Touch ID vs Face ID

cutting to the chase:
I am curious why the face id tech cannot accommodate finger print scanning i.e. touch id


oh wait, not eom

I just really find touch id convenient


I’m not sure what the question is.

If you’re asking why Apple doesn’t ship a single device (phone or iPad) with both a FaceID camera and a TouchID sensor, I would say that that’s a business decision. There’s no technical reason why a single device couldn’t have both. It would make the lower bezel of the device bigger, which Apple wants to avoid, but it could definitely be done.

I believe the current iPad Pro models have a TouchID sensor integrated with the sleep/wake button. Apple could probably slip a sensor in there on other devices, but I don’t know how much space it would consume - they might have to make phones larger to accommodate it.

If you’re asking why the FaceID camera can’t scan your fingerprint (put your thumb over the lens?) that’s a different question. Those two technologies are completely different.

While there are optical fingerprint scanners (some door-locks use them), they require a large piece of glass (at least as large as your fingerprint) to place your finger on. Then a camera (focused on that glass) can read your print.

In contrast, the FaceID camera is tiny - far too small to read a fingerprint. If Apple would use a large camera lens (maybe about 2 cm square) then, sure, you could press your finger up against it and probably get a reading. But that would make the phone and its upper bezel much larger - something I suspect Apple doesn’t want to do.

Could it use the rear camera lens? Maybe, but I suspect those lenses can’t focus on something pressed up against the cover-glass. I don’t know how hard it would be to make that work (vs. adding yet another camera to the device).

In comparison, Apple’s TouchID sensors are not optical. They use electrical capacitance to detect what part of your finger is and is not touching the sensor. Think about it as a super-high-res trackpad.

Could that be embedded under a screen (to avoid making the phone bigger)? Maybe. I think some Android phones are doing that, but I don’t know how good it works - you don’t want to sacrifice accuracy for convenience on a security device.

Could they put the touch sensor on the back? No technical reason why not - some Samsung phones have done that, but I assume Apple doesn’t want to, or they would have done it already.


From a purely technical standpoint, there’s no reason I’m aware of that a device couldn’t include both. They’re completely separate sets of hardware, and the only point where the software has to overlap is where it tells the OS that the authentication is verified. They wouldn’t need to conflict with each other.

The reason that no iOS devices actually include both is that Apple has deliberately been trying to get rid of TouchID. The TouchID sensors take up space that Apple would rather use for other things. FaceID’s hardware is special cameras and sensors that (1) take up much less space in a device, and (2) have value for other tasks beyond just FaceID.

That said, I think that the side-button TouchID in many iPads (ones without Home buttons that don’t support FaceID, such as my 4th-gen iPad Air) demonstrates quite well how TouchID doesn’t have to have a bulky Home button on the face of the device, and so could feasibly co-exist with FaceID if Apple wanted to include both. I think a large part of the reason for not including this form of TouchID on iPhones is that most iPhone cases cover the side button, which would prevent TouchID from working. Also, space is much more limited in iPhones than in iPads, and not including the additional hardware for TouchID lets Apple put other things in that space.

There’s also the potential security issue that comes from having multiple ways of unlocking a device. Every available method for unlocking adds a pathway for someone to be coerced into unlocking it. So limiting those options helps keep people from being forced to unlock their device for someone else.

I also prefer TouchID over FaceID. When I finally replaced my old iPhone 7 Plus with a refurb 12 Pro Max earlier this year, it took me several weeks to get used to the different way you have to hold the device when using FaceID compared to TouchID, especially for functions like Apple Pay where the action is confirmed by a double-press of the side button. I don’t normally hold my phone in such a way that the side button is easily pressed (it’s placed too high on the device for that to be routinely comfortable for me), so I always have to adjust my grip. And FaceID is notoriously fussy about the angle you hold the device at for it to recognize you; TouchID doesn’t care about the angle, as long as you’re properly covering the sensor with your fingerprint.

But the biggest reason I prefer TouchID over FaceID is that TouchID is deliberate. If you don’t put your finger on the sensor, there is zero chance of the device authenticating unintentionally. With FaceID, just holding the device where you can look at the screen can trigger FaceID. This is why things like Apple Pay require the additional side-button confirmation, and why unlocking the device requires a swipe up.

But not every FaceID action requires a physical action to confirm it. One such case is that if you have Notification previews when locked turned off, you don’t have to do anything except look at the phone for FaceID to trigger and those previews to show up without any swipe or button presses, making that option almost completely useless.

I’ll admit that since I’ve gotten used to it, I can use FaceID almost as seamlessly as I used to use TouchID. But “almost as” is still short of “equally as”, much less “more than”.


My guess is that it’s because it’s a bigger pita to keep turning your mobile phone around and around to sign in and out. Personally speaking, I think it would be a major PITA to deal with when you are outdoors it’s raining, snowing or icy.

With a fingerprint sensor on the back, you wouldn’t turn the phone around to use it. You use a finger that’s already on that side of the phone. I know a lot of people default to the thumb for TouchID, but you can use any finger you want.

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It might interesting if you could slide your fingertip across a front-facing camera.

@Quantumpanda has it.

The worst consequence of FaceID triggering is usually that it will simply mistake something else for my face and then eventually lock me out for multiple consecutive failures, which is very annoying, although you soon learn to avoid situations where that might happen, or avoid getting anywhere near the frame until you’re sure the device is in position. But it still makes for an objectively worse experience than TouchID ever was. About the only exception to this is when my fingers are wrinkly following a shower, or wet–then, obviously, FaceID has the upper hand. Then there was the brief period during Covid with the whole mask bypass thing. But, honestly, if I could choose, I’d choose to go back. Maybe it’s a rather blindness-specific use case but being able to reach one-handed into your pocket to use your phone is also really handy, particularly if you’re sat on the bog …

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I’ve been using Face ID since it debuted with the iPhone X, and it has been totally fine the entire time. The performance, accuracy, and flexibility (working at more angles) have improved over time, but the only regular issue I have with it is that when I’m using my iPhone without my glasses on, I hold it too close to my face for Face ID to work. If it fails, I just move it a few inches further away (to where I can’t read the screen) and Face ID works fine.

I still use Touch ID on my 10.5-inch iPad Pro and M1 MacBook Air, and while it works fine, I find that I have to think about it a lot more—Face ID just works without me even noticing 95% of the time.

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