How to use the Screen Resolution Checker
- Open the page: your screen resolution in physical pixels is shown at the top straight away.
- Compare the screen size, available area and browser viewport in the boxes below.
- Resize your browser window or rotate your phone to watch the viewport and orientation update live.
- Click Copy all details to paste the results into a support ticket or bug report.
Features
- Physical resolution calculated from CSS size and pixel ratio
- Screen, available area and live browser viewport sizes
- Device pixel ratio, aspect ratio and orientation
- Color depth, color gamut and HDR support
- Estimated refresh rate measured from animation frames
- Common resolutions table with your match highlighted
Physical pixels versus CSS pixels
Modern screens pack so many pixels that if websites used them one-for-one, text would be unreadably small. Operating systems and browsers therefore work in CSS pixels (also called logical or device-independent pixels) and scale them up. The device pixel ratio (DPR) says how many physical pixels make up one CSS pixel in each direction.
Physical resolution = CSS size × device pixel ratio. A laptop that reports 1440 × 900 CSS pixels at a DPR of 2 has a 2880 × 1800 panel. A phone that reports 390 × 844 at a DPR of 3 has 1170 × 2532 physical pixels. Windows display scaling works the same way: a 1920 × 1080 monitor at 125% scaling reports 1536 × 864 CSS pixels and a DPR of 1.25.
Browser zoom also changes the DPR, so if the numbers look odd, press Ctrl+0 (Cmd+0 on a Mac) to reset zoom and check again. Rounding at fractional scaling levels can make the calculated physical size differ from the panel’s specification by a pixel or two.
Screen, available area and viewport
- Screen size is the whole display in CSS pixels.
- Available subtracts permanent system areas such as the Windows taskbar or macOS menu bar and Dock.
- Viewport is the part of the browser window where pages are drawn, excluding tabs, address bar and scrollbar edges in some browsers. This is the size that responsive designs and CSS media queries respond to, so it matters most to web designers.
Aspect ratios explained
| Aspect ratio | Example resolutions | Where you see it |
|---|---|---|
| 16:9 | 1920 × 1080, 2560 × 1440, 3840 × 2160 | Most monitors, TVs and video |
| 16:10 | 1920 × 1200, 2560 × 1600 | Productivity laptops and monitors |
| 3:2 | 2256 × 1504, 2880 × 1920 | Some 2-in-1 laptops and tablets |
| 21:9 | 2560 × 1080, 3440 × 1440 | Ultrawide monitors (actual ratios are close to 21:9) |
| 20:9 and taller | 1080 × 2400 | Modern phones held upright |
Color depth, gamut and refresh rate
Color depth is the number of bits used per pixel; browsers usually report 24-bit (8 bits per red, green and blue channel, about 16.7 million colors) or 30-bit on capable systems. Color gamut tells you whether the display covers standard sRGB or a wider range such as Display P3, which shows more saturated reds and greens. The refresh rate is estimated by counting animation frames for one second; a 60 Hz panel redraws 60 times per second, while gaming displays run at 120, 144 Hz or more. Battery-saving modes and background tabs can lower the measured figure.
Why it is useful
Knowing your exact resolution helps when choosing wallpapers, setting up screen recordings, buying a monitor, filling in a bug report or testing responsive websites. To create images at the right size, use the Image Resizer, and to check your camera or microphone before a call, try the Webcam Test and Mic Test.
Frequently asked questions
Why is my resolution lower than my monitor’s specification?
The screen size is reported in CSS pixels, which are scaled by your operating system. Multiply by the device pixel ratio to get physical pixels; the big number at the top already does this.
What is device pixel ratio?
It is how many physical pixels make up one CSS pixel. A ratio of 2 means each CSS pixel is drawn with a 2 × 2 block of real pixels, which makes text and images sharper.
Why does the viewport change when I resize the window?
The viewport is the visible page area inside the browser, so it follows the window size. The screen resolution itself stays the same.
Is the refresh rate exact?
It is an estimate based on how often the browser draws frames. Power saving, background tabs or a busy computer can make it read lower than the display’s true rate.
Does browser zoom affect the results?
Yes. Zooming changes the device pixel ratio and the CSS sizes. Reset zoom to 100% for accurate screen numbers.