Apple Watch SE 3 vs Apple Watch Series 9

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

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Watch SE 3 compared with Watch Series 9

	AppleWatch SE 3	AppleWatch Series 9
Overview
Released
Released	September 2025	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	Yes	Yes
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	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, 4x more crack resistant than SE 2	Ion-X front glass (aluminium cases); sapphire front crystal (stainless steel cases)
Health and fitness
ECG
ECG	No	Yes
Blood oxygen
Blood oxygen	No	Yes
Skin temperature
Skin temperature	Yes	Yes
Sleep apnoea alerts
Sleep apnoea alerts	Yes	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	Yes	Yes
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 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	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 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	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	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	Emergency SOS; international emergency calling; Fall Detection; Crash Detection; Check In; Backtrack; noise monitoring	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 32 hours	Up to 36 hours
Mobile data option
Mobile data option	Yes	Yes
Works with
Works with	iPhone	iPhone
Chip
Chip	S10	S9
Storage
Storage	64 GB	64 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	Fast charging to 80% in about 45 minutes
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	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)	26.3 g (better)	31.9 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; water resistant to 50 m (swimproof); IP6X dust resistant
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)	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	Fits 130–200 mm wrists (40mm) or 140–245 mm wrists (44mm)	Fits 130–200 mm wrists (41mm) or 140–245 mm wrists (45mm)
Colours
Colours	Midnight or Starlight aluminium	Aluminium in Pink, Midnight, Starlight, Silver and (PRODUCT)RED; stainless steel in Gold, Silver and Graphite
In the box
In the box	Apple Watch SE 3, strap, Apple Watch Magnetic Fast Charger to USB-C Cable (1 m)	Apple Watch Series 9, strap, Apple Watch Magnetic Fast Charger to USB-C Cable (1 m)