Apple Watch SE 3 vs Apple Watch Series 4

Every spec side by side, from each maker's published figures.

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Watch SE 3 compared with Watch Series 4

	AppleWatch SE 3	AppleWatch Series 4
Overview
Released
Released	September 2025	September 2018
Display
Case sizes
Case sizes	40 mm or 44 mm	40 mm or 44 mm
Panel
Panel	LTPO OLED	LTPO OLED
Peak brightness
Peak brightness	1,000 nits	1,000 nits
Always-on display
Always-on display	Yes	No
Display detail
Display detail	Always-On Retina display with OLED and LTPO; 324 x 394 pixels (40mm) or 368 x 448 pixels (44mm) at 326 ppi; 759 or 977 sq mm display area; 2 nits minimum brightness	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)
Screen protection
Screen protection	Ion-X front glass, 4x more crack resistant than SE 2	–
Health and fitness
ECG
ECG	No	Yes
Blood oxygen
Blood oxygen	No	No
Skin temperature
Skin temperature	Yes	No
Sleep apnoea alerts
Sleep apnoea alerts	Yes	No
High blood pressure alerts
High blood pressure alerts	No	No
Body composition
Body composition	No	No
Fall detection
Fall detection	Yes	Yes
Crash detection
Crash detection	Yes	No
GPS
GPS	Single-band	Single-band
Water resistance
Water resistance	50 m	50 m
Sensors
Sensors	Second-generation optical heart sensor; temperature sensor; compass; always-on altimeter; high-g accelerometer; high dynamic range gyroscope; ambient light sensor	Electrical and optical heart sensors; barometric altimeter; accelerometer up to 32 g-forces, improved gyroscope and ambient light sensor
Health features
Health features	Heart Rate app; high and low heart rate notifications; irregular rhythm notifications; sleep apnoea notifications; sleep stages and sleep score; Vitals app (heart rate, respiratory rate, wrist temperature and sleep duration); Cycle Tracking with fertile window and retrospective ovulation estimates, perimenopause and menopause support; Medications; Mindfulness; Noise	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
Fitness features
Fitness features	Custom workouts; Training Load; customisable heart rate zones; VO2 max; Race Route; Pacer; cadence, stride length, ground contact time, vertical oscillation and running power; automatic track detection; multisport workouts; offline maps with custom route creation; Backtrack; pool and open-water swimming with SWOLF; cycling power zones with Bluetooth accessories; GymKit	GPS, GLONASS, Galileo and QZSS; swimming, yoga and hiking workouts, automatic workout reminders, cadence, pace alerts and rolling mile pace in watchOS 5; GymKit
Safety features
Safety features	Emergency SOS; international emergency calling; Fall Detection; Crash Detection; Check In; Backtrack; noise monitoring	Hard-fall detection can call emergency services after immobility and notify emergency contacts; Emergency SOS
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 32 hours	–
Mobile data option
Mobile data option	Yes	Yes
Works with
Works with	iPhone	iPhone
Chip
Chip	S10	S4
Storage
Storage	64 GB (better)	16 GB
Battery life detail
Battery life detail	Up to 18 hours of normal use; up to 32 hours in Low Power Mode; up to 7 hours of outdoor workout	Built-in rechargeable lithium-ion battery
Charging
Charging	Fast charging to 80% in about 45 minutes; 15 minutes for up to 8 hours of normal use; 8 minutes for up to 8 hours of sleep tracking	Magnetic charging cable and USB power adapter
Connectivity
Connectivity	Wi-Fi 4 (802.11n) at 2.4GHz; Bluetooth 5.3; NFC for Apple Pay; L1 GPS (GLONASS, Galileo, QZSS and BeiDou); GPS + Cellular models (A3326, A3328) with 5G RedCap and LTE	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
Design
Weight (lightest version)
Weight (lightest version)	26.3 g (better)	30.1 g
Software
Software	watchOS	watchOS
Case materials
Case materials	100% recycled aluminium case with nylon composite and sapphire crystal back; water resistant to 50 m (ISO 22810:2010)	Aluminium or stainless steel case; ceramic and sapphire crystal back; water resistance under ISO 22810:2010 for shallow-water swimming
Size
Size	40mm is 40 x 34 x 10.7 mm, 26.3 g (GPS) or 26.4 g (GPS + Cellular); 44mm is 44 x 38 x 10.7 mm, 32.9 g (GPS) or 33.0 g (GPS + Cellular)	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
Bands
Bands	Fits 130–200 mm wrists (40mm) or 140–245 mm wrists (44mm)	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
Colours
Colours	Midnight or Starlight aluminium	Silver, Space Grey and Gold aluminium; Silver, Space Black (DLC) and Gold (PVD) stainless steel; Nike+ Silver or Space Grey; Hermès polished stainless steel
In the box
In the box	Apple Watch SE 3, strap, Apple Watch Magnetic Fast Charger to USB-C Cable (1 m)	Watch and band, magnetic charging cable and USB power adapter