Apple Watch Series 4 Aluminium

Quick Facts

Item	Details
Launch Year	2018
Case Material	Aluminium
Available Sizes	40mm, 44mm
Display	LTPO OLED Retina Display (324 × 394 / 368 × 448)
Processor	Apple S4 SiP
Connectivity	GPS or GPS + Cellular
Battery Life	Up to 18 hours
Water Resistance	50m (WR50)
Health Features	Heart Rate, ECG, Fall Detection
Glass	Ion-X Strengthened Glass
Storage	16GB
Weight	30.1g (40mm), 36.7g (44mm)
Compatibility	iPhone only

Overview

The Apple Watch Series 4 Aluminium is a great choice for iPhone users looking for an affordable smartwatch with fitness tracking, health monitoring and everyday smart features. It introduced a larger edge-to-edge display, ECG and Fall Detection, making it a significant upgrade over earlier Apple Watch models.

Powered by the Apple S4 SiP, it features a bright Retina display, built-in GPS, optional GPS + Cellular connectivity, up to 18 hours of battery life and 50m water resistance. When buying a used Apple Watch, check the battery condition, Activation Lock status and overall physical condition before making your purchase.

Why Choose Apple Watch Series 4 Aluminium?

1. Advanced Health & Safety Features

Apple Watch Series 4 introduced ECG and Fall Detection, giving users more health insights and added peace of mind.

Why it matters

ECG supports heart rhythm monitoring
Fall Detection adds an extra layer of safety
Tracks daily activity and workouts

2. Larger Retina Display

The larger edge-to-edge Retina display makes notifications, apps and workout information easier to read.

Why it matters

More screen space for apps
Easier to read notifications
Better visibility outdoors

3. Built-in GPS for Outdoor Workouts

Built-in GPS accurately tracks your outdoor activities without requiring your iPhone nearby.

Why it matters

Tracks distance and pace
Records outdoor workout routes
Ideal for walking, running and cycling

Key Features Explained

Feature	Specification	Why It Matters
Display	LTPO OLED Retina Display	Bright and easy to read indoors and outdoors
Processor	Apple S4 SiP	Smooth everyday performance
Battery Life	Up to 18 hours	Suitable for a full day’s typical use
Charging	Magnetic Charging Cable	Simple and convenient charging
Water Resistance	50m (WR50)	Suitable for swimming but not diving
GPS	Built-in GPS	Tracks outdoor workouts without your iPhone
Cellular	GPS or GPS + Cellular	Cellular models stay connected without your iPhone (carrier support required)
Health Features	Heart Rate, ECG, Fall Detection	Supports health monitoring and safety features
Glass	Ion-X Strengthened Glass	Lightweight and durable for everyday wear
Compatibility	iPhone only	Apple Watch is not compatible with Android phones

GPS vs GPS + Cellular

Feature	GPS	GPS + Cellular
Built-in GPS	✓	✓
Make calls without iPhone	✗	✓
Send messages	✗	✓
Mobile data	✗	✓
Requires mobile plan	No	Yes
Best For	Users who carry their iPhone	Users who want to stay connected without their iPhone

Which should you choose?

Choose the GPS model if your iPhone is usually with you. Choose the GPS + Cellular model if you want to make calls, send messages and stay connected without carrying your iPhone (supported carrier and mobile plan required).

Compare the Related Models

Feature	Apple Watch Series 3 Aluminium	Apple Watch Series 4 Aluminium	Apple Watch Series 5 Aluminium	Apple Watch SE (1st Generation) Aluminium
Launch Year	2017	2018	2019	2020
Display	OLED Retina	LTPO OLED Retina	Always-On LTPO OLED Retina	Retina OLED
Processor	Apple S3	Apple S4	Apple S5	Apple S5
Health Features	Heart Rate	Heart Rate, ECG, Fall Detection	Heart Rate, ECG, Fall Detection	Heart Rate, Fall Detection
Battery Life	Up to 18 hours	Up to 18 hours	Up to 18 hours	Up to 18 hours
Storage	8GB / 16GB	16GB	32GB	32GB
Water Resistance	50m	50m	50m	50m
Connectivity	GPS / GPS + Cellular	GPS / GPS + Cellular	GPS / GPS + Cellular	GPS / GPS + Cellular
Glass	Ion-X	Ion-X	Ion-X	Ion-X
Weight	26.7g / 32.3g	30.1g / 36.7g	30.8g / 36.5g	30.5g / 36.4g

Which Apple Watch Should You Choose?

Model	Recommended For
Apple Watch Series 4 Aluminium	Buyers who want ECG, Fall Detection and excellent value for money.
Apple Watch Series 5 Aluminium	Buyers who want an Always-On Display and more storage.
Apple Watch SE (1st Generation) Aluminium	Buyers who want newer hardware and longer software support.
Apple Watch Series 3 Aluminium	Budget buyers looking for essential fitness tracking.

Alternatives to Apple Watch Series 4 Aluminium

If you’re comparing before buying, you may also want to check these related SellUp Marketplace pages:

Common Questions

Is the Apple Watch Series 4 Aluminium still worth buying?

Yes. It remains a great option for iPhone users who want ECG, Fall Detection, fitness tracking and smart notifications at an affordable price. When buying used, check the battery condition and ensure Activation Lock has been removed.

What is the difference between GPS and GPS + Cellular?

The GPS model connects through your iPhone for calls and mobile data when you’re away from Wi-Fi. The GPS + Cellular model can make calls, send messages and use mobile data independently with a supported carrier and mobile plan.

Is the Apple Watch Series 4 Aluminium waterproof?

The Apple Watch Series 4 Aluminium has a 50m (WR50) water resistance rating, making it suitable for swimming. It is not intended for diving or high-pressure water sports. Water resistance may also decrease over time on used devices.

Is the Apple Watch Series 4 Aluminium better than the Apple Watch Series 5 Aluminium?

The Apple Watch Series 5 Aluminium adds an Always-On Display, built-in compass and 32GB of storage. If you want the best value, the Series 4 remains an excellent choice. If an Always-On Display is important, the Series 5 is the better option.

Why Buy the Apple Watch Series 4 Aluminium?

The Apple Watch Series 4 Aluminium continues to be one of the best-value Apple Watches for iPhone users. It combines ECG, Fall Detection, built-in GPS and reliable fitness tracking in a lightweight aluminium case. Compare Apple Watch Series 4 Aluminium listings on SellUp Marketplace to find the condition, case size, connectivity option (GPS or GPS + Cellular) and price that best suit your budget.