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Apple Watch SE 3 vs Apple Watch Series 12

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

Better figure, where one is clearly better

AppleWatch SE 3AppleWatch Series 12
Overview
ReleasedSeptember 2025September 2026
Display
Case sizes40 mm or 44 mm42 mm or 46 mm
PanelLTPO OLEDLTPO OLED
Peak brightness1,000 nits2,000 nits
Always-on displayYesYes
Display detailAlways-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 brightnessAlways-On Retina display with wide-angle OLEDs and LTPO3; 1Hz refresh; 374 x 446 pixels (42mm) or 416 x 496 pixels (46mm) at 326 ppi; 970 or 1,196 sq mm display area; 1 nit minimum brightness
Screen protectionIon-X front glass, 4x more crack resistant than SE 2Ceramic Shield 2 (aluminium cases); sapphire front crystal (titanium and ceramic cases)
Health and fitness
ECGNoYes
Blood oxygenNoYes
Skin temperatureYesYes
Sleep apnoea alertsYesYes
High blood pressure alertsNoYes
Body compositionNoNo
Fall detectionYesYes
Crash detectionYesYes
GPSSingle-bandSingle-band
Water resistance50 m50 m
SensorsSecond-generation optical heart sensor; temperature sensor; compass; always-on altimeter; high-g accelerometer; high dynamic range gyroscope; ambient light sensorHealth Sensing System with third-generation electrical heart sensor, always-on optical heart sensor, blood oxygen sensor and temperature sensor; compass; always-on altimeter; high-g accelerometer; high dynamic range gyroscope; ambient light sensor; depth gauge to 6 m; water temperature sensor
Health featuresHeart 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; NoiseReadiness app; Vitals app (heart rate, respiratory rate, wrist temperature, blood oxygen, sleep duration and HRV); Recovery HRV; high-frequency background heart rate tracking; ECG app; Blood Oxygen app; irregular rhythm notifications; high and low heart rate notifications; hypertension notifications; sleep apnoea notifications; sleep stages and sleep score; Cycle Tracking with fertile window and retrospective ovulation estimates, perimenopause and menopause support; Medications; Mindfulness; Noise
Fitness featuresCustom 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; GymKitCustom 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
Safety featuresEmergency SOS; international emergency calling; Fall Detection; Crash Detection; Check In; Backtrack; noise monitoringEmergency SOS; international emergency calling; Fall Detection; Crash Detection; Check In; Backtrack; Last Emergency Call Availability Waypoint; torch; noise monitoring
Battery and connections
Battery life (maker's claim)Up to 18 hoursUp to 24 hours
In low-power modeUp to 32 hoursUp to 38 hours
Mobile data optionYesYes
Works withiPhoneiPhone
ChipS10S11
Storage64 GB64 GB
Battery life detailUp to 18 hours of normal use; up to 32 hours in Low Power Mode; up to 7 hours of outdoor workoutUp to 24 hours of normal use; up to 38 hours in Low Power Mode; up to 10 hours of outdoor workout
ChargingFast 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 trackingFast charging to 80% in about 30 minutes; 15 minutes for up to 12 hours of normal use; 5 minutes for up to 10 hours of sleep tracking
ConnectivityWi-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 LTEWi-Fi 4 (802.11n) at 2.4GHz and 5GHz; Bluetooth 5.3; second-generation Ultra Wideband chip; NFC for Apple Pay; Precision L1 GPS (GPS, GLONASS, Galileo, QZSS and BeiDou); GPS + Cellular models (A3582, A3587) with 5G RedCap and LTE
Design
Weight (lightest version)26.3 g31.5 g
SoftwarewatchOSwatchOS
Case materials100% recycled aluminium case with nylon composite and sapphire crystal back; water resistant to 50 m (ISO 22810:2010)100% recycled aluminium or 3D-printed 100% recycled titanium case with zirconia back, or ceramic case; water resistant to 50 m (ISO 22810:2010); IP6X dust resistant
Size40mm 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)42mm is 42 x 37 x 9.7 mm (ceramic 43 x 37 x 9.85 mm); 46mm is 46 x 40 x 9.7 mm (ceramic 47 x 41 x 9.85 mm); lightest is the 42mm aluminium GPS + Cellular at 31.5 g, heaviest the 46mm Night Blue ceramic at 52.9 g
BandsFits 130–200 mm wrists (40mm) or 140–245 mm wrists (44mm)Fits 130–200 mm wrists (42mm) or 140–245 mm wrists (46mm)
ColoursMidnight or Starlight aluminiumAluminium in Dark Bronze, Light Gold, Black and Space Grey; titanium in Radiant Gold and Natural; ceramic in Pearl White and Night Blue
In the boxApple Watch SE 3, strap, Apple Watch Magnetic Fast Charger to USB-C Cable (1 m)Apple Watch Series 12, strap, Apple Watch Magnetic Fast Charger to USB-C Cable (1 m)

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