DPI vs PPI: What's the Difference and Why It Matters
Two terms that everyone confuses, explained clearly with practical examples for designers, photographers, and developers.
Two terms that everyone confuses, explained clearly with practical examples for designers, photographers, and developers.
Last updated: February 2026
DPI and PPI are two of the most frequently confused terms in digital imaging, and the confusion is not helped by the fact that many software applications, operating systems, and even hardware manufacturers use them interchangeably. But they describe different things, and understanding the difference will save you from costly mistakes, whether you are preparing a photograph for print, designing a website, or choosing a new monitor.
PPI stands for pixels per inch. It describes the density of pixels on a digital screen or within a digital image. A pixel is a single square of color information, and PPI tells you how many of these squares fit into one linear inch. A higher PPI means smaller pixels, which means sharper images and text. Your monitor has a fixed PPI determined by its physical size and native resolution. For example, a 27-inch monitor running at 2560 x 1440 has approximately 109 PPI.
DPI stands for dots per inch. It describes the density of physical ink dots that a printer can deposit on paper. When a printer lays down ink, it creates a pattern of tiny dots that the human eye perceives as a continuous tone image. A higher DPI means the printer can place more dots in each inch, producing finer detail and smoother gradients. A typical consumer inkjet printer operates at 300 to 1200 DPI, while professional photo printers can reach 2400 DPI or higher.
The key difference: pixels are digital and exist on screens. Dots are physical and exist on paper. PPI is about display; DPI is about print output. You can measure your own screen's PPI right now using our PPI Ruler tool.
The terms became tangled for historical reasons. In the early days of personal computing, screens were low resolution, and the concept of "pixels per inch" was not widely discussed outside of engineering circles. When graphic design and desktop publishing took off in the late 1980s and 1990s, DPI was already an established term in the printing industry. As designers began working digitally, they carried the DPI terminology over to screens, even though screens use pixels, not ink dots.
Software companies perpetuated the confusion. Adobe Photoshop's "Image Size" dialog uses "pixels/inch" for image resolution, which is technically correct, but for decades the field was labeled in a way that many users read as "DPI." Windows has a "DPI scaling" setting that has nothing to do with printer dots. It adjusts the size of on-screen elements relative to the display's actual pixel grid. When you set Windows to "150% DPI," you are telling the operating system to render UI elements 1.5 times larger than their default size, a scaling factor that compensates for high-PPI displays where everything would otherwise appear tiny.
Apple's marketing contributed its own term: "Retina display." Rather than quoting PPI numbers, Apple defined Retina as a display where the pixel density is high enough that individual pixels are not discernible at a normal viewing distance. This effectively means PPI above roughly 220 for handheld devices and above 110 for desktop displays at typical distances, but by branding it as "Retina" they sidestepped the DPI/PPI debate entirely.
A monitor's PPI is a fixed physical property. You cannot change it without physically swapping the panel. It is calculated using the formula:
PPI = sqrt(horizontal_pixels^2 + vertical_pixels^2) / diagonal_inches
Here are some common examples:
| Monitor | PPI |
|---|---|
| 24" 1920x1080 | 91.8 |
| 27" 2560x1440 | 108.8 |
| 27" 3840x2160 (4K) | 163.2 |
| 32" 3840x2160 (4K) | 137.7 |
| 13" 2560x1600 (MacBook Air) | 227.0 |
| 6.1" 2556x1179 (iPhone 15) | 460.9 |
Higher PPI means individual pixels are smaller and harder to see, resulting in a sharper, more detailed image. At around 300 PPI at a reading distance of 25 to 30 cm, most people with normal vision can no longer distinguish individual pixels. This is why phones and tablets have PPI values in the 300 to 500+ range: they are held close to the face. Desktop monitors, viewed from 50 to 70 cm away, can get away with lower PPI and still appear sharp.
Digital images also have a PPI value embedded in their metadata. This is the "resolution" setting you see in Photoshop's Image Size dialog. Crucially, this embedded PPI value has no effect whatsoever on how the image appears on screen. A 3000 x 2000 pixel image set to 72 PPI looks identical on a monitor to the same image set to 300 PPI. The pixel dimensions are what matter for screen display. The embedded PPI value only becomes relevant when you print: it tells the print software how large to make the image on paper.
When you send an image to a printer, the software uses the image's embedded PPI value to determine the print size. A 3000 x 2000 pixel image at 300 PPI will print at 10 x 6.67 inches (3000 / 300 = 10 inches wide). The same image at 150 PPI will print at 20 x 13.33 inches. The pixel data is identical; only the physical size on paper changes.
The printer's own DPI capability determines how finely it reproduces each pixel. A pixel in a digital image is a single color value, but reproducing that color on paper requires multiple ink dots of different colors (typically cyan, magenta, yellow, and black, abbreviated CMYK, sometimes with additional light cyan, light magenta, and other inks). A single pixel at 300 PPI might be rendered using a cluster of 8 x 8 or 16 x 16 printer dots, which is why a printer's DPI is often much higher than the image's PPI.
For practical purposes, these are the standard image resolutions for different print outputs:
A common mistake is preparing an image at 72 PPI in Photoshop and expecting it to print well. If the pixel dimensions are sufficient (for instance, 3600 x 2400 pixels), you can simply change the PPI to 300 in the Image Size dialog without resampling, and the image will print at 12 x 8 inches at full quality. The pixel data does not change; only the metadata instructing the printer on print size changes. Problems arise when the pixel dimensions themselves are too low for the desired print size at the needed PPI, resulting in visible pixelation.
Both Windows and macOS use "DPI scaling" (or "display scaling") to adjust the size of user interface elements on high-resolution screens. This is perhaps the single greatest source of DPI/PPI confusion for non-technical users.
On a 27-inch 4K monitor at 163 PPI, running Windows at 100% scaling would make everything extremely small. Text designed to display at a comfortable size on a 96 PPI monitor would appear at roughly 60% of that size on the 4K panel. To compensate, Windows defaults to 150% scaling on such monitors, rendering UI elements 1.5 times larger. The result is that on-screen objects appear at roughly the same physical size as they would on a lower-PPI display, but with sharper edges and finer detail because there are more pixels available to draw them.
macOS handles this differently with its "Retina" approach. On Retina MacBooks and iMacs, macOS doubles the pixel count in each direction (2x scaling). A UI element that measures 100 x 100 logical points is drawn using 200 x 200 physical pixels. This produces extremely crisp rendering at the cost of the effective screen real estate matching a display at half the resolution. A 5K iMac (5120 x 2880 pixels) has the effective workspace of a 2560 x 1440 display, but every element is drawn with four times the pixel detail.
For web developers, DPI scaling manifests as the devicePixelRatio property in JavaScript. A value of 2 means the browser is rendering on a display where each CSS pixel is backed by a 2 x 2 grid of physical pixels. Designers must provide images at 2x or 3x resolution to appear sharp on these high-DPI displays, which is why the srcset attribute and responsive image techniques have become essential. You can check your browser's current pixel ratio and scaling using our @media helper tool.
This is a misconception. Images displayed on the web are rendered pixel-for-pixel by the browser. The DPI/PPI metadata embedded in the file is ignored entirely. A 1200 x 800 image at 72 PPI looks exactly the same on screen as a 1200 x 800 image at 300 PPI. What matters for web use is the pixel dimensions relative to the display area and the device pixel ratio. Saying an image needs to be "300 DPI for the web" is meaningless; what you actually need is an image with enough pixel dimensions to appear sharp at the size it will be displayed, accounting for high-DPI screens.
You might see a phone listed at 460 PPI and a printer at 300 DPI and conclude the phone is "higher resolution" than the printer. But these numbers measure different things and cannot be directly compared. The phone's 460 PPI means 460 individual pixels per inch of screen. The printer's 300 DPI typically refers to the image resolution input, while the actual ink dot resolution might be 2400 DPI or more. Each image pixel is rendered by multiple printer dots. Comparing phone PPI to printer DPI is like comparing miles per hour to kilometers per liter; they measure different properties.
This happens when applications are not designed for DPI scaling. Older or poorly coded applications render their UI at 100% scale and then let the operating system stretch the result, producing a blurry, upscaled image. Modern applications that support "DPI-aware" or "per-monitor DPI-aware" modes render natively at the scaled resolution, producing crisp output. If you encounter blurry applications after changing your DPI scaling, check the application's compatibility settings or look for an update that adds high-DPI support.
If you design for screens: think in pixels, not DPI. Your mockups should be measured in pixel dimensions at 1x scale, with assets exported at 2x and 3x for high-DPI devices. The PPI of your design monitor affects how large things appear to you as you work, but it does not change the pixel values in the file. Working on a 4K monitor means you see a more accurate representation of how the design will look on high-DPI devices, but the design files themselves are resolution-independent in modern tools like Figma and Sketch.
If you design for print: think in physical dimensions and PPI. Design your layout at the final print size (in inches or centimeters) at 300 PPI. This gives you the pixel dimensions you need. A 10 x 8 inch print at 300 PPI requires a 3000 x 2400 pixel image. When sourcing photographs, ensure they meet this pixel dimension requirement. It does not matter what PPI is embedded in the file metadata as long as the pixel count is sufficient.
If you work across both screen and print: maintain your master files at the highest pixel dimensions practical, and export appropriately for each medium. For screen, export at the required pixel dimensions. For print, export at the required physical dimensions at 300 PPI. Our monitor calibration guide will help ensure the colors you see on screen match what comes off the printer. You can also explore how color is handled across devices in our photo editing monitor guide.
To calculate your monitor's PPI manually, you need two pieces of information: the native resolution (e.g., 2560 x 1440) and the diagonal screen size in inches (e.g., 27 inches). Plug these into the formula:
diagonal_pixels = sqrt(2560^2 + 1440^2) = 2937.7 PPI = 2937.7 / 27 = 108.8
For a quicker method, use our PPI Ruler tool, which detects your resolution automatically and lets you enter your screen size to calculate PPI instantly. It also renders a physical ruler on screen that you can hold an actual ruler against to verify the accuracy of your browser's pixel-to-inch mapping.
Knowing your monitor's PPI helps you understand how designs will look at different viewing distances, whether your display is sharp enough for detailed photo editing, and how DPI scaling settings interact with the native resolution. It is one of the most practical numbers to know about your display.
No. PPI (pixels per inch) measures the pixel density of a digital screen or image file. DPI (dots per inch) measures the ink dot density a printer can produce. They are often used interchangeably in casual conversation, but they describe fundamentally different things: pixels on a screen versus physical dots of ink on paper.
At typical desktop viewing distances of 50 to 70 cm, most people perceive text and images as sharp at around 110 PPI or above. Apple's Retina threshold is roughly 220 PPI for devices held at arm's length. For a 27-inch monitor, 1440p (109 PPI) looks good and 4K (163 PPI) looks excellent.
For high-quality photo prints viewed at arm's length, 300 DPI is the standard. For large-format prints viewed from several feet away, 150 to 200 DPI is often sufficient. Billboard and signage printing can go as low as 30 to 72 DPI because they are viewed from a great distance.
No. Your monitor's PPI is a fixed physical property determined by its resolution and screen size. The Windows DPI scaling setting (100%, 125%, 150%, etc.) controls how large UI elements and text are rendered. Increasing the scaling makes things bigger but does not change the number of physical pixels on the panel.
Use the formula: PPI = sqrt(width_pixels^2 + height_pixels^2) / diagonal_inches. For example, a 27-inch 2560 x 1440 monitor has a diagonal pixel count of sqrt(2560^2 + 1440^2) = 2938, divided by 27 = 108.8 PPI. You can calculate this instantly with the DisplayPixels PPI Ruler tool.