Free Screen Resolution Detector Online

Screen Resolution Detector: See Exactly What Your Display Reports

A screen resolution detector reads the numbers your device's screen and browser already know about themselves — the physical screen resolution, the current browser viewport size, the available screen space, the device pixel ratio, color depth, and screen orientation — and displays them in one place instead of making you dig through operating system settings or browser developer tools to find them. Open the page and the six figures are already there, calculated the instant the tool loads, with a refresh button to recheck them after resizing the window or rotating a device.

There's nothing to type and nothing to configure: the tool simply asks your browser what it already knows about the screen it's currently running on and displays the answer as six labeled cards. It's less a converter or calculator than a straightforward readout — the entire job is measuring and displaying, with no input for you to provide beyond opening the page on the device you want to inspect.

How to Read Your Display's Numbers

1. Open the tool and look at the grid of cards that appears immediately — each one shows a label and a value, calculated the moment the page finishes loading.
2. Screen Resolution shows your monitor or display's full native resolution in pixels — width by height — regardless of how large your browser window currently is.
3. Viewport Size shows the size of the actual browser window content area right now, which is usually smaller than the full screen resolution unless the browser is maximized with no other windows or panels open.
4. Available Size shows the screen space left after your operating system's taskbar, dock, or menu bar is subtracted from the full screen resolution.
5. Device Pixel Ratio shows how many physical pixels the display packs into each CSS pixel — a number above 1 usually signals a high-density ("Retina" or similar) display.
6. Color Depth shows how many bits are used to represent color for each pixel, which determines how many distinct colors the display can show.
7. Orientation shows whether the current display is in a landscape or portrait layout, most relevant on tablets and phones that can be physically rotated.
8. If you resize the browser window, rotate a device, or move the window to a different monitor, click Refresh to recalculate all six values against the current state, since they aren't automatically re-measured while the page just sits open.

Why These Numbers Come Up So Often

Screen and viewport figures matter more often than most people expect, across a range of very different situations:

• Reporting a display bug accurately. Telling someone "it looks broken on my screen" is far less useful than telling them the exact resolution and pixel ratio where the problem shows up, especially when troubleshooting a layout issue that only appears at certain sizes.
• Choosing the right export size for an image or screenshot. Knowing your screen's actual resolution helps you decide whether a graphic, wallpaper, or screenshot needs to be captured or exported at a higher resolution than what you're currently seeing on screen.
• Understanding why a website or app looks different on two devices. A layout that looks perfect on one screen can look cramped or oversized on another purely because of differing viewport sizes or pixel ratios, and having the actual numbers in front of you makes that difference concrete instead of a vague impression.
• Checking whether a high-density display is actually being detected. The device pixel ratio figure confirms whether your system correctly recognizes a high-resolution screen, which affects how crisp text and images render.
• Verifying orientation-dependent behavior on a tablet or phone. Some layouts or apps are meant to behave differently in portrait versus landscape, and confirming which orientation the browser currently reports helps track down orientation-specific bugs.

Why a Server Can Never See These Numbers for You

Figure	Where it actually comes from
Screen Resolution	Read directly from your operating system's display settings via your browser
Viewport Size	Measured live from the browser window's current content area
Available Size	Calculated by your browser after subtracting OS-level UI like a taskbar or dock
Device Pixel Ratio	Reported by your device's display hardware and operating system together
Color Depth	Reported by your display and graphics configuration
Orientation	Reported by your device's screen orientation sensor or current window shape

Every one of these values is something only your own device can know, since a remote server has no line of sight into your monitor, your operating system's display settings, or how your browser window is currently sized — all a server ever sees, if anything, is whatever your browser optionally chooses to report in a request, and even that is far less detailed than what this tool reads directly. That's precisely why this kind of detector has to run client-side: the numbers describe your physical display and your browser window at this exact moment, and the only place that information genuinely exists is on the device you're using to read this sentence right now.

Making Sense of Numbers That Don't Match Expectations

A few of the figures regularly surprise people who haven't looked closely at how displays actually report themselves. Viewport size is almost never equal to screen resolution unless the browser window is maximized with nothing else visible, since any taskbar, browser toolbar, bookmarks bar, or open side panel eats into the usable content area — seeing a viewport noticeably smaller than the screen resolution is completely normal rather than a sign of a misconfigured display. Device pixel ratio confuses people most often on modern laptops and phones, where a ratio of 2 or 3 means the physical screen has two or three times as many actual pixels packed into the same space as a "standard" display, which is why a laptop with a technically enormous screen resolution can still describe its content in more modest, human-scale viewport numbers — the pixel ratio is quietly doing the scaling in between. Color depth rarely varies in practice on modern hardware, since nearly every current display and graphics setup reports the same standard value, so seeing an unusual number there is more often a sign of an older or unusual display configuration than routine variation. And orientation only changes meaningfully on devices that can physically rotate — a desktop monitor bolted in landscape orientation will simply always report landscape, since there's no sensor or rotating hinge involved for it to report anything else.

Screen Resolution vs. Viewport: The Distinction That Trips People Up Most

Of the six figures shown, the gap between screen resolution and viewport size causes more confusion than any of the others, largely because both are commonly shortened to just "resolution" in casual conversation despite measuring genuinely different things. Screen resolution is a fixed property of the physical display itself — set by the monitor's hardware and the operating system's display settings, and it doesn't change no matter how you resize or move the browser window around on top of it. Viewport size, in contrast, is entirely about the browser window's content area at this specific moment, and it changes the instant you resize the window, snap it to half the screen, or open a sidebar panel that eats into the available space. A designer asking "what resolution should I design for" is really asking about viewport size in the vast majority of cases, since that's what actually determines how much content is visible at once — screen resolution mostly matters for questions about display hardware itself, like whether a monitor supports a particular high-resolution mode. Mixing the two up is an easy mistake to make precisely because they're often close in value on a maximized browser window, which is exactly the situation where the difference stops mattering in practice and starts mattering again the moment either value changes independently of the other.

When You'd Actually Reach for a Tool Like This

Beyond idle curiosity about your own hardware, a few recurring tasks are the real reason this kind of detector gets used. Anyone filing a bug report about how a website or application renders benefits from pasting exact figures rather than a description, since "the button is cut off on my screen" means something different depending on whether the viewport is 1280 pixels wide or 390. Designers and developers checking how their own work looks across different real devices, rather than only in a browser's simulated device emulator, use a live reading like this to confirm what a visitor's browser is actually reporting rather than what a testing tool assumes. And anyone troubleshooting a display issue after connecting a new monitor, updating a graphics driver, or changing display scaling settings can use the numbers here as a quick, immediate confirmation that the new configuration is being recognized correctly, without opening a system settings panel to check.

Why is my viewport size smaller than my screen resolution?

Because viewport size measures only the browser window's content area, while screen resolution measures your entire physical display. Anything outside the browser's content area — a taskbar, dock, menu bar, browser toolbar, or another open window — reduces the viewport below the full screen resolution, which is expected rather than a problem.

What does a device pixel ratio above 1 actually mean?

It means your display packs more than one physical pixel into each CSS pixel used for layout — a ratio of 2, for instance, means four physical pixels (two by two) are used to render what's treated as a single pixel in web layout terms. This is typical of high-density displays and generally produces sharper text and images.

Will the numbers update automatically if I resize my browser window?

Not automatically — the values are calculated when the page loads and stay as they were until you click Refresh. After resizing the window, rotating a device, or moving to a different monitor, click Refresh to recalculate all six figures against the current state.

Is there an API for retrieving a visitor's screen resolution?

No, and this isn't a case where an API would even make sense — this tool reads values directly from your own browser and device, which a server has no access to at all. There's no server-side computation involved, so it isn't part of the site's metered API; it's purely an interactive client-side reading of your own screen.

Why does my color depth show the same number as everyone else I've asked?

Nearly all modern displays and graphics configurations report the same standard color depth value, so seeing identical numbers across different devices is normal rather than a sign that the tool isn't measuring accurately. Meaningful variation in this particular figure is uncommon on current hardware.

Why does orientation show "unknown" instead of landscape or portrait?

Some browsers or devices don't expose orientation information in a way the tool can read, particularly certain desktop setups without a rotation sensor involved at all. When that information genuinely isn't available from the browser, the tool reports it as unknown rather than guessing at a value it can't actually confirm.

Related Everyday Tools

For a broader read on how your browser identifies itself beyond just screen dimensions, the network category's user agent parser breaks down what your browser reports about itself and your operating system. If you're troubleshooting a connectivity issue alongside a display one, what is my IP shows the address your connection is currently using. And for jotting down the exact figures from a bug report while you investigate, the online notepad is a quick place to paste them.