Will an AI model run on my iPhone?

Why some models crash and others don't

Running an AI model on a phone is different from running an app. The model has to be held in memory the whole time it's thinking, and iOS is strict about how much memory it will let a single app hold. Ask for more than your allowance and iOS shuts the app down — no error message, it just disappears.

That's why the same model can be flawless on one iPhone and unusable on another. It isn't about how new your phone is, and it isn't something you can fix by closing other apps. It comes down to how much memory your particular iPhone has, and how large the model is.

The practical version: bigger models are smarter and need more phone. Smaller models are faster, cooler, kinder to your battery, and run almost anywhere. The trick is finding the largest one your iPhone is comfortable with — and not going past it.

A rough guide

Every model is offered in a few sizes. As a very general rule:

Model size	What it's like	Who it suits
Small	Quick and light. Good at summarizing, rewriting, tidying up notes and answering simple questions.	Older iPhones, and anyone who wants instant answers without warming the phone up
Medium	The everyday sweet spot. Noticeably better writing and more reliable answers.	Most iPhones from the last few years
Large	The most capable option, at the cost of speed, battery and warmth.	Recent Pro iPhones, for people who want the best answers and don't mind waiting

One thing that surprises people: a "Pro" iPhone from several years ago often handles larger models better than a standard iPhone released the same year. Newer isn't automatically better here.

You don't have to work any of this out

This is exactly the part the app takes care of. Open the model list and every model is already marked for your iPhone — whether it will run comfortably, whether it will be a stretch, or whether it's simply too much for this device. You see that before you spend time and data on a download.

If you're not sure where to start, the app suggests a good default for your phone the first time you open it. Most people never need to think about it again.

Getting the best out of it

Start smaller than you think. A fast, reliable answer beats a slightly better one that takes three times as long.
Long conversations get heavier. If a very long chat starts to struggle, begin a fresh one — it's an easy fix.
Expect some warmth. Any phone doing this work heats up a little. Smaller models cost far less battery.
Download on Wi-Fi. Models are large files. Grab one at home and you'll never need a connection again.

Download on the App Store What the app does

Free for three days, then a one-time purchase. iOS 17 or later.