What Is My Screen Resolution? – Check Screen Size & Pixel Ratio
See your screen resolution, the real number of physical pixels, the device pixel ratio, the size of your browser window and more — measured live as you resize.
Your screen resolution is shown at the top in CSS pixels, with the physical resolution below it (CSS pixels × device pixel ratio). For example, a laptop showing 1440 × 900 at a ratio of 2 has a 2880 × 1800 panel. The browser window size updates when you resize it.
How to use Screen Resolution
- Open the page — the resolution is detected automatically.
- Read the screen size and the physical pixels.
- Check the device pixel ratio to see if you have a high-DPI screen.
- Resize the browser to see the window size change.
- Move the window to another monitor to compare screens.
CSS pixels vs physical pixels
Modern screens pack more pixels into the same space, so operating systems scale everything up to keep text readable. Browsers report sizes in "CSS pixels" — the scaled size — and the device pixel ratio (DPR) tells you how many physical pixels each CSS pixel uses.
| Device example | CSS size | DPR | Physical |
|---|---|---|---|
| Full HD monitor | 1920 × 1080 | 1 | 1920 × 1080 |
| Laptop at 150 % scaling | 1280 × 720 | 1.5 | 1920 × 1080 |
| MacBook Air 13" | 1440 × 900 | 2 | 2880 × 1800 |
| Modern phone | 390 × 844 | 3 | 1170 × 2532 |
The physical value can be slightly off when scaling is not a whole number, because browsers round the CSS size.
Screen vs window vs available
- Screen resolution — the whole display.
- Available screen — the screen minus the taskbar or dock.
- Browser window (viewport) — the area a web page can actually use. This is the number web designers care about for responsive layouts.
Zooming the page changes the window size and pixel ratio too, so reset zoom (Ctrl/Cmd + 0) for accurate numbers.
Refresh rate
The tool estimates the refresh rate by counting how often the browser draws a frame. Typical results are 60, 90, 120 or 144 Hz. Battery saving, a background tab or a busy computer can make the estimate lower. Check your display settings for the exact value.
Colour depth
Most screens report 24 bits (8 bits per colour channel, 16.7 million colours). HDR-capable displays may report 30 bits.
Why it is useful
- Pick the right size for a wallpaper or screenshot.
- Check that a new monitor runs at its native resolution.
- Help support teams and web developers reproduce a layout problem.
- Choose image sizes: a 2× screen needs images twice the CSS size to look sharp, which you can prepare with the Image Resizer.
Nothing is sent to a server — all values are read by your browser. Your browser details are on the What Is My User Agent page.
You may also find these free tools useful: Keyboard Tester, Gamepad Tester and What Is My User Agent.
Frequently asked questions
What is my screen resolution?
It is shown at the top of this page. The first value is in CSS pixels; the physical resolution is that value multiplied by the device pixel ratio.
What is device pixel ratio?
It is how many physical screen pixels make up one CSS pixel. 1 on standard monitors, 2 or 3 on Retina and phone screens.
Why is my resolution lower than my monitor spec?
Display scaling such as 125 % or 150 % makes the browser report a smaller CSS size. Multiply by the pixel ratio to get the physical size.
What is the browser window size?
It is the area inside the browser that a web page can use, also called the viewport.
How accurate is the refresh rate?
It is an estimate based on drawn frames. Check your display settings for the exact value.
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