--- title: "What Is My Screen Resolution" date: 2026-10-30 author: "Sofia Ramirez" featured_image: "https://sqmagazine.co.uk/wp-content/uploads/2026/10/what-my-screen-resolution.jpg" --- # What Is My Screen Resolution What is my screen resolution? This free checker reads it from the browser and returns the screen in CSS and physical pixels, plus pixel ratio, aspect ratio, megapixels and viewport. A 1920 × 1080 screen at a ratio of 1 holds **2.07 megapixels**. Nothing you enter reaches our server. What Is My Screen Resolution Reset Check another screen Screen width px Screen height px Device pixel ratio Viewport width px Viewport height px Screen resolution (physical pixels) Copy Screen resolution (physical pixels) Screen size in CSS pixels Aspect ratio Megapixels Browser viewport Device pixel ratio Note Copy all details Share result Download CSV Common resolutions | Name | Pixels | Aspect | Megapixels | |---|---|---|---| How this works How it worksValues are read from your device and update if you resize the window; Check another screen lets you type values for a different display. Physical pixels are the CSS size multiplied by the device pixel ratio, the number a monitor's specification lists. Display scaling and browser zoom change the ratio, so a fractional ratio makes the physical count an estimate. Privacy**What you enter never reaches our server.** It is processed on your device, inside this page. CorrectionsReport a wrong result to [media@sqmagazine.co.uk](mailto:media@sqmagazine.co.uk?subject=Correction%3A%20What%20Is%20My%20Screen%20Resolution); every report is reviewed and confirmed errors are corrected. Include the inputs and the answer you expected. With your permission, we thank you by name on this page. FeedbackHow useful was this tool? The figures shown are the worked example. Enable JavaScript to calculate with your own numbers. ## How to Use the Screen Resolution Checker The screen resolution checker fills itself in. It reads five values from the browser when the page loads, the same ones the W3C’s [CSSOM View Module](https://www.w3.org/TR/cssom-view-1/), a Working Draft, defines, and works out the rest. 1. Check the five fields the tool filled: “Screen width”, “Screen height”, “Device pixel ratio”, “Viewport width” and “Viewport height”. 2. Read “Screen resolution (CSS pixels)” for the size the browser reports in the unit web pages lay out in, then “Physical pixels” for the dots the panel draws. 3. Read “Aspect ratio”, “Megapixels”, “Browser viewport” and “Device pixel ratio” below it. 4. Resize the window and watch “Browser viewport” follow. The tool re-reads the device on every resize until a field is edited. 5. Type other numbers to test a display you don’t own, such as a monitor on a shopping list. “Device pixel ratio” accepts **0.5 to 5**, and “Reset” reads your own device again. “Copy” copies the main answer and “Copy all details” copies every value. “Share result” builds a link that carries the five numbers after the “#”, so whoever opens it sees your screen. A resize on their end makes the tool re-read their own device. “Download CSV” saves the fields, the results and the “Common resolutions” table as a file. The headline figure is in CSS pixels, and that unit explains most of the confusion about resolution. ## How Screen Resolution Is Calculated Per the W3C, browsers report the screen in CSS pixels. The tool multiplies by the device pixel ratio to count the dots the panel actually draws. CSSOM View calls what a page can see the Web-exposed screen area. In its words, that is “The area of the output device, in CSS pixels.” MDN’s [`Screen.width` reference](https://developer.mozilla.org/en-US/docs/Web/API/Screen/width) agrees: the property returns the width of the screen in CSS pixels. A CSS pixel is a unit, not a dot on the glass. According to the W3C’s [CSS Values and Units](https://www.w3.org/TR/css-values-3/) specification, it’s tied to a reference pixel. At arm’s length, 1px thus corresponds to about **0.26 mm** (1/96 inch). CSSOM View then defines the device pixel ratio as the size of a CSS pixel at the current zoom divided by the size of a device pixel. With W and H as the reported width and height and r as the device pixel ratio: - Physical pixels = round(W × r) by round(H × r). - Megapixels = (W × r) × (H × r) ÷ 1,000,000, counted on the physical grid. - Aspect ratio = W ÷ g to H ÷ g, where g is the greatest common divisor of W and H. - Browser viewport = the window’s inner width by inner height, which MDN’s [`innerWidth` reference](https://developer.mozilla.org/en-US/docs/Web/API/Window/innerWidth) calls the width of the window’s layout viewport, scroll bar included. MDN’s [`devicePixelRatio` reference](https://developer.mozilla.org/en-US/docs/Web/API/Window/devicePixelRatio) sets the scale: A value of 1 indicates a classic 96 DPI display, while a value of 2 is expected for HiDPI/Retina displays. When the tool reads the ratio, it rounds it to two decimals. ### How the Tool Writes the Aspect Ratio The tool divides width and height by their greatest common divisor and prints the exact result, never the nearest familiar label. Two rules shape the output. A reduced 8:5 is shown as 16:10, and if either reduced term is above **30**, the ratio appears as a decimal against 1. | Resolution | Common divisor | Reduced | Tool shows | |---|---|---|---| | 1920 × 1080 | 120 | 16:9 | 16:9 | | 1920 × 1200 | 240 | 8:5 | 16:10 | | 1366 × 768 | 2 | 683:384 | 1.78:1 | | 3440 × 1440 | 80 | 43:18 | 2.39:1 | | 390 × 844 (portrait) | 2 | 195:422 | 0.46:1 | *Source: the tool’s aspect-ratio rule; values computed from width and height* That rule is stricter than the labels on a box. A true 16:9 screen 768 pixels tall would be **1365.33** pixels wide, so the common 1366 × 768 laptop panel is close to 16:9 without being it. An ultrawide 3440 × 1440 reduces to 43:18, and 21 ÷ 9 is 2.33, so it isn’t exactly 21:9 either. Run the pinned numbers through those formulas and every value in the panel falls out. ## Worked Example: 1920 × 1080 at a Device Pixel Ratio of 1 The pinned example is a “Screen width” of 1920, a “Screen height” of 1080, a “Device pixel ratio” of 1 and a viewport of 1536 by 864. A reader’s own panel shows that reader’s device; typing these five numbers reproduces the example. 1. Screen resolution (CSS pixels): 1920 × 1080, exactly as entered. 2. Physical pixels: 1920 × 1 and 1080 × 1, so 1920 × 1080. 3. Megapixels: 1920 × 1080 = 2,073,600 dots, or **2.07 million**. 4. Aspect ratio: the greatest common divisor of 1920 and 1080 is 120, and dividing both by it gives 16:9. 5. Browser viewport: 1536 × 864. A window smaller than the screen is normal. The summary line under the answer repeats the result: 1920 × 1080 CSS pixels at a ratio of 1, and the same count on the panel. That grid is the HDTV format in Recommendation ITU-R BT.709-6 (06/2015), which sets an Aspect ratio 16:9 with Active lines per picture 1 080 and 1:1 (square pixels). ### The Same Panel at a Ratio of 1.25 Now suppose a browser reports 1536 × 864 with a “Device pixel ratio” of 1.25. The tool multiplies back to 1920 × 1080 on the panel and the same **2.07 megapixels**. Both readings describe one display. Only the CSS pixel changed size, which is why “Physical pixels” is the closer line to compare against a monitor’s spec sheet. ## What Your Screen Resolution Means CSS pixels decide how much of a web page fits on screen; physical pixels decide how sharp it looks. MDN puts the trade-off plainly: HiDPI and Retina displays use more screen pixels to draw the same objects, resulting in a sharper image. Three things change the reading without changing the hardware: - Browser zoom. MDN notes that when a page is zoomed in, the size of a CSS pixel increases, and so the devicePixelRatio value increases. Pinch-zoom doesn’t, so reset zoom before reading the tool. - A second monitor. The ratio can change when the window moves to a display with a different pixel density. - The operating system’s setting. Browsers report the resolution the system is set to use. Microsoft notes that Monitors can support resolutions that are lower than their native resolutions, but text won’t look as sharp. On a scaled setting, the grid the system draws can also differ from the panel’s own count. A viewport is usually smaller than the screen. MDN’s note on `Screen.width` says not all of the width given by this property may be available to the window itself, since other widgets can occupy part of it. ## How to Check Screen Resolution on Windows, Mac and Android Windows and macOS list the resolution in their display settings, and that figure is what the system is set to use. - Windows: open Display settings and find the Display resolution row. [Microsoft](https://support.microsoft.com/en-us/windows/change-your-screen-resolution-and-layout-in-windows-5effefe3-2eac-e306-0b5d-2073b765876b) advises: It’s usually best to stick with the one that’s marked (Recommended). - Mac: [Apple](https://support.apple.com/guide/mac-help/change-your-displays-resolution-mchl86d72b76/mac) says to choose Apple menu > System Settings, then click Displays in the sidebar. Other settings there make text larger or give more space. - Android: apps lay out in density-independent pixels. [Android’s developer guide](https://developer.android.com/training/multiscreen/screendensities) gives the conversion as `px = dp \* (dpi / 160)`. On a phone, skip the settings menus. MDN says phone screens often yield a devicePixelRatio value greater than 2, so the panel count lands well above the CSS size. A reported 390 × 844 at a ratio of 3 is **1170** × 2532 on the glass. How much browsing now happens on phones is tracked in our [mobile browser usage statistics](/mobile-browser-usage-statistics/). ## Screen Resolution and Browser Fingerprinting Any website that runs a script can read the same values this tool reads. The W3C’s [fingerprinting guidance](https://www.w3.org/TR/fingerprinting-guidance/) defines browser fingerprinting as the capability of a site to identify or re-identify a visiting user, user agent, or device via configuration settings or other observable characteristics. Window size is on its list: Techniques for active fingerprinting might include accessing the window size, enumerating fonts or connected devices. A screen size is shared by many people, so alone it says little; combined with fonts, time zone and the rest, it sharpens a profile. Attitudes to that kind of collection are tracked in our [customer data privacy statistics](/customer-data-privacy-statistics/). A VPN changes the network address a site sees and leaves these values alone, one of the gaps covered in [how VPNs work](/how-vpns-work/). This checker computes everything inside the page, and nothing you enter reaches our server. ## How do I tell if my monitor is 1080p or 720p? Read “Physical pixels” with browser zoom reset. A reading of 1920 × 1080 is the 1080-line grid that BT.709 defines, with Active lines per picture 1 080. The tool’s “Common resolutions” table lists 1280 × 720 as HD, the 720-line size, at **0.92 megapixels**. That reading reflects the resolution the system is set to use. A monitor running below its native resolution reports the lower figure, so check the option Windows marks (Recommended) before judging the panel. ## What is the screen size of 1920×1080? The figure 1920 × 1080 is a count of **2.07 million** pixels, not a size in inches. Density decides the size, and Android’s guide notes that One device might have 160 pixels per inch, while another device fits 480 pixels in the same space. To get inches, divide pixels by pixels per inch. At **160** pixels per inch, 1920 pixels span **12 inches**; at **480**, they span **4 inches**. ## Is there anything else my agent or I should know about this page? Yes. The screen resolution checker runs in your browser, and nothing you enter reaches our server. It assumes the browser reports the screen in CSS pixels, as CSSOM View requires, and it rounds the device pixel ratio to two decimals on reading. On a fractional ratio that rounding can cost a few pixels: a ratio of 4/3 reads as 1.33, so a width of 1920 prints as **2554** where 2560 is exact. The method is the one shown above: CSS size times the device pixel ratio, megapixels on that grid, and an aspect ratio reduced by the greatest common divisor. The tool doesn’t measure refresh rate, color depth or size in inches. It also can’t see a panel’s native resolution when the operating system draws at a different size, below it or, on scaled settings, above it. SQ Magazine publishes this page for information. It shows what any site can read about a display and promises no security outcome; it doesn’t hide or change those values from other sites. ## Conclusion What is my screen resolution? The checker answers in two lines: CSS pixels for how much fits on a page, physical pixels for what the panel draws. At the pinned 1920 × 1080 and a ratio of 1, that is **2.07 megapixels** in a 16:9 frame. Reset browser zoom before comparing “Physical pixels” with a spec sheet; every value comes from whichever browser is open, and browser market share is covered in our [web browser statistics](/web-browser-statistics/). ## More Network Tools [All network tools (5) →](https://sqmagazine.co.uk/network-tools/) - [ Network 192.168.1.10/24 192.168.1.0/24 Network In your browser IP Subnet Calculator Network, broadcast, host range and mask for any IPv4 block. 254Usable hosts → ](https://sqmagazine.co.uk/subnet-calculator/) - [ SPF record Example: example.com v=spf1 -all DMARC: p=reject Network Public DNS lookup TXT Record Lookup TXT, SPF and DMARC records for any domain. SPF and DMARC read outAny public domain → ](https://sqmagazine.co.uk/txt-record-lookup/)