Screen resolution is accessed through the JavaScript screen object, specifically the screen.width and screen.height properties. These values represent the total pixel dimensions of your physical display:
The screen object was introduced in early JavaScript (Netscape Navigator 2.0, 1996) to help web developers create layouts that adapt to different display sizes. At the time, monitors varied widely in resolution, and developers needed to know screen dimensions to optimize content presentation.
Screen resolutions have evolved dramatically over the decades:
Standard resolutions: 640x480, 800x600, 1024x768
Widescreen becomes popular: 1280x1024, 1440x900, 1920x1080
Retina displays, 4K monitors: 2560x1440, 3840x2160, 5120x2880
Ultra-wide displays: 3440x1440, 5120x1440; Multi-monitor setups increasingly common
| Resolution | Common Name | Aspect Ratio | Usage |
|---|---|---|---|
1920×1080 |
Full HD / 1080p | 16:9 | Most common desktop/laptop resolution |
1366×768 |
HD / WXGA | ~16:9 | Budget laptops, older displays |
2560×1440 |
QHD / 1440p | 16:9 | High-end monitors, gaming displays |
3840×2160 |
4K UHD | 16:9 | Premium monitors, content creation |
2880×1800 |
Retina Display | 16:10 | MacBook Pro (pre-2021) |
3456×2234 |
Retina Display | ~16:10 | MacBook Pro 14" (2021+) |
3024×1964 |
Retina Display | ~16:10 | MacBook Air 13" (M2, 2022+) |
| Resolution | Device Examples | Notes |
|---|---|---|
390×844 |
iPhone 13/14/15 | CSS pixels (actual physical resolution higher) |
393×851 |
iPhone 15 Pro | Slightly larger display |
360×800 |
Samsung Galaxy S21 | Common Android resolution |
412×915 |
Google Pixel 7 | Standard Android flagship size |
820×1180 |
iPad Air (2022) | Tablet resolution in portrait |
3440×1440 - Ultra-wide 21:9 monitors5120×1440 - Super ultra-wide 32:9 monitors1600×1200 - Legacy 4:3 displays1280×1024 - Legacy 5:4 displays| Platform | Behavior | Notes |
|---|---|---|
| Windows | Reports logical resolution | Affected by Windows display scaling settings (125%, 150%, etc.) |
| macOS | Reports Retina-scaled resolution | Not physical pixels—reports "CSS pixels" accounting for high DPI |
| Linux | Varies by desktop environment | Usually reports logical resolution; behavior depends on DE settings |
screen.width typically remains the width in portrait mode across all orientations in many browsers)All modern browsers (Chrome, Firefox, Safari, Edge) report screen resolution consistently using the same standard. However:
screen.width/height) differs from window size (window.innerWidth/innerHeight). Screen resolution is the full monitor size; window size is just the browser viewport.
Screen resolution is one of the most effective fingerprinting attributes. The combination of width and height creates a highly distinctive identifier.
While common resolutions like 1920×1080 are shared by many users, the distribution is fragmented across dozens of resolution combinations. Less common resolutions (like specific laptop resolutions or ultra-wide monitors) can uniquely identify you among thousands of users.
Unlike cookies or IP addresses, your screen resolution rarely changes. Most users keep the same monitor for years, making this a persistent identifier.
Screen resolution alone might not uniquely identify you, but when combined with:
The combination creates a nearly unique fingerprint.
An advertising network embeds trackers on multiple websites. Even if you block cookies, they can recognize you across sites by your screen resolution combined with 5-10 other fingerprint attributes.
You visit a website in normal mode, then return in incognito mode. The site recognizes you by matching your screen resolution, timezone, fonts, and other hardware attributes—completely bypassing incognito protection.
You create a second "anonymous" account on a platform. The platform detects it's you by matching your device fingerprint (including screen resolution), potentially violating your privacy or platform policies.
Research by EFF's Panopticlick project found that screen resolution alone provides approximately 4-5 bits of identifying information, meaning it narrows you down to roughly 1 in 16-32 users. Combined with other attributes, this becomes much more identifying.
Some fingerprinting protection extensions attempt to spoof screen resolution, but this is difficult to do consistently without breaking websites.
How it works: Reports standardized fake resolutions regardless of your actual screen
Pros:
Cons:
Strict Fingerprinting Protection: Rounds resolution to common values and adds slight randomization
Trade-off: Less effective than Tor but more usable for everyday browsing
Not Recommended: Running your display at non-native resolution degrades image quality and doesn't provide meaningful privacy benefits.
If purchasing a new monitor, choosing a very common resolution (like 1920×1080) makes you less distinctive than using ultra-wide or unusual resolutions. However, this is a minor factor.
For most users, the privacy cost of exposing screen resolution is acceptable given the web usability benefits. Focus on:
For everyday browsing: Use a privacy-respecting browser (Firefox, Brave) with tracker blocking. For sensitive activities: Use Tor Browser, which completely protects against resolution fingerprinting.