Apple is just days away from revealing the latest additions to its iPhone line-up as the technology giant upgrades its flagship smartphone.

The US company will on Tuesday unveil its new iPhone 15 and iPhone 15 Pro, updating last year’s iPhone 14 handsets. It is also expected to upgrade its Apple Watch line up.

The iPhone-maker will host its launch event, called “Wanderlust”, at the Steve Jobs Theatre at Apple Park in California.

The event comes at a key moment for Apple as global demand for new smartphones slumps to its lowest point in a decade. Apple has also grappled with its longest smartphone sales slump since 2016 after iPhone revenues fell over the summer.

Here is everything you need to know about the iPhone 15 launch:

When will the iPhone 15 be launched and where can I watch?

The iPhone 15 event will take place at 6pm BST on Tuesday September 12 – or 10am local time in California. You will be able to watch the livestream on YouTube.

What is the release date for the iPhone 15?

Each new iPhone is typically announced on a Tuesday. Pre-orders then go live on the Apple Store later that week – and are expected to begin for the iPhone 15 on Friday September 15. The phone will then go on wider sale with networks on Friday September 22.

Apple is expected to launch two iPhone 15 Pro models – one regular sized iPhone 15 Pro with a 6.1-inch display and a larger iPhone 15 Pro Max model with a 6.7-inch screen – and two slightly less powerful smartphones – the iPhone 15 and iPhone 15 Plus.

Supply chain analysts have suggested the release of the iPhone 15 Pro Max could come a little later than the others, perhaps in October. Bloomberg also previously reported Apple could rebrand the phone from the “Max” to the “Ultra”.

What are the best new features of the iPhone 15?

The new iPhone 15 is likely to be a modest upgrade compared to previous generations of the iPhone, which was first introduced back in 2007, although all four models will see tweaks compared to the iPhone 14 line-up.

While rival phone makers have brought back fingerprint sensors by embedding them in the phone’s screen or on the back of the phone, Apple is not expected to follow suit.

The iPhone 15 range will also come with an upgraded microchip, the A17 bionic. The chip is expected to be a cutting-edge 3 nanometre processor manufactured by Taiwanese company TSMC, according to a report in Japan’s Nikkei newspaper. The more efficient chip should also boost the phone’s battery life.

The Pro models of the phone will be built with a titanium frame, instead of stainless steel, which should make them more durable as well as lighter, according to Bloomberg.

Analysts now expect all of Apple’s iPhones to come with its so-called “dynamic island” screen design. This does away with the “notch” at the top of older models since the iPhone X. Instead, it will have an adaptive display around a punch-hole camera at the top of the phone.

Analysts at Nomura believe the cameras on the entry level iPhone 15 and 15 Plus models will feature  significant upgrades, including a more powerful wide camera with 48MP. Its more advanced iPhone 15 Pro models will come with further enhancements - these are expected to include a “periscope” camera lens that can provide greater zoom - according to analysts at Trendforce. “The star of the show will be the camera upgrades - a pivotal factor that could tip the scales for potential buyers,” the analysts said.

Renders leaked to 9to5Mac suggest all this camera hardware will lead to a bigger “bump” at the back of the phone. The glass screen will also curve slightly around the edges. Several reports also claim the current mute button on the side of the phone will be replaced with a more versatile “action” button, which can be programmed for different functions.

The company’s iOS 17 software, its latest update to the iPhone’s operating system, is expected to be released in time for the iPhone 15’s launch. Some new features include a journal app, which Apple describes as a “new app to write and remember”.

How will the charging cable change for the iPhone 15?

Perhaps the biggest change people will notice is the new charging cable and port.

Apple has been forced to stop using its own “lightning” charging cables thanks to an EU law aimed at combating e-waste by bringing in a common standard for chargers. The new rules were due to force Apple to make the change by 2024.

The new iPhone will instead use a technology known as USB-C, according to Bloomberg. The European diktat has compelled Apple to make the switch globally, rather than just limiting it to the EU.

While this kind of charging port has a proven track record for fast-charging phones, it might mean some of your old cables are no longer useful. Still some other Apple devices, such as its MacBook line-up, already use USB-C, and the standard is common for smartphones including most Android devices.

What about the Apple Watch?

Apple is also anticipated to upgrade its Watch line-up to the Apple Watch Series 9 with a more powerful processor. It remains to be seen whether it will also upgrade the Apple Watch Ultra, its more sporty, durable version, that was first released last year.

With the upgrade to USB-C on Apple’s iPhones, there are also expectations of a revamp of its AirPod headphones. At the very least, it might update the charging case for the new kind of wire.

Apple fans will also be looking out for any new details about Apple’s VR headset - the Vision Pro - which was teased earlier this summer but is not expected to be released until next year.

How much will the iPhone 15 cost?

We don’t know yet how much the new iPhone will cost, but all signs suggest it could get a little more expensive. The current iPhone 14 cost £849, while its iPhone 14 Pro model started at £1,099. Those prices made headlines last year after inflation pushed up the price of Apple’s new phones. The iPhone 14 Pro jumped by £150 compared to its equivalent the iPhone 13 Pro, while the regular 14 was £70 more expensive.

Analysts at Barclays expect the iPhone 15 line-up to come in at a higher price point - around $100 more for the iPhone 15 Pro and between $100 to $200 more for the iPhone15 Pro Max.

It remains to be seen whether inflation will have pushed the price up any further.