Enter the pixel width (in pixels) and the physical width (e.g., in micrometers) into the calculator to determine the pixel density (e.g., px/µm or PPI).
Resolution Formula
The following formula is used to calculate pixel density (sometimes informally called “resolution” in px per unit length).
R = Wp/ Wum
- Where R is the pixel density (pixels/micrometer, i.e., px/µm)
- Wp is the width in pixels (pixel count)
- Wum is the physical width in micrometers
To calculate the pixel density (px/µm), divide the width or length in pixels by the physical width or length in micrometers.
Resolution Definition
In this calculator, “resolution” refers to pixel density (pixels per unit length), such as px/µm or pixels per inch (PPI). Note that in many display and image contexts, “resolution” can also mean the pixel dimensions (for example, 1920×1080), which is a different concept from pixel density.
Resolution Example
How to calculate a resolution.
- First, determine the number of pixels.
Measure the total number of pixels across the image/sensor/display.
- Next, determine the physical width.
Measure the total physical width in micrometers (or convert another length unit to micrometers).
- Finally, calculate the pixel density.
Use the formula above to calculate pixel density (px/µm).
FAQ
How does pixel density affect image quality?
Pixel density, measured in pixels per inch (PPI) or other pixels-per-length units (such as px/mm or px/µm), affects how much detail can be shown at a given physical size. Higher pixel density means more pixels are packed into the same physical space, which can make images look sharper when viewed or printed at that size.
Why is resolution important in digital displays?
Both pixel dimensions (often called “resolution,” e.g., 1920×1080) and pixel density (PPI) matter. Higher pixel dimensions can show more detail overall, and higher pixel density can make content look sharper at the same physical screen size and viewing distance.
Can resolution affect the file size of images and videos?
File size depends primarily on the total number of pixels (pixel dimensions) and compression/encoding settings. Increasing pixel dimensions usually increases file size, while changing only the PPI/px-per-length metadata (without resampling to change pixel dimensions) typically does not change file size.
