Image showing a close-up shot of a screen, revealing the pixels and pixel density.

Understanding the Concept of Pixel Density: An Ultimate Guide

We already live in the digital age. Screens are everywhere. From our smartphones to television screens, display technology plays an important role in everything that we do today. Our main way of consuming media and accessing information is mostly through smart devices. With the rising popularity of AI, many users are starting to integrate workflows digitally. In order to enjoy screen time, one must have clear and high-quality screens, and that is highly dependent on pixel density.

But how do we define and understand the concept of pixel density, and why is it crucial to know about this term? Why is it relevant today? Should normal consumers be concerned about it? This comprehensive guide will discuss pixel density’s meaning, explaining its significance, how it works, and its impact on our daily digital interactions. Let’s dive in.

Defining Pixel Density

Do you recall people saying, “This image looks pixelated”? When they say that, the image looks either blurry or unclear. This means that you cannot see the details of the image, whether it is viewed near or far. If you have photo editing software with you, like Adobe Photoshop, try opening an image and zooming in to the maximum percentage.

What do you see? If you’re seeing squares with individual colors, each square is actually a pixel. Each pixel holds a single color that may vary from another pixel. Individually, it looks like nothing from the final image. But as you look at the bigger image rather than individual pixels, you see the whole picture. The pixels disappear and you get a good image.

Hence, we can say that pixel density is the measure of how many individual pixels are packed into one inch of the display. The higher the pixel density, the more pixels are used to display images, resulting in sharper, more detailed visuals.

How Pixel Density Works

Image of a scenery showing a partly pixelated portion that vividly shows how pixel density works.
Comparison of Low (left side) vs High (right side) Pixel Density

The concept of pixel density requires more explanation than our simple analogy in the previous section. To understand pixel density, knowing a bit about pixels and resolution is essential.

  • Pixels: Pixels are like tiny dots. They’re just dots but they are the base foundations of an image. In our analogy, the squares are the pixels. If you have more squares, you get more space for colors to fit in. Each pixel holds a specific color only. But each pixel may have a different hue from the other, which creates gradients as we know it.
  • Resolution: Resolution, on the other hand, is the number of pixels presented in width × height format. We describe it as 1920×1080 for full HD displays. You often see this when buying monitors, televisions, and other screens. Nowadays, 1920×1080 is the standard. If you’re getting a screen that’s only 720p, you’re not getting the best viewing and reading experience for your device. While resolution indicates the total number of pixels, it doesn’t provide information about how tightly these pixels are packed together.

Pixel density bridges this gap by indicating how many pixels fit into a given area. Another way to think of pixel density is to relate it to the human population. If there are many people living in a small land area, we can say that the place is “densely populated.” The same thing goes with pixel density. If there are a lot of pixels in a one-inch space, it means that the image has high pixel density.

However, pixel density is not the ultimate factor used when deciding what screen to buy. It’s possible that devices may differ in pixel densities but not deliver the expected output from them. For instance, screen sizes heavily affect pixel density. Smaller screens can pack in more pixels than large screens. Hence, image output may look different across different screen sizes.

Pixels Per Inch or PPI

You’ve probably heard of PPI already. However, it is not really easy to understand its concept if we don’t lay it out here. So, let’s say you have a grid of squares. Each square in the grid measures 1 cm on both sides. Let’s do a little bit of math here. 

In a one-inch space, we fit 2.54 1×1 squares. If we convert the one-inch area to a square, it can fit 6.54 1×1 squares in the space inside it. Now, let’s say the square size has changed to 0.5 cm on both sides. In a one-inch space, you can fit 5.08 squares with a 0.5×0.5. If we make it a one-inch box, it can fit 25.8 squares. 

Do you see where we’re getting here? If your square is smaller, you get to fit in more squares in a one-inch area. But if it’s bigger, you only get to fit in a few. That’s how pixel-per-inch or PPI works. More pixels mean a higher file size. So if you want to keep file sizes minimal, adjusting the PPI to an acceptable level is needed.

So, with our simple analogy with squares, I hope you understand the PPI concept. In the next sections, we’ll dive into more technical terms and we hope that you already got the concept of pixels and PPI. 

Importance of Pixel Density

Pixel density plays an important role in the overall user experience, especially in smartphones and computers. It is also important for artists and illustrators because pixel density heavily affects the final output of their work. Overall, here are the three reasons why pixel density is important.

  1. Text Sharpness: Higher pixel density ensures that the text appears crisp and legible when reading text on screens. If pixel density is low, the eyes will have a hard time seeing the text on the screen. It will cause eye strain and fatigue to the eyes. Text sharpness also affects how you perceive images on the screen. Blurred images may not look what they seem to be. Hence, text sharpness is vital for pixel density.
  2. Image Clarity: An image will be clear if the screen has enough pixels to project it without compromising quality. However, we don’t believe that it’s true in all aspects. Artists and graphic designers will pay more attention to this. That’s why creatives buy expensive monitors with high pixel densities and excellent picture quality. This is particularly important for high-definition displays where fine details matter, such as in photography, video production, and gaming. Since their work requires color and detail precision, creatives need to have good pixel density.
  3. Visual Comfort: Higher pixel density contributes to smoother visuals and minimizes the appearance of uneven edges and pixelation. Nowadays, most smart devices have decent pixel densities on average. If you’re the type of user who only uses smart devices for consuming content like videos, music, and text, a device with the optimal pixel density is ideal. This enhances the overall viewing experience, making it more comfortable for prolonged use. But if you’re creative, significant investment is required because devices with higher pixel densities often come at an expensive price.

Pixel Density Throughout History

Pixel density has evolved significantly over the past few decades. What was clear to you ten years ago doesn’t look clear now. For instance, a monitor from 10 years ago won’t look as sharp and crisp as a monitor from today. The same thing goes for smartphones. If you compare the first-generation iPhone to the recent iPhone 15, the screen has drastically improved. 

Technological advancements and consumer demand enabled companies to manufacture screens that produce sharper and more detailed pictures. In our opinion, many companies will continue to push the boundaries of technology and make screens even better until we reach the point that screens will almost feel like real-life objects and sceneries. Let’s explore the key milestones in the evolution of pixel density and how this technology evolved throughout history.

Early Displays

Back when computers were still new, displays were limited in terms of resolution and pixel density. But for the people back then, those displays look stunning already. For them, it already produced the best image quality. The famous screen technology that time would be CRT monitors and screens or cathode ray tubes. If you remember those monitors and televisions with a large back portion, those devices are CRTs.

A CRT monitor has a resolution of 640×480. For basic tasks, it’s already perfect. How about for gaming? Well, we can say that it was also optimal. Games back then still didn’t feature a lot of 3D effects and rendering, so the quality of CRT monitors was not an issue. But for instance, if you play GTA 5 on a CRT monitor, the image quality will be a disaster!

The Transition to LCD

CRT monitors were in it for years, from the 1980s to the 1990s. But during the 90s, people were wondering if displays could be slimmer and clearer. Hence, liquid crystal displays, or LCDs, were born in the late 1990s. Unlike CRTs, LCDs were slimmer and wider. Trimming the excess size also paved the way for larger screens due to their lesser weight.

But with new technology entering the market, LCDs back in the early 2000s were expensive. CRTs are still fighting for survival back then and they are already top picks for those who can’t afford LCDs. The resolution of a LCDs in the early 2000s were 1024×768, which is better than CRTs. 

The Rise of High-Definition

Technology gives birth to technology indeed. The old ones paves the way for newer ones to step in. And with the popularity of LCDs came the rise of high definition displays or HD. This type of display still uses LCD technology but it only features higher resolutions at 1280×720 and 1920×1080. This was late 2000s already and LED screens are relatively young in the screen display market.

We could say that the late 2000s is the era of LCDs. This era saw a significant increase in pixel density, especially in televisions and computer monitors, leading to sharper images and better viewing experiences. Gone are the days of CRT. 

However, LCD had an expiration date because LEDs are starting to emerge. As said previously, old tech gives birth to new tech. With LCDs boasting HD quality, LEDs will catch up soon enough in the screen industry.

Retina and High PPI Displays

Displays keep getting better and better. But surprisingly, people seem to want these displays in smaller devices as well. They just don’t want their televisions to have good displays but also prefer that these outstanding displays be included on their phones. And in 2010, Apple shocked the world with its Retina Display. During this time, the iPhone 4 has the best display of all phones back then.

It features a pixel density of 326 PPI, which is five years in advance of its time. Apple’s Retina Display is considered a tech marvel that should’ve existed only in the next five years. Hence, this paved the way for the production of better smartphone screens. Before Apple’s release of the Retina Display, most phones had visible pixels on the screen. People didn’t mind it back then. But when they were introduced to Retina, perceptions changed, and the consumer technology market seemed to want more quality.

4K and Ultra HD

The rise of 4K displays didn’t take that long. If we compare it to the gap between CRTs and LCDs, transitioning to 4K displays only took less than five years. The rising popularity of 4K Ultra High Definition (UHD) displays in the early 2010s pushed pixel density to new heights. Upon initial introduction, it’s still a bit pricey given that it’s new technology. But that’s just how the cycle goes, right?

A 4K display boasts a resolution of 3840 x 2160. If we compare that to full HD, we’re getting better images with 4K displays because it’s four times better than 1920×1080. Game developers also started to ramp up their games. That’s why 4K displays are continuously rising; games have already caught up with the latest tech in the market. With 4K displays in the market, pixel densities rose to over 160 PPI on larger screens. The increased pixel density of 4K displays enhanced image clarity, making them ideal for tasks that require fine detail, such as graphic design and video editing.

The Rise of 8K

As soon as 8K hits the majority of the consumer market, it’s possible that HD will meet its demise. Nowadays, 8K displays aren’t accessible to the general consumers because of its price. The prices of 4K displays are still expensive but it’s slowly penetrating the general tech consumers. And once 8K becomes less expensive, it’s possible that standard HD displays will be phased out and full HD will be the new lowest standard.

An 8K display boasts a resolution of 7680 × 4320 pixels. This resolution is already at the peak of today’s screen technology. These displays offer pixel densities of over 300 PPI on large screens. This level of PPI makes displays so realistic and detailed, as if you’re looking at a real object. While 8K content is still emerging, the technology showcases the potential for future advancements in display quality.

Looking Into the Future

While the story of displays throughout history sounds like a Star Wars saga, it is expected that displays will keep on getting better. If a 4K display is considered luxury today, it might not be in the future. What’s next to 8K? Will there be 16K? Are we looking at 3D displays and holographic displays in the future? Are we deviating from 2D screens and venturing into augmented reality, mixed reality, or virtual reality? We never know.

Pixel Density Calculator

If you don’t like math, please bear with us for a bit. We’ll try to explain this as simple as possible. Knowing how to calculate pixel density can help you in making decisions about screen resolutions and quality.

The formula to calculate pixel density (PPI) is:

PPI is equal to the square root of the sum of W2 and H2 divided by D. The variables are explained below:

  • W is the width of the display in pixels
  • H is the height of the display in pixels
  • D is the diagonal size of the display in inches

The PPI formula uses the Pythagorean theorem to determine the diagonal pixel resolution and then divides it by the screen’s diagonal size to find the PPI. Let’s break this down into easier chunks.

For illustration purposes, Let’s assume that our screen display product features a resolution of 1920×1080 or Full HD. The size of the screen is only 13 inches. Let’s compute the PPI.

1) Determine the Square of W and H

It’s fairly easy to determine the square of both. Since screen resolutions are always width times height, our W is 1920 pixels, and H is 1080. Grab your calculator, and let’s compute.

  • W2 = W x W = 1920 x 1920 = 3,686,400
  • H2 = H x H = 1080 x 1080 = 1,166,400

Take note of these numbers.

2) Get the Square Root of the Sum of W2 and H2

First, let’s get the sum of squares. The sum would be 4,852,800. The square root of 4,852,800 is 2,202.91 pixels. This number is the numerator in our formula, and it is also called diagonal pixels. It means that 2,202.91 is the number of pixels along a straight diagonal line.

3) Divide the Square Root by D

Now, let’s divide 2,202.91 by 13 inches. Our PPI is equal to 169.45 pixels per inch. What does this mean? It means that per inch of screen, there are approximately 169.45 pixels. As your screen size goes, the PPI decreases. For instance, what if the screen is 27 inches? The PPI is now equal to 74.88 pixels per inch.

The Ideal PPI for Each Type of Device

DevicePPI Range
SmartphonesAt least 300, but higher is better (up to 500)
LaptopsAt least 180, but higher is better (up to 300)
TabletsAt least 150, but higher is better (up to 350)
MonitorsAt least 100, but higher is better (up to 200)
TelevisionsAt least 50, but higher is better (up to 100)
VR HeadsetsMore than 600

The pixel densities also vary depending on the viewing distance. For example, monitors don’t require high pixel density because the typical viewing distance is 20 to 30 inches away from the screen. Now if compared to smartphone which is viewed 10-12 inches away, the pixel density is high.

Why is that? It’s because as you look closer at the screen, it’s possible to see the individual pixels. Hence, televisions don’t have high PPI because you won’t be able to place a TV a few inches away from your face, right? Kidding aside, this table above only proves that a higher number is not always better. It’s best to look at the type of device first before deciding.

Factors Affecting Pixel Density

Several factors affect pixel density. The PPI is not a fixed number that you can just use as the sole basis of picture quality. PPI is merely one of the several factors that you need to consider. It’s not the ultimate factor, so to speak. Understanding the factors affecting pixel density helps in appreciating how different devices achieve their unique display characteristics.

Screen Size and Viewing Distance

The physical size and intended viewing distance of a screen play a significant role in determining pixel density. As discussed earlier, screen sizes affect pixel density because of the area it needs to fill. If there is little screen space, pixels are more compact. Conversely, a screen with a large space to fill in needs more pixels to deliver the best image. Hence, the resolution must also adjust as screen sizes get bigger.

The viewing distance also affects pixel density in conjunction with its size. For smartphone, users are expected to use it 10 to 12 inches away. It’s closer so a higher pixel density is needed to prevent pixelated views. Whereas a television, that’s meant to be viewed 20 to 30 inches away, will have lower pixel density since people won’t be too closed up in the screen.

Our Expert Opinion: We believe that high PPI is needed for devices held close to the eyes, such as smartphones and VR headsets. Always look at PPI when buying devices. Don’t just buy because it’s on sale or at a promo price.

Resolution

The screen resolution also dictates the total number of pixels in the screen. For example, a 1920×1080 resolution is equivalent to 2,073,600 pixels. However, in relation to screen size, resolutions must respond proportionately. As you increase in screen size, the resolutions must increase as well. If the resolution is lower, the picture quality may look less sharp.

Our Expert Opinion: We believe that higher resolutions are only needed for professional creative work like graphic design and video editing. They also enhance the viewing experience for high-definition content. However, for daily consumption and reading, the full HD resolution is optimal.

Display Technology

The kind of screen also affects pixel density. Display technologies like OLED or MicroLED vary in how pixels are packed in together. You have to consider beforehand what kind of screen technology you need in order to assess pixel density. For instance, OLED displays reaches higher PPI compared to LCDs because they do not require backlighting.

Our Expert Opinion: LED is currently the best display technology for anything screen-related. It is in our expert opinion to say that investing in LED screens will be worth it for the years to come. Moreover, choosing advanced display technologies like OLED and MicroLED can benefit professional creatives because these products offer better color accuracy and contrast.

Type of Content

Different kinds of content differ in quality. Images and videos can be standard definition (SD), high definition (HD), Full HD, Ultra HD, 4K, and even 8K. The kind of content you’re consuming affects the kind of screen you need.  Graphic designing, illustrating, and video editing require higher PPI for optimal viewing. While productivity tasks like reading, checking emails, or watching YouTube don’t require very high PPI.

Our Expert Opinion: We highly recommend that you first take a step back and determine your primary use of the device. It will help you choose a device that suits your needs, lifestyle, and career.

Pixel Density in Relation to Other Factors

While high pixel density is desirable, it is not the only factor that determines the quality of a display. As discussed previously, pixel density is just one of the factors that you should consider. It’s not the sole factor that should drive your decision. Hence, here are some considerations that you might want to know in relation to pixel density.

  • The color of the screen will affect pixel density if it’s not accurate. Having more pixels won’t fix inaccurate colors. It’s best to color correct your screen using a special software.
  • Screen brightness helps your eyes see things on the screen. It doesn’t fix blurred images and text due to low pixel density.
  • Screen refresh rates can ruin your experience if you have a high pixel density screen. There must be a balance between refresh rate and pixel density to avoid motion blur.
  • Screens with good pixel density, resolution, refresh rates, and other features come at an expensive price. Expect to pay a premium for having these features.

Conclusion

In conclusion, pixel density is a crucial factor in displays. It is something that professional and casual users should take note of when buying a product. Whether you’re using a smartphone, laptop, or smart television, pixel density dictates the ultimate viewing experience. However, you should remember that while pixel density heavily influences quality, other factors exist, such as display technology and content variety. In making a buying decision, we highly encourage you to weigh all factors and consider all other options available. We hope this article helped you understand the meaning of pixel density and why it’s important.

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