Samsung Galaxy S21 Ultra: CSS viewport of 360 × 800 px, resolution and responsive test

Why test your site on Samsung Galaxy S21 Ultra?

CSS viewport resolution of Samsung Galaxy S21 Ultra

This is the width your CSS considers. All your breakpoints and media queries compare to this value, not the number of physical pixels on the panel.

The height remains indicative: Safari, Chrome, and other mobile browsers reduce the visible area with their address bar, which folds on scroll.

Be cautious when analyzing your statistics: some tools only report the manufacturer resolution, never the CSS viewport presented here.

Pixel density of Samsung Galaxy S21 Ultra

The device pixel ratio of Samsung Galaxy S21 Ultra is 4. Your images should therefore be exported 4 times larger than their display size, otherwise they will appear softened on this screen.

Manufacturer resolution of Samsung Galaxy S21 Ultra

This is the actual number of pixels on the panel. This value does not affect your layouts, but it's the one reported by technical specifications and most analytics tools.

• 1440 pixels in width
• 3200 pixels in height
• 516 pixels per inch (ppi)
• 6.8 inches diagonal, or 17.3 cm
• Screen ratio of 20:9

User-Agent of Samsung Galaxy S21 Ultra

This string is what the browser of Samsung Galaxy S21 Ultra sends. It is useful for your automated tests, reading your server logs, and server-side detection.

Mozilla/5.0 (Linux; Android 16; SM-G998B) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.6778.260 Mobile Safari/537.36

Media queries and code snippets for Samsung Galaxy S21 Ultra

These snippets are generated from the exact characteristics of Samsung Galaxy S21 Ultra. Copy them directly into your stylesheet or configuration.

@media only screen and (min-width: 360px) and (max-width: 799px) {
  /* Samsung Galaxy S21 Ultra */
}

@media only screen and (-webkit-min-device-pixel-ratio: 4),
       only screen and (min-resolution: 384dpi) {
  /* High-density images and icons */
}

// tailwind.config.js
module.exports = {
  theme: {
    screens: {
      'samsung-galaxy-s21-ultra': '360px'
    }
  }
}

const isDeviceWidth = window.matchMedia('(min-width: 360px)').matches;
const isHighDensity = window.devicePixelRatio >= 4;

<meta name="viewport" content="width=device-width, initial-scale=1">

Free Samsung Galaxy S21 Ultra simulator

Mobile FIRST includes Samsung Galaxy S21 Ultra: your page displays in a viewport of 360 x 800 pixels, with the model's User-Agent, touch events, and scrolling behavior of a real mobile.

This is where the difference with Chrome DevTools' responsive mode is seen: DevTools resizes a window, the extension replicates the device's browser and allows exporting shareable screenshots and videos.

1. 01 Install the extension — Add Mobile FIRST to Chrome, Firefox, or Edge. Installation is free and requires no account.
2. 02 Open the page to test — Go to the URL to check, including a local address like localhost:3000.
3. 03 Choose Samsung Galaxy S21 Ultra — Select Samsung Galaxy S21 Ultra from the list of devices. The viewport switches to 360 x 800 pixels, and the mobile User-Agent is applied.
4. 04 Check rendering — Scroll, change orientation, test your forms, then capture an image or video to share.

Comparison with similar models

The neighboring formats of Samsung Galaxy S21 Ultra are the ones to test right after, as they reveal poorly placed breakpoints.

Samsung Galaxy S21 Ultra PNG mockup

To present a mockup or capture in a realistic frame, the transparent mockup of Samsung Galaxy S21 Ultra is available for free download.

Frequently asked questions about Samsung Galaxy S21 Ultra

Updated on August 15, 2026