Screen Resolution Tester
Detect your screen resolution, viewport size, pixel ratio, refresh rate, and color depth. Test for dead pixels and compare gaming monitor specs — all in your browser.
How your screen compares to standard resolutions.
Click a color to fill your entire screen. Press Esc or click anywhere to exit. Look for dots that don't match the displayed color.
Pixels per inch (PPI) at different screen sizes. Higher PPI = sharper image.
| Resolution | Name | 24" | 27" | 32" | Best For |
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See how your viewport compares to common devices. Green = your viewport is wider than that device.
Understanding Your Screen Specs
Resolution vs. Effective Resolution
Your screen resolution is the raw pixel count of your display. However, most modern operating systems use display scaling (100%, 125%, 150%, 200%) to make text and UI elements readable at high DPI. A 4K monitor (3840×2160) at 200% scaling behaves like a 1920×1080 display for layout purposes but renders text and images at 4× the detail. The "viewport" you see reported above reflects this scaled resolution.
Why Pixel Density Matters
Pixels per inch (PPI) determines how sharp your display looks. At normal desk viewing distances (2-3 feet), most people can't distinguish individual pixels above ~110 PPI. A 24" 1080p monitor has 92 PPI — you can see pixels if you look closely. A 27" 1440p monitor hits 109 PPI — the sweet spot for gaming. A 27" 4K monitor at 163 PPI is razor-sharp but requires a powerful GPU. For competitive gaming, 24-27" at 1080p or 1440p is ideal because you can maintain high frame rates without sacrificing too much sharpness.
Refresh Rate Detection
The refresh rate shown above is estimated using requestAnimationFrame timing. It may not be perfectly accurate — your actual monitor refresh rate is set in your OS display settings. Common gaming refresh rates are 60Hz (budget), 144Hz (competitive standard), 165Hz (common 1440p), 240Hz (high-end competitive), and 360Hz (pro esports). Make sure your Windows display settings are set to the maximum refresh rate your monitor supports — many monitors default to 60Hz even when they support 144Hz+.
Frequently Asked Questions
What's the difference between screen resolution and viewport size?
Screen resolution is the total number of physical pixels your monitor has (e.g., 1920×1080), while viewport size is the area your browser uses to display content. The viewport is always smaller than screen resolution because it excludes the browser's address bar, tabs, taskbar, and other UI chrome. On high-DPI displays (Retina, 4K), the viewport can also differ because the operating system scales content — a 3840×2160 screen at 200% scaling has an effective viewport of 1920×1080 CSS pixels. For gaming, screen resolution matters most. For web development, viewport size is what determines layout behavior.
What is device pixel ratio (DPR) and why does it matter for gaming?
Device pixel ratio is the number of physical pixels per CSS pixel. A DPR of 1 means one physical pixel equals one CSS pixel (standard 1080p/1440p monitors). A DPR of 2 means each CSS pixel is rendered with 4 physical pixels (2×2), which is common on Retina displays and 4K monitors at 200% scaling. For gaming, a higher DPR means your GPU has to render significantly more pixels — 4K at DPR 2 would be rendering at an effective 7680×4320, which is absurd. Most games bypass DPR entirely and render at native resolution. For streaming and content creation, understanding your DPR helps you capture screenshots and record video at the correct resolution.
How do I check if my monitor has dead pixels?
Use a dead pixel test by displaying solid colors across your entire screen — white, black, red, green, and blue. Dead pixels appear as tiny dots that don't change color. A stuck pixel shows as a bright dot on a black screen (it's permanently on), while a dead pixel appears as a dark dot on a white screen (it's permanently off). Stuck pixels can sometimes be fixed by rapidly cycling colors or applying gentle pressure with a soft cloth, but dead pixels are usually permanent. Most manufacturers allow 1-5 dead pixels before honoring a warranty replacement, though premium brands like Dell and ASUS have zero-dead-pixel policies on their gaming monitor lines.
What resolution should I use for competitive gaming — 1080p, 1440p, or 4K?
For competitive FPS games, 1080p at 240Hz+ is still the gold standard among pros. The reason is simple: lower resolution means higher frame rates and lower input lag. At 1080p, even mid-range GPUs can push 300+ FPS in games like Valorant and CS2, keeping frame times consistently below 4ms. 1440p at 165-240Hz is an excellent middle ground if you play a mix of competitive and AAA games — you get noticeably sharper text and details with only a 15-25% FPS drop versus 1080p. 4K gaming at 120Hz+ requires a top-tier GPU (RTX 4080/4090) and is best for single-player or story-driven games where visual quality matters more than raw FPS.
What aspect ratio is best for gaming — 16:9, 21:9, or 32:9?
16:9 is the standard and safest choice — all competitive games support it, and it offers the best performance since you're rendering fewer pixels than wider formats. 21:9 ultrawide (2560×1080 or 3440×1440) gives you more peripheral vision in supported games, which is a legitimate advantage in titles like Escape from Tarkov, Apex Legends, and flight sims. However, some competitive games like Valorant and Overwatch 2 don't support 21:9 and will add black bars. 32:9 super ultrawide (5120×1440) is immersive for sim racing and flight sims but is banned or unsupported in most competitive titles. Stick with 16:9 if you primarily play ranked FPS games.