PPI Calculator

Calculate the pixel density (PPI) of any display. Enter the horizontal and vertical resolution along with the diagonal screen size.

🔎 PPI & Screen Size Calculator

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💡 Key Takeaway: Pixel density (PPI) determines how sharp and readable text and icons will be on your screen. A 27-inch 4K monitor has far higher pixel density than a 27-inch 1080p monitor, meaning it displays images with much greater clarity and detail.

What is Pixels Per Inch (PPI)?

Pixels Per Inch (PPI) is a measurement of the pixel density of a digital display, such as a smartphone screen, laptop panel, or desktop monitor. It describes how many physical pixels are packed into one diagonal inch of screen space. The higher the PPI, the smaller and more tightly clustered the pixels are, rendering text and images with extraordinary sharpness and clarity.

For most displays, a pixel density of 110 PPI or higher is considered excellent for desktop use, while laptops typically aim for 130+ PPI, and smartphones (held closer to the eyes) require 300+ PPI to achieve "Retina" status — where individual pixels are indistinguishable to the human eye at standard viewing distances.

How is PPI Calculated? (The Formula)

To calculate the PPI of any screen, you use the Pythagorean theorem to find the diagonal resolution in pixels, then divide it by the physical diagonal screen size in inches:

PPI = √(w² + h²) ÷ d

Where:

Why Pixel Density (PPI) Matters

Sharpness & Clarity

High-PPI displays deliver crisp text rendering and sharp image outlines, reducing eye strain during long hours of reading or programming.

UI Scaling (DPR)

On high-density displays (like Retina screens), operating systems apply UI scaling (increasing the Device Pixel Ratio) to make text readable while keeping icons smooth.

Effective Workspaces

Higher resolution screens at lower PPI (like huge ultrawide displays) give you more desktop workspace, whereas smaller screens with high PPI give you sharper quality but less physical space unless scaled down.

Common Displays and Their Pixel Densities

Here is a reference guide mapping standard resolutions, aspect ratios, and physical sizes to their exact PPI values:

Device / Screen Size Resolution Name Resolution (px) Aspect Ratio Pixel Density (PPI)
24" Desktop MonitorFull HD (1080p)1920 × 108016:991.8 PPI
27" Desktop MonitorFull HD (1080p)1920 × 108016:981.6 PPI
27" Developer MonitorQHD (1440p)2560 × 144016:9108.8 PPI
27" Premium Monitor4K Ultra HD3840 × 216016:9163.4 PPI
32" Desktop Monitor4K Ultra HD3840 × 216016:9137.7 PPI
34" Ultrawide MonitorUW-QHD3440 × 144021:9109.7 PPI
13.3" MacBook Air (M1)Retina Display2560 × 160016:10227.0 PPI
15.6" Standard LaptopFull HD (1080p)1920 × 108016:9141.2 PPI
iPhone 15 / 16 ProSuper Retina XDR2556 × 117919.5:9460.0 PPI

Frequently Asked Questions

What is a good PPI for a desktop monitor? ▼
For standard desk distances, 90 to 110 PPI is considered the sweet spot for native 100% scaling. If you go below 90 PPI (like a 27" 1080p monitor), text can look pixelated. If you go above 140 PPI (like a 27" 4K monitor), you will likely need to use 150% OS scaling to make text large enough to read, but it will be incredibly sharp.
What is the difference between PPI and DPI? ▼
PPI (Pixels Per Inch) refers to digital displays and the physical pixels on a screen. DPI (Dots Per Inch) refers to physical print output and the number of ink dots a printer places on a physical page. While the terms are sometimes used interchangeably in software settings, PPI is the correct hardware term for displays.
What is "Retina" screen density? ▼
"Retina" is a brand term introduced by Apple for displays where the pixel density is so high that individual pixels cannot be seen by the naked eye under normal viewing conditions. For phones (held 10" away), this is about 300+ PPI. For laptops (held 20" away), this is about 220+ PPI. For monitors (held 30" away), this is about 160+ PPI.
Does a higher PPI drain more battery? ▼
Yes. Screens with a higher PPI have more physical pixels that require more backlight power to shine through smaller pixel apertures, and the GPU must perform more work to render the additional pixels, resulting in higher power consumption.
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