DPI / PPI 计算器
指导
DPI / PPI 计算器
Calculate the pixel density (PPI/DPI) of any screen from its resolution and physical diagonal size. Enter width and height in pixels and the diagonal screen size in inches to instantly see pixels per inch, dot pitch, total pixel count, and a full display properties table.
如何使用
Enter your display’s width and height resolution in pixels and its physical diagonal size in inches. All metrics calculate instantly: PPI, dot pitch (mm), aspect ratio, total pixel count, and megapixels.
特征
- PPI calculation – pixels per inch from resolution and physical size
- Dot pitch – physical size of each pixel in millimetres
- Full properties table – aspect ratio, megapixels, total pixel count
- Common display sizes – context for typical PPI ranges by device type
- 实时结果 – updates as you type any value
- 仅客户端 – 未将数据发送到服务器
常问问题
-
What is the difference between DPI and PPI?
PPI (Pixels Per Inch) refers to the pixel density of a digital display — how many pixels fit in one inch of screen space. DPI (Dots Per Inch) originally referred to printer resolution — how many ink dots a printer places per inch. In digital contexts the terms are often used interchangeably, but technically PPI is the correct term for screens while DPI applies to printers and physical output. A 4K monitor at 27 inches has roughly 163 PPI.
-
What PPI is considered Retina quality?
Apple coined the term Retina Display for screens where individual pixels are indistinguishable at normal viewing distance. The threshold depends on viewing distance: approximately 300 PPI for phones (held ~30cm away), 220 PPI for tablets (~40cm), and 110 PPI for desktop monitors (~70cm). Most modern smartphones exceed 400 PPI, 4K monitors at 27 inches are around 163 PPI, and 4K at 24 inches reaches 184 PPI.
-
How does dot pitch relate to PPI?
Dot pitch is the physical size of one pixel, measured in millimetres: Dot Pitch (mm) = 25.4 / PPI. A display with 100 PPI has a dot pitch of 0.254mm. Lower dot pitch means higher pixel density and sharper images. Dot pitch is particularly relevant for monitors viewed at close range and for print design where precise physical dimensions matter.
-
Why do screens with the same resolution look different at different sizes?
Resolution only describes the total pixel count. A 1920×1080 screen at 24 inches has 92 PPI while the same resolution at 32 inches has 69 PPI — the larger screen has the same number of pixels spread over more physical area, making each pixel bigger and the image less sharp. This is why 4K resolution provides a significant sharpness improvement at 27 inches but a smaller relative improvement at 40+ inches.
