iPhone Duo Touch ID: what Apple says and what reviewers found

iPhone Duo is the first new iPhone with Touch ID since the third-generation iPhone SE arrived in March 2022, MacRumors noted at launch. This time the fingerprint sensor sits in the side button, and Apple's iPhone Duo spec page lists a Touch ID fingerprint sensor but no Face ID.

That makes Touch ID the one built-in biometric on iPhone Duo, so it handles unlocking, Apple Pay and password approvals. Here is what Apple claims, what reviewers reported, and who will mind.

What Apple says about Touch ID on iPhone Duo

Apple's spec page describes a fingerprint sensor built into the side button and says you can pay with Touch ID in stores, within apps and on the web. In Apple's September 9 announcement, Apple calls the side-button sensor "easy, secure, and consistent authentication" whether iPhone Duo is open or closed.

The same announcement says owners can also unlock iPhone Duo with an Apple Watch. On Oct 23, 9to5Mac reported that Apple published iPhone Duo support documents, including ones titled "About genuine Touch ID buttons for iPhone Duo" and "iPhone Duo Troubleshooting Button Issues."

Why doesn't iPhone Duo have Face ID?

Apple hasn't said. The explanation that circulated before launch traces to analyst Ming-Chi Kuo, who reportedly said in a March 2025 report that the foldable would use side-button Touch ID; MacRumors said the choice appeared driven by space constraints in the thin design. A later AppleInsider report on a December 2025 leak from Weibo account Digital Chat Station made a similar argument about the depth Face ID hardware needs.

Both are reports, not Apple statements. Whether Face ID comes to a later model is still rumor territory, and the confirmed vs. reported tracker for iPhone Duo 2 keeps those claims separate.

The built-in pause, and how to shorten it

Several reviewers reported that Touch ID on iPhone Duo waits a beat before unlocking. According to a MacRumors roundup of reviewer complaints, Apple told Engadget the pause gives a consistent experience across its Touch ID devices, such as Macs and iPads, and gives the phone time to wake and show Lock Screen notifications. The same roundup says Marques Brownlee called the delay technically smart but still missed Face ID.

There is a setting that trims a step. MacRumors explains that turning on Rest Finger to Open, in Settings > Touch ID & Passcode or Settings > Accessibility > Side Button, lets you unlock, with the screen awake, by resting a finger on the side button without swiping up afterward.

What reviewers found in practice

The good news first. Macworld's Britta O'Boyle wrote in her week-one piece that Touch ID unlocked reliably whether the phone was open or closed. In 9to5Mac's review, Chance Miller enrolled both thumbs and both index fingers so it worked in any grip, and found it easiest with the phone lying flat on a table. MacRumors reports The Verge found a week was long enough to adjust.

The criticism is consistent, though. MacRumors quotes Marques Brownlee predicting "Face ID is going to be the number one thing people miss" (more in the MKBHD review summary). Per the same roundup, Joanna Stern was still fumbling unlocks a week in with five fingers enrolled (see the Joanna Stern video summary), and Mrwhosetheboss found it could be problematic right after washing his hands or with slightly greasy fingers (see the Mrwhosetheboss summary). Gizmodo's Raymond Wong noted that winter gloves have to come off, MacRumors adds.

Macworld's Jason Cross put the mixed feeling plainly in his full review: "I can live with Touch ID on this thing, but I don't like it." He also points out that the side button's position changes as you rotate the phone between postures, which matters on a device you hold several ways.

The smaller losses are about attention. 9to5Mac notes that without Face ID, iPhone Duo also loses Attention Aware features such as notifications expanding when you glance at the screen.

Apple Pay, passkeys and passwords

On paper, Touch ID covers the payment and sign-in jobs. Apple's spec page covers Apple Pay in stores, in apps and on the web, and Apple's passkeys guide says Face ID or Touch ID can authorize use of a passkey.

Apple Watch unlock helps less than it sounds. MacRumors confirms you can opt to have an Apple Watch unlock iPhone Duo, but Britta O'Boyle, writing for Macworld and Tech Advisor, says you still need your fingerprint for Apple Pay and saved passwords. Jason Cross makes the same point about approving purchases and downloads.

Cases and the side button

We haven't found an established outlet reporting a specific iPhone Duo case that blocks the Touch ID sensor. If you're shopping, check that a case leaves the side button exposed; the iPhone Duo case roundup is a starting point.

Bottom line: reliable, just not effortless

Based on the reviews, Touch ID on iPhone Duo works, works open or closed, and covers Apple Pay and passkeys. The trade-off is friction: a deliberate press, a short pause, gloves off, and a button that moves with the posture.

If you already wear an Apple Watch, the unlock part mostly fades, though Apple Pay and passwords still need a finger. If you're deeply attached to Face ID, this is the adjustment to weigh most before spending on iPhone Duo. For anyone setting one up, enroll more than one finger: Tech Advisor recommends several because your grip changes open and shut, and a tip MacRumors reported from an owner on Reddit suggests enrolling the lowest part of your index finger. The Touch ID setup guide walks through it, and the launch reviews roundup covers the rest of the phone.

Has Touch ID grown on you, or do you still reach for Face ID? We'll update this guide if Apple changes the unlock behavior in a software update.