# A 1TB iPhone 18 Pro Max turned up with slower QLC storage

Source: https://idevice.com/a-1tb-iphone-18-pro-max-turned-up-with-slower-qlc-storage
Published: 2026-09-22

> A stress test hit 1.1MB/s once the fast cache ran out, which matters for long ProRes recordings. Apple doesn't say which storage chip a phone ships with, and supply looks mixed.

A 1TB [iPhone 18 Pro Max](https://idevice.com/phones/iphone-pro/roadmap/iphone-18-pro-max) has turned up with a slower kind of flash storage than a 512GB [iPhone 18 Pro](https://idevice.com/phones/iphone-pro/roadmap). HOMOLAB found QLC NAND in the 1TB Pro Max it took apart and stress-tested, and TLC NAND in the 512GB Pro, per The Mac Observer.

QLC packs more data into each memory cell, and it slows down sharply once the fast cache in front of it fills up. HOMOLAB pushed the phone to exactly that point. The 1TB Pro Max was filled to about 60 percent before its caches ran out. Writing straight to the QLC after that, it averaged about 45MB/s and briefly fell as low as 1.1MB/s.

Nobody hits that saving a photo or installing an app, and someone shooting short clips may never get there. Long recordings are different. The Pro models record ProRes video at up to 4K and 120 frames a second, along with ProRes RAW and Apple Log 2, and those formats write huge files for as long as the camera is rolling.

Apple doesn't list the NAND type in its specifications or at checkout, and supply appears to be mixed between QLC and TLC. So one 1TB phone with QLC doesn't mean every 1TB phone has it. One 512GB phone with TLC doesn't guarantee the rest do either. HOMOLAB didn't test a 2TB model at all.

Apple also doesn't publish how much of each tier is usable once the system takes its share. That makes a 60 percent threshold hard to turn into minutes of footage on any given phone.

The top ProRes mode, 4K at 120 frames a second, already has to be recorded to an external drive, so that footage never touches the phone's own storage. Every mode below it still does.