Screen Resolution Checker

‘What is my screen resolution?’ sounds simple until you learn there are three different numbers that all claim the title: your display’s true pixel resolution, the CSS resolution your browser uses after scaling, and the current viewport size of the window itself. Our free screen resolution checker shows all of them at once, updates live as you resize the window or rotate your phone, and reports your device pixel ratio and orientation too. It is the quickest way to answer the question for tech support, check a responsive design breakpoint, or confirm a new monitor is running at its native resolution.

Quick Answer: Your screen resolution, available area, browser viewport, pixel ratio and orientation are shown instantly and update live as you resize the window or rotate your device.

Free Online Tool

Live sizes for your display and browser window. Resize or rotate to see them change.

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Your screen resolution (physical pixels)

–CSS resolution

–Viewport size

–Pixel ratio

–Orientation

–Viewport class

Table of Contents

How to Use the Screen Resolution Checker

Look at the big number first: that is your screen’s resolution in physical pixels.
Compare it with the CSS resolution underneath; a difference means your display is scaled (common on laptops and retina screens).
Resize your browser window and watch the viewport figures change in real time, which is what responsive designs actually respond to.
Rotate your phone or tablet to see the orientation flip between portrait and landscape.
Note the device pixel ratio: 2 or higher means a high-density display that needs double-size images to look sharp.

Key Features

All the size numbers in one place: physical resolution, CSS resolution, available area and live viewport.
Real-time updates on window resize and device rotation with no refresh needed.
Device pixel ratio and orientation reported alongside the sizes.
Breakpoint indicator showing which common responsive range your current viewport falls into.
Runs entirely in your browser; no information about your device leaves it.

Best Practices and Tips

When reporting a website bug, quote the viewport size, not the screen size: layout responds to the window, not the monitor.
If text looks blurry on a new external monitor, check that the physical resolution shown matches the monitor’s native specification.
Designers: drag your desktop window slowly narrower and watch the breakpoint label to find exactly where a layout should switch.
A pixel ratio of 1.25 or 1.5 usually means Windows display scaling is on; that is normal for high-resolution laptop screens.

Common Mistakes to Avoid

Assuming your 4K monitor means websites see 3840 CSS pixels; with scaling they typically see 1920 or fewer, which is correct behaviour.
Testing a ‘mobile view’ by only narrowing a desktop window; real devices also differ in pixel ratio, touch and viewport behaviour.
Confusing the available screen area (which excludes taskbars) with the full resolution when calculating window layouts.

Frequently Asked Questions

What is the difference between screen resolution and viewport size?

Screen resolution is your display’s total pixels. The viewport is the part of the browser window where the page itself renders, excluding tabs, toolbars and scrollbars. Responsive design breakpoints react to the viewport, which is why both numbers matter.

What does device pixel ratio mean?

It is the ratio between physical pixels and CSS pixels. A ratio of 2 means each CSS pixel is drawn with 4 physical pixels (2×2), producing sharper text and images. Phones and retina laptops commonly report 2 or 3.

Why is my CSS resolution lower than my screen resolution?

Because of display scaling. Operating systems enlarge the interface on high-resolution screens so text stays readable, and browsers report the scaled (CSS) size to websites. Both numbers shown here are correct; they measure different things.

How do I check if my monitor is at its native resolution?

Compare the physical resolution shown here with the manufacturer’s specification for your monitor. If they differ, adjust the display settings in your operating system to the recommended (native) value.

Does this tool work on phones and tablets?

Yes. It reports the phone’s screen and viewport sizes and updates when you rotate the device, making it handy for checking mobile breakpoints on real hardware.