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What is my screen resolution?

Detect your monitor screen resolution in pixels. Free online tool — no sign-up. Clear formulas and worked examples. Runs locally in your browser.

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How to use

1

Open on the device to measure

Load the tool in the browser window or display you care about.

2

Read the live metrics

Check width × height in CSS pixels (screen and/or viewport, depending on the page).

3

Resize and compare

Resize the window or switch displays, then refresh the readout for responsive checks.

Screen resolution specification

Version 1.0.0 · Engine tested

Calculation status
  • Engine tested 1 published cases
  • Named expert review Not performed
  • Calculation version 1.0.0

Review policy

Definition
Screen resolution tools report the display’s pixel dimensions (and related viewport metrics) available to the browser.
What it calculates
Reads screen.width/height and related display metrics exposed by the browser.
Inputs
  • None — uses the current display environment
Outputs
  • Screen width × height in CSS pixels (and related values when shown)
Formula
resolution = screen.width × screen.height

This tool detects your screen resolution — the number of pixels your display shows horizontally and vertically. Screen resolution is reported as width × height (e.g., 1920×1080).

What the tool shows

Property Description
Screen width Total horizontal pixels
Screen height Total vertical pixels
Color depth Bits per pixel (typically 24 or 32)
Device pixel ratio Physical pixels per CSS pixel

Screen resolution vs. viewport

Term Meaning
Screen resolution Full monitor pixel count
Viewport Visible browser area (may be smaller)
Window size Current browser window dimensions

Check viewport with What is my browser window size?.

Common resolutions

Resolution Typical device
1920×1080 Desktop monitor (Full HD)
1366×768 Laptop
2560×1440 QHD monitor
3840×2160 4K monitor
390×844 Modern smartphone

Compare with window size for viewport vs display dimensions.

Why resolution matters for web design

  • Design responsive layouts that adapt to any screen size
  • Set appropriate breakpoints in CSS media queries
  • Test with Website Screen Resolution Tester
  • Optimize images for common display sizes
Assumptions
  • Values come from the browser Screen API.
  • Local read only.
Units
  • px
Boundary conditions
  • Multi-monitor setups report the screen associated with the window.
Example
1920×1080 display → 1920 × 1080
Validation cases
  • Typical laptop → Matches OS display resolution in CSS px
Sources
  • CSSOM View — Screen interface
Calculation version
1.0.0
→ Window size › → Screen resolution tester › → Pixel ruler ›

Frequently asked questions

Key distinctions behind the tool.

Why does this differ from my OS display settings?

Browsers report CSS pixels; OS scaling and multiple displays can change the relationship to physical pixels.

Is this the same as window size?

No. Screen resolution is the display; window size is the browser viewport/window.