Does browser zoom change viewport size?

Browser zoom can change the number of CSS pixels available to the page and the visual viewport scale. Results update live when the browser reports a change.

How do I test a responsive website at another viewport size?

Use the responsive breakpoint lab on this page for a quick visual check. For exact website rendering, use the responsive device mode in your browser developer tools.

Live display & browser measurements

Screen Resolution & Viewport Size Tester Online

Q: What is my screen resolution?

Your screen resolution is shown in the live results at the top of this page. Browsers normally report screen dimensions in CSS pixels.

Q: Is this online viewport size tester private?

Yes. Measurements are read by JavaScript in your browser. You do not need to upload a file or enter personal information.

Instantly check your screen dimensions, live browser viewport, device pixel ratio, orientation and responsive breakpoint—all in one clear, privacy-friendly dashboard.

Your browser viewport

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CSS pixels • updates while you resizeDetecting breakpoint

Your screen resolution

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Reported screen size in CSS pixels. The highlighted area below represents your current viewport.

Available screen—Excludes system interface areas

Device pixel ratio—Physical pixels per CSS pixel

Estimated physical—Screen size × pixel ratio

Orientation—Current screen direction

Browser window—Includes browser chrome

Layout viewport—Document rendering area

Color depth—Bits used to represent color

Visual scale—Visual viewport zoom scale

Private by design: display details are measured only inside your browser.

What each display measurement means

A screen, browser window and webpage viewport are related, but they are not the same size. This online screen size checker separates the measurements so you can use the right number.

Measurement	What it tells you
Screen resolution	The total width and height reported for your display in CSS pixels. Operating-system scaling may make this different from the panel’s advertised physical resolution.
Viewport size	The visible area available to the webpage, excluding most browser controls. This is the key measurement for responsive web design.
Available screen	The usable screen area after permanent system interface areas, such as a taskbar or dock, are excluded.
Device pixel ratio	The ratio between physical device pixels and CSS pixels. High-density displays commonly report a value greater than 1.
Browser window	The outside dimensions of the browser window, including tabs, toolbars, borders and other browser interface elements.

Measurement

What it tells you

Screen resolution

The total width and height reported for your display in CSS pixels. Operating-system scaling may make this different from the panel’s advertised physical resolution.

Viewport size

The visible area available to the webpage, excluding most browser controls. This is the key measurement for responsive web design.

Available screen

The usable screen area after permanent system interface areas, such as a taskbar or dock, are excluded.

Device pixel ratio

The ratio between physical device pixels and CSS pixels. High-density displays commonly report a value greater than 1.

Browser window

The outside dimensions of the browser window, including tabs, toolbars, borders and other browser interface elements.

Useful for design, development and support

CSS

Check responsive breakpoints

Resize the browser and see the live width and breakpoint label change, which helps when testing media queries and fluid layouts.

DPR

Prepare crisp graphics

Use device pixel ratio to understand why an image can look soft on a high-density screen and when higher-resolution assets may help.

Share clear bug details

Copy a compact display report for a designer, developer or support team instead of manually collecting every browser measurement.

Screen resolution and viewport tester FAQ

What is my screen resolution?

Your current screen resolution appears in the live dashboard near the top of this page. It is the width multiplied by the height reported by your browser in CSS pixels.

What is the difference between screen resolution and viewport size?

Screen resolution describes the display, while viewport size describes the browser area available to a web page. Tabs, toolbars, sidebars, developer tools and window size can all make the viewport smaller than the screen.

Why is the result different from my monitor’s advertised resolution?

Your operating system or browser may apply display scaling. Browsers expose CSS-pixel dimensions for web layout, so the reported size can differ from the hardware panel’s physical pixel count.

Does browser zoom change the viewport size?

It can. Zoom changes how CSS pixels map to the display, and supported browsers may also report a visual viewport scale. The tester updates whenever the browser sends a resize or visual viewport event.

How do I test a website at another viewport size?

Use the responsive breakpoint lab above for a quick visual model. To render a real site at exact dimensions, open the responsive device mode in your browser developer tools.

Is this online viewport size tester private?

Yes. The measurements are read locally in your browser. There is no file upload, account or personal information form.