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Why the iPhone 15 won’t support Apple AI in iOS 18, and why that’s OK

Published Jun 12th, 2024 6:50AM EDT
Apple Intelligence feature summary.
Image: Apple Inc.

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The wait is over. iOS 18 is official, and you can install the first beta on your iPhone right now. The new operating system brings several exciting features to the iPhone, though Apple Intelligence, the suite of AI features Apple built into iOS 18, will be available only later this year.

When Apple AI launches, it will be a beta release with specific hardware requirements. You’ll need an iPhone 15 Pro or 15 Pro Max to run Apple Intelligence, or you can wait for the iPhone 16 to roll out.

That’s right, the 2023 iPhone 15 and iPhone 15 Plus aren’t good enough for Apple AI. It might sound annoying if you’re a fan of products like ChatGPT and are excited about the smarter Siri coming to the iPhone. But it turns out there’s a simple explanation for that, one I probably guessed correctly: The RAM.

Hours before the main WWDC keynote, I explained that iPhone memory might be Apple’s biggest problem when deploying the kind of on-device AI it wants. That is safe, personal, and private on-device AI. Rumors preceding the show said the iPhone 15 Pro and 15 Pro Max would be the bare minimum for running Apple Intelligence, and they were correct. The bottleneck, I guessed, was RAM.

Now that WWDC is over and the Apple Intelligence hardware requirements are official, we have new insight from well-known insider Ming-Chi Kuo into Apple’s memory problem.

Why you can’t run Apple AI on the iPhone 15

Kuo explained in a blog post that RAM is probably the main reason why the iPhone 15/Plus can’t run Apple AI:

The iPhone 15 with the A16 chip cannot support Apple Intelligence, but M1-equipped models can. Therefore, it can be concluded that the key to supporting the current Apple Intelligence on-device model is the DRAM spec rather than computing power (TOPS).

The AI computing power of the M1 is about 11 TOPS, lower than the 17 TOPS of the A16. The A16 has 6GB of DRAM, lower than the 8GB of the M1. Therefore, current Apple Intelligence on-device AI LLM require about 2GB or less of DRAM.

Siri gets an AI-powered upgrade in iOS 18.
Siri gets an AI-powered upgrade in iOS 18. Image source: Apple Inc.

Kuo further theorized that Apple uses a 3-billion parameter large language model (LLM) to power on-device AI. Therefore, Apple needs at least 2GB of RAM dedicated to the AI:

The demand for DRAM can be verified in another way. Apple Intelligence uses an on-device 3B LLM (which should be FP16, as the M1’s NPU/ANE supports FP16 well). After compression (using a mixed 2-bit and 4-bit configuration), approximately 0.7-1.5GB of DRAM needs to be reserved at any time to run the Apple Intelligence on-device LLM.

Kuo also explained that Apple’s way of clearly defining on-device AI is better than Microsoft’s more confusing requirements for the new AI PCs. Microsoft focuses on TOPS performance rather than RAM. I’ll add that memory isn’t a problem on laptops.

The insider predicted that Apple will need to upgrade its AI models to a 7-billion LLM in the future. If that comes true, future iPhones will need even more RAM than the 8GB of memory found inside the iPhone 15 Pros. All iPhone 16 variants should also come with 8GB of RAM.

Why it’s good news

I’m currently using an iPhone 14 Pro that runs iOS 18 beta 1 exceptionally well. The hardware is on par with the iPhone 15, so it won’t get Apple Intelligence. What I’m getting at is that I feel your pain, iPhone 15/Plus owners. Then again, I’m already set on buying an iPhone 16 this fall, with Apple AI being the primary factor.

But I’ll point out something very important for my AI experience. I want as many AI features to run locally, on the iPhone. I want Apple to guarantee that privacy. If that means having to upgrade the hardware, then so be it. I will pay for great AI one way or another. Apple won’t charge a subscription for Apple AI yet, but I’ll need a brand-new iPhone to get it.

I’ll also point out the not-so-obvious. Apple seems to have been largely oblivious to the rapid advancement of AI and what it’ll mean for iPhone software and hardware. That would explain why the iPhone 15/Plus were not futureproofed for that. The iPhone 15 specs were probably decided long before it became clear to Apple that it’ll need its own version of AI running on iPhones via iOS 18.

Then again, not everyone will want Apple AI on iPhones. There will be a big divide between iOS experiences in the coming years. But even so, iOS 18 has plenty of non-AI amazing features you can test immediately.

Chris Smith Senior Writer

Chris Smith has been covering consumer electronics ever since the iPhone revolutionized the industry in 2008. When he’s not writing about the most recent tech news for BGR, he brings his entertainment expertise to Marvel’s Cinematic Universe and other blockbuster franchises.

Outside of work, you’ll catch him streaming almost every new movie and TV show release as soon as it's available.