Foldable iPhone's Touch ID Sensor Won't Go Under The Display, Insider Says

The iPhone will undergo a massive transformation in the next three generations, according to the most recent reports. The iPhone 17 series, out next week, will introduce the ultra-thin iPhone 17 Air model. Next year's iPhone 18 series will feature Apple's first foldable iPhone, or the iPhone 18 Fold. Then, the 2027 iPhone series will feature Apple's all-glass iPhone 20 model that will mark the iPhone's 20th anniversary. The iPhone 17 Air is the only certainty of the three at the time of this writing, with Apple expected to unveil the ultra-thin model in a few days.

While rumors seem to disagree on Apple's manufacturing plans for the iPhone 20, the iPhone 18 Fold is likely to be unveiled in September 2026. We've seen plenty of rumors this year indicating that Apple has decided to launch its first foldable alongside other iPhone 18 family members in 2026. Reports from various sources also seem to tell the same story. The iPhone 18 Fold display will have a minimal crease in the middle thanks to Apple's screen innovations and willingness to outspend rivals. The ultra-thin foldable will feature two cameras on the back, and a starting price around $2,000.

Interestingly, the first foldable iPhone should bring Touch ID back to the iPhone. That's the fingerprint-sensing tech that Apple removed from the iPhone in 2017 when it introduced the all-screen iPhone X. Analyst Ming-Chi Kuo first mentioned the iPhone 18 Fold's Touch ID sensor in March. On Monday, the analyst doubled down on Touch ID's return, explaining that Apple will likely adopt the same approach most competitors have implemented. The Touch ID button will be placed on the side rather than under the display.

The well-connected insider addressed recent rumors that Apple might go for under-display fingerprint-sensing technology in the iPhone 18 Fold. "Six months ago, I predicted the foldable iPhone would use side-button Touch ID," Kuo said on X. "There are now market rumors that it will adopt an under-display ultrasonic fingerprint sensor, but I think that's unlikely. It's expected that Luxshare ICT will supply the side-button Touch ID module for the foldable iPhone."

Most foldable phone vendors release devices with side-mounted fingerprint sensors like the one Kuo mentions. The advantage of a side button that can scan fingerprints concerns usability. You can unlock the screen and log into apps regardless of how you use the phone. The fingerprint sensor works when the phone is folded and unfolded.

Six months ago, I predicted the foldable iPhone would use side-button Touch ID. There are now market rumors that it will adopt an under-display ultrasonic fingerprint sensor, but I think that's unlikely. It's expected that Luxshare ICT will supply the side-button Touch ID module... https://t.co/KsGu49JXkP

— 郭明錤 (Ming-Chi Kuo) (@mingchikuo) September 1, 2025

Chinese vendor Vivo is the only exception. Some of its foldables feature optical under-display fingerprint sensors. The Vivo X Fold 3 Pro has two of them, one under the external cover screen and one under the foldable panel. You need two identical components to make authentication possible in both unfolded and folded modes. One of the immediate downsides concerns battery capacity, as Vivo has to use internal space to accommodate the sensors. Also, under-display ultrasonic fingerprint sensors might not always work correctly, even if they're more reliable than optical ones.

Despite patents showing its interest in placing Touch ID sensors under the iPhone display, Apple has never released products with such technology. Apple does have products with side-mounted Touch ID sensors, including the iPad mini (image above) and iPad Air. Put differently, Apple already has the technology it needs to make Touch ID happen on a foldable phone without investing in new tech that might drive up manufacturing costs.

Face ID is a signature iPhone feature. All iPhone models Apple sells in stores feature 3D face recognition technology, which the all-screen iPhone X introduced. Apple used Face ID on iPad Pro models in recent years, but not MacBooks. Laptop lids, where Face ID tech would go, are too thin for the Face ID sensors. Device thickness might be the reason why Apple skips placing a Face ID sensor in the iPhone 18 Fold.

The M4 iPad Pro has a 5.3 mm profile and comes with a Face ID sensor. This might give us an idea of the minimum thickness an iPhone or iPad has to have for Apple to include Face ID components in the frame. The iPhone 17 Air should be just 5.5 mm thick, and therefore support Face ID.

Apple's first foldable iPhone would have to be at least 5.3 mm thick for Face ID to happen. In such a scenario, the iPhone would measure 10.6 mm when folded, which is simply too thick by current standards. This year's Honor Magic V5 and Galaxy Z Fold 7 measure just under 9 mm when folded. Unfolded, they measure around 4.2 mm. Rumors say Apple's first foldable phone will be very thin. With all that in mind, Face ID seems out of the question unless Apple can shrink its components significantly.

There's another reason why Face ID isn't as practical on a foldable iPhone. Apple would have to place a sensor in the outer display and one in the foldable screen so authentication works regardless of how you use the handset. This would consume additional space inside the phone, potentially impacting battery life. It's the same as using two ultrasonic under-display Touch ID sensors in the foldable iPhone.