Apple Watch SE 3 — Overview & Key Description

The SE 3 is Apple’s refreshed entry-level smartwatch for 2025. It brings in several features that were previously reserved for the “premium” lines, while still aiming for a more accessible price point. The idea is to get many of the modern essentials (health, fitness, connectivity) in a lighter / simpler package.

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Key Features & Specs

Here are its main features and specifications:

Category    Details

Cases / Colors / Sizes    Aluminum case. Available in two finishes: Midnight and Starlight.  <br>Two sizes: 40 mm and 44 mm. 
Display    Always-On Retina display using OLED LTPO.  <br>Peak brightness: up to ~1,000 nits.  <br>Covers “Ion-X” front glass with improved durability: 4× more crack-resistance vs previous generation. 
Processor / Storage    Uses the S10 chip (64-bit dual-core, plus 4-core Neural Engine).  <br>Storage: 64 GB. 
Sensors & Health / Wellness    • Second-generation optical heart sensor (heart rate, high/low & irregular rhythm notifications).  <br>• Temperature sensor (used for e.g. retrospective ovulation estimates etc.).  <br>• Compass, always-on altimeter, high-g accelerometer, HDR gyroscope, ambient light sensor.  <br>• Sleep app with sleep stages, Sleep Score, sleep apnea notifications.  <br>• Cycle Tracking with retrospective ovulation estimate. 
Connectivity / Network    • GPS only version + GPS + Cellular version.  <br>• Supports 5G cellular on cellular models.  <br>• WiFi (802.11n), Bluetooth 5.3. 
Controls & Gestures    • Digital Crown with haptic feedback, Side button.  <br>• New gestures: “double-tap” (thumb + index finger) and wrist-flick to dismiss alerts / snooze / answer calls etc. 
Audio / Speaker / Media    • Speaker and microphone. <br>• For the first time (in SE line), support for playing media (music / podcasts) directly through the speaker. 
Battery Life & Charging    • “All-day battery life” of up to 18 hours under normal usage.  <br>• In Low Power Mode: up to ~32 hours.  <br>• Fast-charging: 15 minutes charging gives ~8 hours of normal use. Up to ~80% in ~45 minutes.  <br>• Also short charge (~8 min) gives ~8 hours of sleep tracking. 
Durability & Water Resistance    Water resistance to 50 meters (suitable for swimming etc.). 
Other Safety / Features    • Fall detection, Emergency SOS, Crash Detection etc.  <br>• On-device Siri, with more local processing. 

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Things Not Included / Limits Compared to Premium Models

SE 3 does not have an ECG sensor. 

It does not have a blood-oxygen (SpO₂) sensor. 

The display is not as rugged or bright in every scenario as Ultra etc., though the improvements are significant.

Some advanced health sensors in Series/Ultra models are missing.