OS Details

Samsung Galaxy S20 Ultra has been launched in March 2020.
Samsung Galaxy S20 Ultra have Android 10.0 ; One UI 2.5

Screen Dimensions

Samsung Galaxy S20 Ultra screen size is 6.9 inch with ~ 89.9% body ratio of actual device size. Physical dimensions for Samsung Galaxy S20 Ultra device is 6.57 x 2.99 x 0.35 INCH or ( 166.9 x 76 x 8.8 MM).

Displaying of Units are in this order "Height x Width x Thickness"

Screen Pixel Density and CSS Pixel Ratio

"Pixel" is smallest unit/element of any display.

The total number of pixels that fit into an inch is referred to as "Screen Density" or "Pixel Density" and it measured as "Pixels Per Inch".
Pixel Desnsity have limits to display Pixels Per Inch depends on different screen sizes. When number of pixels per inch increases than it's screen-size limit, the Display resolution will increase but actual device width/height in pixels remain same. Actual device pixels are known as Device Independent Pixels or CSS Pixel Ratio.

Samsung Galaxy S20 Ultra resolution is 1440 x 3200 ^PX with ~ 511 pixel desnsity.
Samsung Galaxy S20 Ultra viewport size is 412 x 915 ^PX with ~ 146 actual pixel density, which means it have 3.5 xxxhdpi display pixel density.

Screen Resolution and Viewport

The sum of pixels which are displaying on a device is called as "Screen Resolution". and sum of actual pixels of any device is reffered to as "Viewport".

Samsung Galaxy S20 Ultra have 6.9" physical screen size and its resolution is about 1440 x 3200 Pixels with approximately 511 PPI pixel density. Samsung Galaxy S20 Ultra has viewport size 412 x 915 Pixels and its pixel ratio is about 3.5.

For better understanding screen actual sizes, viewport sizes, display resolution and about their density click here.

CSS Media Queries

Samsung Galaxy S20 Ultra css media queries will help developers to write styles specifically for Samsung Galaxy S20 Ultra. Here are details:

Samsung Galaxy S20 Ultra Media Queries (In terms of Mobile only)

@media only screen and (min-width: 412px) and (max-width: 767px) { /* Your Styles... */ }

Samsung Galaxy S20 Ultra Min-Width Media Queries

@media only screen and (min-width: 412px) { /* Your Styles... */ }

Samsung Galaxy S20 Ultra Min-Height Media Queries

@media only screen and (min-height: 915px) { /* Your Styles... */ }

Samsung Galaxy S20 Ultra Landscape Media Queries

@media only screen and (min-width: 915px) and (orientation: landscape) { /* Your Styles... */ }

Samsung Galaxy S20 Ultra Portrait Media Queries

@media only screen and (min-width: 412px) and (orientation: portrait) { /* Your Styles... */ }

Samsung Galaxy S20 Ultra Device Width Media Queries

@media only screen and (min-device-width: 412px) and (orientation: portrait) { /* Your Styles... */ }
@media only screen and (min-device-width: 915px) and (orientation: landscape) { /* Your Styles... */ }

Samsung Galaxy S20 Ultra Retina Media Queries

@media
  only screen and (-webkit-min-device-pixel-ratio: 3.5),
  only screen and (   min--moz-device-pixel-ratio: 3.5),
  only screen and (     -o-min-device-pixel-ratio: 3.5/1),
  only screen and (        min-device-pixel-ratio: 3.5),
  only screen and (                min-resolution: 511dpi),
  only screen and (                min-resolution: 3.5dppx) { 
    /* Retina styles here */
}
                                

Retina is actually based upon device pixel ratio. Devices mostly have 2x or 3x display so you can use general retina media queries to display high resolution content on all kind of devices. Retina 2x and Retina 3x media queries given below:

Retina 2x Media Query (for all 2x resolution supported devices)

@media
  only screen and (-webkit-min-device-pixel-ratio: 2),
  only screen and (   min--moz-device-pixel-ratio: 2),
  only screen and (     -o-min-device-pixel-ratio: 2/1),
  only screen and (        min-device-pixel-ratio: 2),
  only screen and (                min-resolution: 192dpi),
  only screen and (                min-resolution: 2dppx) { 
    /* Retina styles here */
}
                                

Retina 3x Media Query (for all 3x resolution supported devices)

@media
  only screen and (-webkit-min-device-pixel-ratio: 3),
  only screen and (   min--moz-device-pixel-ratio: 3),
  only screen and (     -o-min-device-pixel-ratio: 3/1),
  only screen and (        min-device-pixel-ratio: 3),
  only screen and (                min-resolution: 384dpi),
  only screen and (                min-resolution: 3dppx) { 
    /* Retina styles here */
}
                                

Samsung Galaxy S20 Ultra Specifications

• Launch Date March 2020
• Android 10.0
• Physical Screen Size 6.9 INCH
• Resolution 1440 x 3200 PX
• Viewport Size 412 x 915 PX
• Pixel Density 511 PPI
• Device-Independent Pixels 146 PPI
• Pixel Ratio 3.5 xxxhdpi
• Width 1440 PX
• Height 3200 PX
• Device Width 412 PX
• Device Height 915 PX
• Dimensions 166.9 x 76 x 8.8 mm (6.57 x 2.99 x 0.35 in)
• Weight 220 g - 7.76 oz