Screen Resolution Simulator

A screen resolution simulator reports the screen's actual width and height, the viewport's width and height, device pixel ratio, and color depth automatically on load, updating live whenever the browser window is resized. Device presets or custom dimensions then preview how a page renders at a size other than the current display, without needing a second physical device for every resolution being checked.

Device presets load common dimensions covering phones, tablets, laptops, and desktop monitors from HD through 5K. A custom width and height can also be entered directly, from 100 to 7680 pixels wide and 100 to 4320 pixels tall, covering everything from a small phone screen to an 8K display. An orientation toggle swaps width and height between landscape and portrait, simulating a device being rotated.

A full URL beginning with https loads a live website inside the simulation frame at the specified dimensions; left blank, the frame shows a placeholder describing the simulated dimensions instead. The frame itself scales proportionally to fit the browser window while preserving the simulated aspect ratio, so a 4K frame remains visibly 4K-shaped even though it renders smaller on screen.

A table of common screen resolutions, organized by device category and listing each one's aspect ratio, sits alongside the simulator as a quick reference when choosing which size to test next.

Testing how a website or web application renders across different screen sizes is a critical step in modern web development. Browser-based simulation eliminates the need to own dozens of physical devices and provides a fast preview of any resolution. The scenarios below illustrate where this approach adds significant value.

• Responsive Web Design: Verify CSS breakpoints trigger correctly at common viewport widths such as 768, 1024, 1366, and 1920 pixels. Confirm navigation menus collapse, images resize, and grid layouts reflow at each breakpoint.
• Mobile-First Development: Preview a site at mobile resolutions like 375 by 667 or 390 by 844 pixels to confirm touch targets are large enough, text remains readable, and horizontal scrolling does not occur.
• Client Presentations: Demonstrate how a website appears on specific devices, such as the iPad Pro at 1024 by 1366 or a 4K desktop at 3840 by 2160, without needing those devices on hand.
• Quality Assurance Testing: Cycle through every resolution in a test matrix using the device presets and document layout issues at each size.
• Email Template Testing: Preview HTML email templates at common email client viewport widths to verify tables, images, and text blocks render correctly in narrow and wide reading panes.
• Digital Signage and Kiosks: Simulate non-standard display resolutions used in kiosks and embedded displays by entering custom width and height values that match the target hardware.
• Ultrawide and Multi-Monitor Layouts: Test how content stretches or centers on ultrawide monitors at 3440 by 1440 or 5K displays at 5120 by 2880 to ensure layouts do not break at extreme widths.
• SEO and Core Web Vitals: Confirm above-the-fold content and largest contentful paint elements display correctly at the viewport sizes used for mobile and desktop indexing.