Last updated: March 2026
How Screen Resolution Works
Every digital display is made of a grid of tiny light-emitting elements called pixels. Screen resolution tells you how many pixels wide and tall that grid is. A Full HD (1080p) screen arranges 1,920 pixels across and 1,080 pixels down, giving you roughly 2.07 million pixels total.
What makes modern displays confusing is display scaling. Operating systems routinely scale the UI to make text and icons readable at higher resolutions. A 4K laptop screen (3840x2160) might report its resolution as 1920x1080 in CSS pixels because the OS is using 200% scaling (DPR = 2). This tool shows both the CSS resolution and the calculated effective (physical) resolution.
Resolution alone does not determine display quality. Pixel density (PPI — pixels per inch) depends on both resolution and physical screen size. A 24-inch 4K monitor and a 6-inch 4K phone have the same resolution but wildly different pixel densities — roughly 183 PPI vs 734 PPI.
Common Screen Resolutions Compared
HD (720p) — 1280x720: Legacy resolution, still found on budget laptops and older TVs. 921,600 total pixels.
Full HD (1080p) — 1920x1080: The current standard for monitors, TVs, and streaming. 2,073,600 pixels. Accounts for about 23% of desktop market share.
QHD (1440p) — 2560x1440: Popular with gamers and professionals. 50% more pixels than 1080p. Sweet spot between sharpness and GPU performance.
4K UHD — 3840x2160: Four times the pixels of 1080p. Standard for premium monitors, TVs, and content creation. 8,294,400 total pixels.
5K — 5120x2880: Found on Apple Studio Display and iMac. 14,745,600 pixels — nearly twice 4K.
Frequently Asked Questions
What is my screen resolution?
Your screen resolution is shown at the top of this page. It reports the CSS pixel dimensions of your monitor (e.g., 1920x1080). Multiply by the Device Pixel Ratio to get the physical pixel count of your display.
What resolution is 4K?
4K resolution is 3840x2160 pixels, also called Ultra HD (UHD). It has four times the pixels of 1080p (1920x1080). True cinema 4K is slightly wider at 4096x2160, but consumer 4K is 3840x2160.
How do I change my screen resolution?
On Windows: Right-click desktop > Display settings > Display resolution. On macOS: System Settings > Displays > choose a resolution. On Linux: Settings > Displays. Lowering resolution makes everything larger; raising it gives you more screen space but smaller elements.
What is the most common screen resolution?
1920x1080 (Full HD) is the most common desktop resolution at about 23% market share globally. On mobile, the most common resolutions are 360x800 and 390x844, reflecting the dominance of mid-range Android phones and iPhones.
Does screen resolution affect performance?
Yes. Higher resolutions require more GPU power to render. A 4K display pushes 4x the pixels of 1080p, which can significantly impact gaming frame rates and battery life on laptops. For general web browsing and productivity, modern hardware handles any resolution smoothly.
What is the difference between resolution and screen size?
Screen size is the physical diagonal measurement of your display (e.g., 27 inches). Resolution is the number of pixels (e.g., 2560x1440). Two monitors can be the same size but have different resolutions — the higher-resolution one will have sharper, more detailed images.