Detailed Technical Specifications

Product Information

• Product Name: Apple Watch Series 4
• Model: GPS + Cellular, 40mm
• Brand: Apple
• Series: Series 4 (4th Generation)
• Category: Smartwatch
• Case Material: Aluminum or Stainless Steel
• Color Options: Aluminum: Silver, Space Gray, Gold | Stainless Steel: Silver, Space Black, Gold
• Release Date: September 2018
• Status: Discontinued (no longer sold by Apple)

Display

• Screen Size: 1.57 inches (40mm) diagonal
• Display Type: Retina LTPO OLED
• Resolution: 324 × 394 pixels
• Brightness: Up to 1000 nits
• Always-On Display: No (introduced in Series 5)
• Screen Protection: Ion-X strengthened glass (aluminum) or Sapphire crystal (stainless steel)
• Features: 30% larger display than Series 3 38mm, edge-to-edge design, rounded corners

Processor & Memory

• Chipset: Apple S4 SiP (System in Package)
• Processor: Dual-core 64-bit (up to 2x faster than S3)
• Storage: 16GB
• Wireless Chip: Apple W3 wireless chip

Sensors

• Electrical heart sensor: For ECG app (first Apple Watch with this feature)
• Optical heart sensor: Second generation, for heart rate monitoring
• Accelerometer: Up to 32 g‑forces with improved fall detection
• Gyroscope:
• Barometric altimeter: For elevation tracking
• Ambient light sensor: For automatic brightness adjustment
• Note: No blood oxygen sensor (introduced in Series 6)

Health & Fitness Features

• ECG App: First Apple Watch to feature ECG capability (cleared by FDA)
• Heart Rate Monitoring: High and low heart rate notifications, irregular rhythm notifications
• Fall Detection: Automatically call emergency services if hard fall detected
• Emergency SOS: Call emergency services with side button hold
• Workout Types: Multiple workout types including swimming, yoga, hiking
• Activity Rings: Move, Exercise, Stand rings with sharing and competitions
• Water Resistance: Swimproof - suitable for pool and open water swimming
• Elevation Tracking: With built-in altimeter
• Noise Monitoring: Available with watchOS 6 or later
• Cycle Tracking: Available with watchOS 6 or later

Connectivity

• Cellular: LTE and UMTS support (with cellular model)
• Wi-Fi: 802.11b/g/n 2.4GHz and 5GHz
• Bluetooth: 5.0
• GPS/GNSS: Built-in GPS, GLONASS, Galileo, and QZSS
• NFC: For Apple Pay
• Emergency SOS: International emergency calling
• Compatibility: iPhone 6s or later with iOS 12 or later

Smart Features

• Siri: Voice assistant with raise-to-speak, faster response
• Phone Calls: Make and receive calls directly from watch (with cellular model)
• Messages: Send and receive messages, Digital Touch, and animated emoji
• Apple Pay: Contactless payments
• Walkie-Talkie: Live voice communication with other Apple Watch users
• Maps: Turn-by-turn navigation with haptic feedback
• Music & Podcasts: Stream and download for offline playback
• Audible: Listen to audiobooks
• Find My: Locate people, devices, and items
• Noise Monitoring: Alerts when ambient sound levels are too high
• Emergency Features: Fall Detection, Emergency SOS

Battery

• Battery Type: Built-in rechargeable lithium-ion
• Battery Life: Up to 18 hours (all-day battery life)
• Charging: Magnetic charging cable (USB-A connector included)
• Charging Time: 0 to 80% in about 1.5 hours, 0 to 100% in about 2.5 hours
• Power Reserve: Time-only mode extends battery life

Water Resistance

• Rating: Water resistant 50 meters under ISO standard 22810:2010
• Swimproof: Suitable for swimming in a pool or ocean
• Water Lock: Ejects water from speaker after swimming
• Not Suitable For: Scuba diving, water skiing, or other activities involving high-velocity water

Physical Specifications

• Dimensions: 40mm height × 34mm width × 10.7mm depth
• Weight: Aluminum: 30.1 grams | Stainless Steel: 39.8 grams (with sport band)
• Case Material: Aluminum or Stainless Steel
• Back Material: Ceramic and sapphire crystal (with heart rate sensors)
• Strap Compatibility: All Apple Watch bands (40mm, 41mm, 45mm, 49mm - some may need sizing)
• Digital Crown: Redesigned with haptic feedback
• Side Button: Redesigned and flush with case
• Speaker: 50% louder than previous models

Operating System

• Original OS: watchOS 5
• Latest Supported OS: watchOS 9 (final update)
• Note: Does not support watchOS 10 or later

Audio & Haptics

• Speaker: 50% louder with redesigned speaker for clearer calls and Siri
• Microphone: Relocated to opposite side of speaker for better call quality
• Haptic Feedback: Redesigned Taptic Engine with more distinctive vibrations

Environmental Requirements

• Operating Temperature: 32° to 95° F (0° to 35° C)
• Storage Temperature: -4° to 113° F (-20° to 45° C)
• Relative Humidity: 5% to 95% noncondensing
• Maximum Operating Altitude: Tested up to 10,000 feet (3000 m)

In the Box

• Apple Watch Series 4 (GPS + Cellular, 40mm)
• Sport Band (size: S/M and M/L) or other band depending on configuration
• 1m Magnetic Charging Cable (USB-A)
• 5W USB Power Adapter
• Documentation

Warranty & Support

• Limited Warranty: 1 year
• AppleCare+: Optional extended warranty (if purchased within 60 days)
• Software Support: Received updates until watchOS 9 (2022-2023)
• Current Status: Vintage product (limited hardware service available)

Certifications

• Water resistant 50m (ISO 22810:2010)
• CE, FCC, ICES, MIC, RCM, UKCA
• ECG app cleared by FDA (US) and other regulatory bodies

Key Improvements Over Series 3

• 30% larger display with edge-to-edge design (compared to 38mm Series 3)
• First Apple Watch with ECG capability
• Faster dual-core S4 processor (up to 2x faster)
• Improved accelerometer and gyroscope for fall detection
• 50% louder speaker
• Redesigned Digital Crown with haptic feedback
• Ceramic and sapphire crystal back (improved cellular reception)
• Bluetooth 5.0 (upgrade from 4.2)
• 16GB storage (double the Series 3)

Comparison with 44mm Series 4

• Display Size: 1.57" vs 1.78" (44mm)
• Resolution: 324 × 394 vs 368 × 448 pixels
• Weight: Aluminum: 30.1g vs 36.7g | Stainless Steel: 39.8g vs 47.9g
• Dimensions: 40 × 34 × 10.7mm vs 44 × 38 × 10.7mm
• Battery: Slightly smaller battery (for smaller case)
• Best For: Smaller wrists, those preferring more compact wear

Important Notes & Limitations

• Ideal for users with smaller wrists (wrist circumference approximately 130-200mm)
• Does not support latest watchOS versions (stuck on watchOS 9)
• No Always-On Display (introduced in Series 5)
• No blood oxygen monitoring (introduced in Series 6)
• No U1 Ultra Wideband chip (introduced in Series 6)
• No family setup (requires watchOS 7+ on Series 4 or later with cellular)
• Cellular service requires carrier plan and iPhone setup
• ECG app not intended for users under 22 years old
• Considered vintage by Apple as of 2023
• Some features require iPhone and/or internet connection
• Battery life varies by use, cellular connectivity, and other factors
• Smaller display may be less readable for some users compared to 44mm model