Not sure which iPhone you've got? Here's how to identify an iPhone handset using the model numbers, or based on the physical design
Readers often ask: "Which model of iPhone have I got?" To the uninitiated, most iPhone handsets look pretty similar, and even experienced users can find it hard to tell some of them apart right away.
The easiest way to identify an iPhone is to check the 'A' model number on the back, and in this article we list the A numbers for every iPhone. But if the number is obscured or too small to read, there are other methods: you can use the 'M' model number listed in Settings; or you can look at the phone's shape and external features and make an identification using the descriptions and photos below.
Use the A number on the back
In almost all cases the best way to identify an iPhone is by using the identification number printed on the back. This is a small number that starts with the letter A, and labelled 'Model'. It'll be something like "A1203" or "A1634".
When we say "small number" we really do mean small, and you may find it hard to read the number with the naked eye. A magnifying glass will help if you've got one!
For simplicity's sake we'll call this the A number. (There is also the M or SKU number found in Settings, which we discuss next, and the much longer IMEI identifying number, which is unique to your individual handset.)
Once you've got the A number, check it against this list to see which model you've got. (Note that there are multiple A numbers for some iPhones. These refer to versions for different territories, network standards etc.)
Use the M number (or SKU model number) in Settings
This next technique will provide a more precise identification (including colour and storage capacity), but has the slight down side of requiring that your device be functional and accessible to you. If you're trying to identify a bricked device or one you can't unlock, this won't be much use and you'd better move on to the visual identification chart in the next section.
Open Settings and select General > About. Next to Model you'll see an alphanumeric code almost certainly beginning with an M. (Replacement models will have a number beginning with an N instead.)
We've seen this referred to as the M number or the SKU. Either way it tells you everything you need to know about what sort of iPhone you've got.
There's a huge number of possible M numbers - far more than we can list here. Check the iPhone Wiki for a full list.
Identifying an iPhone by sight
If for whatever reason you can't find or read the M and A numbers (if the device won't switch on and the numbers on the back are too small to read, say), don't worry. You can still tell which kind of iPhone you've got by checking its build, external features and so on. Simply compare it against this guide.
The original iPhone is easy to identify. It has a grey/silver rear with a large black band across the bottom. It looks like this:
iPhone 3G and iPhone 3GS
One way of telling these two apart is colour - if it's white, you've got a 3GS.
Both models were sold in a black finish, however, so if you've got one of those, check the shininess of the detailing on the back. On the 3GS, the Apple logo and the imprint below are the same shiny silver; on the 3G, the imprint is less shiny than the logo.
Be careful not to confuse these two models with the newer iPhone 5c (which looks somewhat similar - see below to compare).
iPhone 4 and iPhone 4s
It's hard to tell the iPhone 4 and iPhone 4s apart, unfortunately. One possibility is to look for a SIM tray on the righthand side - if you can't find an opening then you're looking at (the CDMA version of) the iPhone 4, which was available both with and without a SIM tray. The iPhone 4s always has a SIM tray.
You can also check the storage capacity, which may offer a clue. The 4 was sold in 8, 16 and 32GB capacities; the 4s was available in all of these but also added a 64GB model. Check Settings > General > About, and if Capacity is any higher than 32GB then you've got an iPhone 4s. (It won't be the full 64GB, of course, because some of the advertised capacity is taken up with firmware and the like.)
The iPhone 5 looks similar to the iPhone 4 and 4s but comes with a taller 4-inch display (measured diagonally, corner to corner). This means it can fit five rows of app icons (plus a sixth, the dock row, at the bottom), whereas the iPhone 4s and earlier could only fit four rows (plus the dock). Here's what it looks like:
The iPhone 5s looks largely identical to the iPhone 5, but the giveaway is the Touch ID fingerprint scanner.
If you look at the Home button, you'll notice that it no longer has a square on it - it's just a plain circle. On the white-front models you can see a shiny metal ring around the edge; the black one is entirely black.
The colour schemes are also different, with Gold, Silver and Space Grey replacing Black and White.
This one's easy to spot. The iPhone 5c comes in a range of bright plastic colours and has a curved plastic back.
It's also taller and squarer than other plastic models (such as the iPhone 3G and 3GS), so it's easy to identify.
iPhone 6 and iPhone 6s
The 6-generation handsets saw a full redesign, with rounded-off edges replacing the squarer look of previous phones. The screens are larger than earlier models, too: they measure 4.7 inches diagonally. The Plus models have still larger screens, of course.
Assuming you're not lucky enough to be looking at a pink (technically Rose Gold) model, which is a dead giveaway, look for the letter S on the back, below the word iPhone. (It's visible in the image above.) This indicates that it's an iPhone 6s, fairly obviously.
iPhone 6 Plus and iPhone 6s Plus
The iPhone 6 Plus and iPhone 6s Plus look like the iPhone 6 but are much larger, with 5.5-inch displays (measured diagonally). They've got room for six rows of icons on the Home screen, plus the dock row.
Again, only the 6s Plus comes in Rose Gold, and the S model is designated by a letter S on the back, below the word iPhone.
The iPhone SE uses the same colour scheme as the iPhone 6 product line, but has the same design elements of the iPhone 5s. Your best bet to identify between a 5s and SE is to turn the iPhone on or look for the SE stamp at the back.
It should also be noted that the SE comes in Rose Gold, whereas the 5s only came in Silver, Space Grey and Gold.
The iPhone 7 boasts a 4.7-inch screen, with a glass front and aluminium back. It's similar to the 6 and 6s, but slimmer, and the back of the body has lost the horizontal lines at the top and bottom. Oh, and the camera protrudes slightly from the case, rather than being flush to the body.
iPhone 7 Plus
The iPhone 7 Plus is unsurprisingly similar to the iPhone 7 - the main difference is the larger 5.5-inch display. As with the 7, it boasts a glass front and metal back, which the camera protrudes from slightly. It's also available in six different colours, including red (not shown below).
In fact, the real giveaway is the twin-lens rear-facing camera: here's what it looks like: