, ground contact time and vertical oscillation; automatic track detection; multisport workouts; Backtrack; pool and open-water swimming with SWOLF and automatic stroke detection; cycling Functional Threshold Power, power zones and cadence with Bluetooth accessories; GymKit
Safety features
Safety features	Hard-fall detection can call emergency services after immobility and notify emergency contacts; Emergency SOS	Emergency SOS; international emergency calling; Crash Detection; Fall Detection
Battery and connections
Battery life (maker's claim)
Battery life (maker's claim)	Up to 18 hours	Up to 18 hours
In low-power mode
In low-power mode	–	Up to 36 hours
Mobile data option
Mobile data option	Yes	Yes
Works with
Works with	iPhone	iPhone
Chip
Chip	S4	S9
Storage
Storage	16 GB	64 GB (better)
Battery life detail
Battery life detail	Built-in rechargeable lithium-ion battery	Built-in rechargeable lithium-ion battery
Charging
Charging	Magnetic charging cable and USB power adapter	Fast charging to 80% in about 45 minutes
Connectivity
Connectivity	W3 wireless chip; Wi-Fi 802.11b/g/n at 2.4GHz; Bluetooth 5.0; cellular versions add LTE and UMTS with a compatible plan; GPS requires iPhone 5s, cellular iPhone 6, both with iOS 12 at launch	L1 GPS, GNSS, Galileo and BeiDou; 4G LTE and UMTS (GPS + Cellular models); Wi-Fi 4 (802.11n); Bluetooth 5.3; second-generation Ultra Wideband chip with Precision Finding for iPhone 15 and later; Apple Pay
Design
Weight (lightest version)
Weight (lightest version)	30.1 g (better)	31.9 g
Software
Software	watchOS	watchOS
Case materials
Case materials	Aluminium or stainless steel case; ceramic and sapphire crystal back; water resistance under ISO 22810:2010 for shallow-water swimming	Aluminium or stainless steel case; water resistant to 50 m (swimproof); IP6X dust resistant
Size
Size	40mm 40 x 34 x 10.7 mm, 30.1 g aluminium or 39.8 g steel; 44mm 44 x 38 x 10.7 mm, 36.7 g aluminium or 47.9 g steel; weights exclude bands	41mm is 41 x 35 x 10.7 mm, 31.9 g (aluminium, GPS), 32.1 g (aluminium, GPS + Cellular) or 42.3 g (stainless steel); 45mm is 45 x 38 x 10.7 mm, 38.7 g (aluminium, GPS), 39.0 g (aluminium, GPS + Cellular) or 51.5 g (stainless steel); lightest is the 41mm aluminium GPS
Bands
Bands	Compatible with earlier Apple Watch bands of the corresponding size; Nike+ includes Nike bands and watch faces; Hermès includes leather bands and exclusive faces. Nike+ became available 5 October 2018	Fits 130–200 mm wrists (41mm) or 140–245 mm wrists (45mm)
Colours
Colours	Silver, Space Grey and Gold aluminium; Silver, Space Black (DLC) and Gold (PVD) stainless steel; Nike+ Silver or Space Grey; Hermès polished stainless steel	Aluminium in Pink, Midnight, Starlight, Silver and (PRODUCT)RED; stainless steel in Gold, Silver and Graphite
In the box
In the box	Watch and band, magnetic charging cable and USB power adapter	Apple Watch Series 9, strap, Apple Watch Magnetic Fast Charger to USB-C Cable (1 m)