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Website Screen Resolution Tester

Test how your website looks at different screen resolutions. Free online tool — no sign-up. Built for quick, accurate checks. 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 tester 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
A screen resolution tester helps verify how layouts respond at common display sizes using live browser metrics.
What it calculates
Compares or displays resolution/viewport metrics for responsive checks.
Inputs
  • Current display / viewport environment
Outputs
  • Resolution and related size readouts
Formula
Read screen and viewport dimensions from the browser APIs

The Website Screen Resolution Tester simulates how a website appears at different display sizes. Enter a URL and select a resolution to preview the page in a device-sized frame.

How to use

  1. Enter the website URL to test
  2. Select a screen resolution preset or enter custom dimensions
  3. View the page rendered at that size
  4. Check layout, readability, and responsive behavior

Common test resolutions

Resolution Device type
375×667 iPhone SE / small mobile
390×844 iPhone 14/15
768×1024 iPad portrait
1366×768 Laptop
1920×1080 Desktop Full HD
2560×1440 QHD monitor

Compare with screen resolution and window size.

What to check

  • Navigation — menu accessible at all sizes?
  • Text readability — font sizes appropriate on mobile?
  • Images — scale correctly without overflow?
  • Buttons — large enough to tap on touch screens?
  • Horizontal scroll — any unwanted overflow?

Responsive design tips

  • Use CSS media queries at common breakpoints
  • Test both portrait and landscape orientations
  • Check window size vs. full screen resolution
  • Use Online Ruler to verify element dimensions
Assumptions
  • Local metrics only.
  • Useful alongside DevTools device emulation.
Units
  • px
Boundary conditions
  • Emulated devices may differ from physical hardware.
Example
Resize or move the window and re-check width × height
Validation cases
  • Fullscreen window → Viewport approaches screen size
Sources
  • CSSOM View — Screen / VisualViewport
Calculation version
1.0.0
→ Screen resolution › → Window size ›

Frequently asked questions

Key distinctions behind the tool.

Should I test only screen size?

Also test viewport and breakpoints—users rarely browse at exact screen resolution.