Will New Siri Work Better on Older iPhones?

Apple Intelligence features, including the updated Siri, are currently restricted to devices equipped with the A17 Pro chip or later, meaning iPhone 15 Pro, iPhone 15 Pro Max, and all iPhone 16 models. While users of older hardware may experience performance limitations or total exclusion from these generative AI capabilities, Apple maintains that the hardware requirements are necessary to support the on-device processing demands of the new models.

Hardware Requirements for Apple Intelligence

The rollout of Apple Intelligence represents a significant shift in how the company manages on-device processing. According to Apple’s official documentation, the new Siri and associated AI features rely heavily on the Neural Engine found in the A17 Pro chip and the A18 series. These silicon architectures are designed to handle the high memory bandwidth and computational throughput required for large language models (LLMs) to run locally on a smartphone.

Devices such as the iPhone 15 and earlier models, which utilize the A16 Bionic chip or older, lack the specific hardware configuration Apple deems necessary for a responsive AI experience. When Apple released the first developer and public betas for iOS 18.1, users with unsupported devices found that these features were simply unavailable. For those with supported devices, the initial beta versions have occasionally exhibited latency, which Apple typically addresses through iterative software optimization and firmware updates during the testing cycle.

Why Older iPhones Cannot Run the New Siri

The primary barrier for older hardware is not just raw processing speed, but the specific architecture of the Apple Neural Engine and the availability of unified memory. Apple has stated that its AI model deployment involves both on-device processing and "Private Cloud Compute" for more complex requests.

• Memory Bandwidth: Running generative AI models requires significant amounts of high-speed RAM. Newer iPhone models feature upgraded memory architectures that facilitate these tasks without slowing down other system processes.
• Neural Engine Performance: The A17 Pro and A18 chips feature a significantly more powerful Neural Engine compared to their predecessors, specifically optimized for transformer models that power the new Siri.
• Thermal Constraints: Running intensive AI tasks on older processors can lead to rapid battery drain and thermal throttling, which would degrade the user experience.

Managing Expectations for Beta Software

Users participating in the iOS 18 beta program often report performance inconsistencies. It is standard for early-stage software to lack the final optimizations that arrive in the public release. Apple engineers focus on power efficiency and model quantization—a technique that reduces the size of AI models to make them run faster on mobile hardware—throughout the beta period.

For users currently experiencing slow performance on supported devices, Apple typically recommends ensuring the device is updated to the latest beta build, as these releases often include bug fixes for the Siri interface and the underlying AI frameworks.

Summary of Apple Intelligence Compatibility

Users with devices older than the iPhone 15 Pro will continue to use the legacy version of Siri. While Apple has not announced plans to backport the full suite of Apple Intelligence features to older silicon, the company continues to provide security updates and functional improvements for existing Siri commands across all supported iOS 18 devices.