Smartphones have been rapidly increasing their megapixel count over the last few years, and now we're at the point where you might find that your phone camera has ten times the resolution of your mirrorless camera, if not more.

So, what's the deal? How are smartphone manufacturers cramming so many pixels into their tiny sensors? It's all to do with something called pixel binning.

In this article, we'll tell you everything you need to know about pixel binning, including what it is, how it works and why it's used. Let's dive in.

What is pixel binning?

To kick things off, we should begin by explaining a little about how camera sensors work. A sensor is divided into millions of tiny light-gathering units called photosites, more commonly referred to as pixels. To get the best results, you typically want these photosites to be as large as possible, as more surface area results in better low-light performance.

Samsung Isocell HP2 Binning
Samsung

The problem with having large pixels is that it's a trade-off, as the larger your pixels are, the less you'll be able to fit on a sensor. No one wants a tiny 2MP image with excellent low-light performance, after all.

That's where pixel binning comes in. Essentially it's the process of using software to combine adjacent pixels to act as a single, larger pixel. The most common type of binning is four-in-one, where four adjacent pixels are combined to act like one big pixel. But, more recently we've seen companies like Samsung implementing nine-in-one and even sixteen-in-one binning on the 200MP Isocell HP2.

There's still the same trade-off, you can use these artificially larger pixels to get better low-light performance, but you'll have a lower-resolution image as a result. Or, without binning, you can have a very high-resolution image, so long as the lighting is sufficient. The difference is that you can now switch between them.

Isocell HP2 Pixel Binning
Samsung

Using the Isocell HP2 camera on the Galaxy S23 Ultra as an example, the phone applies some very clever software magic, and can effectively switch between a low-light optimised 12.5MP sensor, a detailed 50MP sensor for general use, and a 200MP ultra-detailed sensor in optimal lighting scenarios. In theory, it's the best of all worlds.

Why not just use a lower-resolution sensor?

Well, the truth is that you can, and companies like Apple and Google have proved that. Until recently, both companies stuck to their tried and true 12MP sensors on even their top-tier flagship phones - and at the time, they were widely regarded as some of the best smartphone cameras on the market.

Meanwhile, competing brands were engaging in a megapixel-count race with middling results. This might lead you to believe that high-megapixel phone cameras and binning tech is all just marketing hype, and that does factor in, but it's not the whole story.

Apple iPhone 13 Pro to have upgraded ultra wide angle lens with autofocus photo 1

Both the Apple iPhone 14 Pro and iPhone 14 Pro Max, as well as the Google Pixel 7 and 7 Pro feature 50MP(ish) main sensors with pixel binning. So why have they switched?

Well, there are two compelling reasons, in our view. The most important one, right now, is digital zoom. Having extra megapixels means that you can zoom much further while retaining details, and both brands rely on this to get the most from their camera array.

The other is 8K video recording, and while neither brand offers it right now, we're certain that they will on future models. An 8K video is roughly 33.2MP per frame, so you need a pretty high-resolution sensor to capture it. Adopting the hardware early allows these brands to refine their software before releasing it as a feature.

Which phones use pixel binning?

Generally speaking, almost every phone with a camera resolution above 12MP is using pixel binning. So it's simpler to look at the ones that don't, and there aren't many flagships these days that make the list. Some notable models that don't use pixel binning are:

Are there any alternatives to binning?

In the quest for better image fidelity, some manufacturers are looking towards sensor size, rather than image resolution. And we'll likely see these two approaches converge in the near future, with cameras offering both very high resolution and large sensor sizes.

There have been a few phones launching with 1-inch sensors lately, all relying on Sony's IMX989 camera module. This sensor also uses binning but keeps the resolution at a modest 50MP, when compared to Samsung's 200MP snapper.

Sony IMX989 size comparison
Sony

As we learned earlier, larger sensors mean larger photosites, which in turn means better low light. This combined with the 4-in-1 binning means much better low-light performance at a 12MP output, and 50MP shots can be used in less ideal lighting, too.

We've seen this on phones like the Vivo X90 Pro and Xiaomi 13 Pro lately, and we wouldn't be surprised to see it appearing on other flagship devices in the coming year.