The Apple Watch Series 4 was unveiled at the company's 12 Sept iPhone XS launch event and is now available to buy. It's been substantially redesigned, upgraded internally, and equipped with a range of new health and fitness features.

In this article we've got everything you need to know about the new Apple Watch for 2018: its release date, price, specs, design and new features.

For related advice, take a look at our Apple Watch buying guide.

The UK Tech Weekly Podcast discuss the Series 4 in episode 102:

Apple Watch 4 release date

The Series 4 was announced on 12 Sept 2018 (alongside new iPhones). It went on sale on 21 Sept.

You can buy from Apple or from various networks and resellers such as EE, Vodafone and Currys PC World. Read our best Apple Watch deals roundup for the best places to buy.

Apple Watch Series 4 release date, price & specs

Apple Watch 4 prices

The Series 4 starts at £399/$399 (with GPS) or £499/$499 (with cellular). Here's the line-up:

Material Strap 40mm, GPS 44mm, GPS 40mm, cellular 44mm, cellular Buy link
Aluminium Sport Band £399/$399 £429/$429 £499/$499 £529/$529 Apple Store
Aluminium Sport Loop £399/$399 £429/$429 £499/$499 £529/$529 Apple Store
Aluminium Nike Sport Band £399/$399 £429/$429 £499/$499 £529/$529 Apple Store
Aluminium Nike Sport Loop £399/$399 £429/$429 £499/$499 £529/$529 Apple Store
Steel Sport Band n/a n/a £699/$699 £749/$749 Apple Store
Steel Sport Loop n/a n/a £699/$699 £749/$749 Apple Store
Steel Milanese Loop n/a n/a £799/$799 £849/$849 Apple Store
Steel Hermes Leather Single n/a n/a £1,249/$1,249 £1,299/$1,299 Apple Store
Steel Hermes Leather Double n/a n/a £1,399/$1,399 n/a Apple Store
Steel Hermes Leather Rallye n/a n/a n/a £1,399/$1,399 Apple Store
Steel Hermes Leather Deployment Buckle n/a n/a n/a £1,499/$1,499 Apple Store

Note that for each model above there will be numerous colour combinations. Read the full price list on Apple's website.

Before the event, the Series 3 started at £399/$399 (with cellular) or £329/$329 (without), but it gets a price cut as part of the Series 4 launch. It now starts at $279/£279.

Design

Apple kept the same design for three generations in a row (aside from some minor cosmetic tweaks, such as a new material and colour options, and a red spot on the cellular model). We were therefore expecting a major redesign for the Series 4 - and we got precisely that.

Larger screen

The most obvious change is the inclusion of screens which are more than 30% larger. They're now 40mm and 44mm (up from 38mm and 42mm).

Apple has achieved this by reducing the size of the bezels around the edge. The screen also has curved corners, fitting more closely to the shape of the face.

Apple Watch Series 4 release date, price & specs: Larger screens

The new watches are slimmer than the Series 3, which means that despite the larger screens they have less volume than their predecessors. Note, however, that straps released with the Series 3 and earlier models are compatible with the Series 4, and vice versa.

Apple watch Series 3 vs Series 4

Colours & materials

The Series 4 is available in stainless steel or aluminium; the all-ceramic Edition offering has been quietly dropped.

The aluminium models are available in silver, gold and Space Grey. If you go for stainless steel your options are 'polished', Space Black and a new gold.

We said ceramic is gone, but the steel and aluminium models now have black ceramic undersides. This is significant because it allows radio waves to pass through and should lead to improved cellular reception.

Digital Crown

The Crown has been redesigned too, and now features haptic 'click' feedback as the dial is turned. Apple says this will allow for more accurate scrolling.

Speaker & microphone

Finally, the speaker has been bumped up - the company says it's 50% louder now - and the microphone aperture has swapped sides to move it away from the speaker. Hopefully this will all result in much better call quality.

Watch faces

Some intriguing updates here, mainly to take advantage of the larger screens.

The Breathe app now has its own face (and three different graphical variations).

Apple Watch Series 4 release date, price & specs: Breathe face

There are new dynamic faces with fire, water and vapour graphics (the latter two look gorgeous).

Apple Watch Series 4 release date, price & specs: Vapour face

And you can now have up to eight complications on the face.

Apple Watch Series 4 release date, price & specs: Complications

Health features

Apple described the watch as "an intelligent guardian for your health", and backed that up with a raft of health-related updates.

Fall detection

The Series 4 is clever enough to work out when you're falling - it works this out from the movement of your arms, which are different when falling to when slipping or doing other similar actions.

If you fall and then remain still for a certain time, it will assume that something bad has happened and contact the emergency services and send your location to your emergency contacts using the SOS feature.

Apple Watch Series 4 release date, price & specs: Fall detection

Heart monitoring

The Apple Watch already had the ability to detect and warn of a prolonged elevated heart rate when not exercising, but its heart-monitoring abilities get far more sophisticated with the Series 4 update.

Most simply, it will now be able to spot low rates too - less commonly a problem, but potentially something to look out for. The 4 will also look out for irregular heart rhythms, notifying you of a potential atrial fibrillation.

Apple Watch Series 4 release date, price & specs: Atrial fibrillation

But the biggest interest was shown for a new ECG function. By placing a finger on the Digital Crown you can get the watch to run an ECG test on you, which Apple says marks the first time an ECG device has been made available over the counter direct to consumers.

Note, however, that the ECG function requires a separate app, and this will not be available at launch. Apple says only that it is "coming later this year".

Apple Watch Series 4 release date, price & specs: ECG

All of the health-related data is stored in the Heath app, and the company was at pains to reassure customers that their privacy will be protected. Patients visiting their doctors will often complain of heart problems that aren't happening at that moment, so having detailed and long-term heart data on file is potentially very useful.

Tech specs

Processor

The Series 4, as expected, comes with an S4 processor chip. Apple says this offers twice the speed of the previous generation.

Battery

Battery life remains the same, with Apple somehow managing to make a virtue of this. The company still claims 18 hours, which we suppose is reasonably impressive given the larger screen, upgraded components and thinner body.

Nevertheless, better battery life would have opened up more functionality, mainly with regards to sleep tracking. One problem with the Apple Watch is that the necessity of charging it at night means that people can't use it for sleep tracking. With a longer battery life, users could wear the watch to bed and get accurate stats about their sleep - information that's pretty popular, judging by the success of sleep-tracking apps such as Sleep Cycle.

Software

The new Apple Watch will come with watchOS 5 preinstalled. This was announced at WWDC 2018 on 4 June and released on 17 Sept.

watchOS 5 brings a range of new features and interface tweaks to the Apple Watch. These will be optimised to run best on the new Series 4 hardware, but owners of most Apple Watch models (all but the original) will be able to upgrade and get the new features for free.