OnePlus has only recently announced an upgrade to its OnePlus 3 in the form of the OnePlus 3T, but that won't stop speculation starting for the next "flagship killer".

Rumours are starting to appear, along with predictions from fans as to what we might see on the next OnePlus smartphone. With that in mind, here is a run down of everything we've heard so far and what we want to see.

  • Could be OnePlus 5 instead of OnePlus 4
  • Number 4 is bad luck in Asia

The next OnePlus smartphone should be called the OnePlus 4 and if it was any other number, this probably wouldn't even be called into question. But it isn't any other number because the number four is considered unlucky in Asia, apparently.

If OnePlus does avoid the four, the next OnePlus smartphone could be called the OnePlus 5 instead.

  • May or June release expected

OnePlus revealed the OnePlus 3 on 14 June 2016, the OnePlus 2 on 28 July the year before and the original OnePlus on 23 April 2014, meaning there isn't a distinct release pattern for OnePlus like there is with the Apple and Samsung.

The OnePlus 3T was revealed almost exactly five months after the OnePlus 3 on 15 November 2016 but we wouldn't expect to see another device for six months, allowing the Chinese company to see what the flagships it's trying to kill have up their sleeves.

With Samsung, LG and Sony all likely to announce at Mobile World Congress in early March, we'd expect OnePlus to reveal its offering around June again. It's anyone's guess at the moment though.

  • All glass design suggested
  • Dual camera setup on rear claimed

The OnePlus 3 upped its game in terms of build quality, delivering a premium, solid and metal casing that allowed it to challenge phones £300 more expensive. A fingerprint sensor is positioned on the front, a large rear camera is present on the rear and USB Type-C sits at the bottom.

There has been a suggestion on Weibo that the OnePlus 4 will offer a glass-made body however, which is something the company dabbled with previously on the OnePlus X. Samsung also uses a combination of glass and metal for its current Galaxy S7 and S7 edge, and Google added a glass element to its Pixel smartphones too so it's not an unreasonable suggestion that OnePlus might opt for that route next year instead of all metal again.

A dual-camera setup has also been thrown about, which is plausible too given LG, Huawei and Apple all offer dual cameras on their flagship smartphones and Samsung is rumoured to be adding it to the Galaxy S8.

  • Size reduction to 5.3-inches suggested
  • Resolution increase to Quad HD claimed

The OnePlus 3 and OnePlus 3T both feature a 5.5-inch display sporting a Full HD resolution, as does the OnePlus 2. The OnePlus 2 has an LCD screen, while the two newer models have Optic AMOLED, but all three have a pixel density of 401ppi. 

It is thought the OnePlus 4 might reduce the screen size to 5.3-inches, which will put it between the OnePlus 3T and the OnePlus X in terms of size. It has also been suggested the resolution will increase to Quad HD, which will result in a pixel density of 554ppi.

Apart from Sony Mobile, almost all the flagship smartphones the OnePlus goes up against feature a 2K display so despite the OnePlus 3 delivering a fabulous display, this is the area where the OnePlus devices lose marks in terms of the numbers.

Whether its noticeable to the human eye or not is another story entirely, but if OnePlus wants to remain a flagship killer, an increase in resolution is probably essential, especially given there are rumours of more 4K displays for next year.

  • Dual-camera for augmented reality touted
  • Larger pixels or wider aperture possibilities

A dual-camera setup has been suggested for the OnePlus 4. Several companies have already taken this path, all of which use different technologies in order to deliver different features. Huawei has an RGB and a monochrome sensor for example, while LG has a standard lens and a wide-angle lens.

It has been claimed the two cameras on the rear of the OnePlus 4 might be used for a type of augmented reality or mixed reality feature, which would add yet another feature variation of the dual camera setup. This could be just fans hoping however so take this with a pinch of salt for now.

In terms of camera resolutions, there have been no rumours as yet, but the OnePlus 3T has a 16-megapixel sensor on both the front and rear, so we'd expect the new device to offer the same or similar. There might be an increase in pixel size to match the likes of the Pixel and Pixel XL, or perhaps a wider aperture will be introduced like Samsung did with the S7 and S7 edge.

  • Qualcomm SD830 or SD835 chip suggested
  • 6GB or 8GB RAM, 128GB storage
  • 4000mAh battery capacity rumoured

Claims suggest the OnePlus 4 could feature a Qualcomm Snapdragon 830 or 835 processor, along with 6GB or 8GB of RAM and 128GB of storage. The SD835 chip is due in 2017 and it will come with Quick Charge 4.0, but Qualcomm hasn't detailed exactly when the chip will be ready as yet. It might be that it isn't in available time for the OnePlus 4 and we end up with two devices next year as well, or maybe OnePlus will hold off until it is.

As for the RAM and storage suggestions, both seem plausible. The current OnePlus 3T has 6GB of RAM and 64GB or 128GB storage options so they aren't numbers we haven't seen before. An increase to 8GB of RAM would most likely see OnePlus win points on the numbers chart against competitors and if it is going down some sort of augmented reality route with its rear camera, it will probably need it.

A 4000mAh battery capacity has also been suggested, which would be pretty significant for a device of its purported size. The OnePlus 3T currently offers a 3400mAh battery. 

  • OxygenOS likely, probably based on Android Nougat

The OnePlus 4 will most likely launch on OxygenOS, like its predecessor, but the software is likely to be a customised version of Android Nougat by then, rather than Android Marshmallow, as the OnePlus 3T arrives on.

What features will come with that have yet to be seen, but we'd expect a similar experience to what is already offered to OnePlus 3T users, such as the Shelf, dark and light themes and an enhanced doze mode. There is also an update incoming that will allow users to take longer, expanded screenshots, so we'd fully expect to see that on the new device too.

For now, the OnePlus 4 or OnePlus 5 as it could well be called, is based entirely on guess work. More rumours and leaks will no doubt appear over the coming months however, all of which could help shape a picture of what we might see appear.

Don't expect anything concrete until late Spring, early Summer, but watch this space and we will continue to bring you the latest speculation as it appears.