Discover how to measure it, change it and more with our complete guide.
Our Guide to PPI (Pixels per Inch) and Pixel Density.
In digital photography and design, striking the right balance between image size and image resolution is essential.
Expand a low-res image too large and it will become grainy and pixelated. On the other hand, a great quality image in too small a size will take an age to load — and its detail will be lost on the viewer.
Enter the pixel/inch ratio — a key factor in making your digital images the best they can be. In this guide, we’ll talk about why pixels per inch is important, and how you can measure and adjust it.
What is PPI resolution?
Pixels per inch (PPI) refers to the number of pixels contained within each inch of a digital image. It also refers to the set number of pixels a screen can display.
Generally speaking, the higher the PPI, the better the image quality.
- Lower resolution images contain larger pixels in fewer numbers. This creates a blocky, granular effect — hence the term ‘pixelated’.
- Higher resolution levels benefit from greater numbers of smaller pixels. These create depth, clarity and smoothness.
How does PPI differ from DPI?
DPI (dots per inch) is similar to PPI, but is typically used in print media. Instead of measuring pixels, it measures physical dots of cyan, yellow, magenta and key (CYMK) ink on a printed image. Like pixels, these tiny dots are visible if you zoom in far enough.
You can think of DPI as the print output, and PPI as the digital input.
High DPI generally corresponds with greater detail and quality — just like PPI.
Learn more in our complete guide — DPI explained.
How to find the PPI of an image.
Finding the PPI of an image involves a simple equation:
- Number of pixels ÷ size of the image in inches = pixels per inch
However, many digital images contain PPI details in their metadata. You can find this using native computer programs, or using software such as Adobe Photoshop.
How to find pixels per inch on Windows.
- First, locate your image on File Explorer, or on your desktop.
- Next, right-click the image and select Properties.
- Head to the Details tab to find the resolution.
Alternatively, you can open the file using Windows Photos.
- Double-click your image to open the file.
- Click the three dots at the top of the screen.
- Scroll down to File Info.
- You’ll find DPI/PPI details under the Size Info heading.
How to find pixels per inch on Mac.
- Open the Finder app in the toolbar.
- Navigate to your file.
- Right-click the file and select Open with>Preview.
- Click Tools>Show Inspector.
- Get your PPI details from the display list.
How to find pixels per inch on Photoshop.
- Open your image in Photoshop.
- Click Image>Image Size and open the dialogue box.
- Get the PPI from the Resolution field. You can also use this to decrease or increase the PPI.
How many pixels per inch do I need?
Optimal PPI depends entirely on the size and purpose of your image. As a rule of thumb, if you’re displaying an image on a website, you’ll need a far lower PPI resolution level than if you’re printing off a photo.
Here are a few rough PPI measures you can use for your project.
High-res pixels per inch.
High-res displays can handle more PPI on screen than the commonly held 72 PPI standard. If you’re displaying images or film on a large HD monitor, you can afford a far higher PPI level than your average laptop.
- A high pixel density can range between 100-140 PPI
- A very high pixel density starts off at 140 PPI
Pixels per inch for web.
Web images are often standardised at 72 PPI. Indeed, Adobe Photoshop optimises images at this level for online use.
- The reason is that while vibrant imagery is often key to creating an engaging website or online presence, clarity, richness and detail needs to be balanced with load times.
- The web-optimised 72 PPI level is therefore a good option, as it will allow for both a faster load time and a generally clear and eye-catching appearance.
However, if you’re looking to display higher resolution images for an online art exhibition or digital portfolio, you can go higher.
Just don’t forget to weigh this up against loading times, and bear in mind the resolution capabilities of your display equipment.
Pixels per inch for projections.
Offices, schools and universities make regular use of projections to display large images and presentations. For this, a balanced 102 PPI is often a solid choice.
Pixels per inch for print.
Whether we’re talking nature photography for a glossy magazine, or a direct mail brochure you’ve designed, you’ll need higher pixel density to do the job properly when it comes to the printed page.
- 300 PPI is a go-to option for those looking to produce great print material. This corresponds to the 300 DPI normally required for a high-quality finish from the printer.
- However, you could go lower for non-commercial use, or for smaller designs. 180 PPI and 240 PPI are common choices.
How to change pixels/inches in Photoshop.
You can change the PPI resolution of your image in Adobe Photoshop to suit your media format or purpose. Here’s how to do it.
- Open your image in Photoshop.
- Go to Image>Image Size.
- Deselect the Resample option.
- Enter a new value.
It’s worth noting that this process won’t add pixels to an image that aren’t already in the original file. To do this, you’ll need to resample your image first.
Learn how to do that with our guide to increasing image resolution.
Want to know more about PPI, resampling and resolution? Check out our Image Size and Resolution help page.
Top tips.
- In some applications, confusingly, PPI and DPI are used interchangeably. PPI can refer to print resolutions, and DPI to digital. Unless referring specifically to printing an image (say, on a print preview), DPI probably still means pixels in these cases.
- While pixels per inch can be a useful guide to image quality, some also argue that understanding the full pixel dimensions of the image can offer a better measurement overall.
- Remember to test the performance of higher-res online images, to make sure they don’t slow down your website.
- Try to experiment with lower PPIs for print. If you’re happy with the quality, you can save on ink costs.
Adobe editing tools to check and change image PPI.
- Photoshop. A great option to check and edit PPI, you can also use it for resampling and enhancing your images.
- Lightroom. Combine Photoshop’s editing capabilities with industry-leading project management tools.
- Photoshop Express. Check and edit pixels/inch on the fly with this mobile version of Photoshop.
Pixels per inch: FAQs.
How many pixels per inch is 1920x1080?
A display or image of 1920x1080 pixels is 1080p resolution – commonly known as ‘high definition’. To work out PPI, you’d also need the diagonal measure of the screen or image in inches. Pixel count can then be divided by the number of inches.
Is 72 PPI the same as 300 DPI?
PPI and DPI are different — the first is for digital, the second is for print. 72 pixels per inch is the standard for online use, typically allowing for a smooth loading time and a good quality visual. 300 dots per inch meanwhile is the standard for high-quality print images.
Does higher PPI mean better quality?
Yes, a higher PPI generally correlates with better quality, as the image will have a higher pixel density. However, you’ll also need to take into account the full number of pixels in the image to understand its resolution entirely.