Window.devicePixelRatio

- WD

Read-only property that returns the ratio of the (vertical) size of one physical pixel on the current display device to the size of one CSS pixel.

IE

  1. 5.5 - 10: Not supported
  2. 11: Supported

Edge

  1. 12 - 79: Supported
  2. 80: Supported

Firefox

  1. 2 - 17: Not supported
  2. 18 - 72: Supported
  3. 73: Supported
  4. 74 - 75: Supported

Chrome

  1. 4 - 79: Supported
  2. 80: Supported
  3. 81 - 83: Supported

Safari

  1. 3.1 - 12.1: Supported
  2. 13: Supported
  3. TP: Supported

Opera

  1. 9 - 11.5: Not supported
  2. 11.6 - 65: Supported
  3. 66: Supported

iOS Safari

  1. 3.2 - 13.1: Supported
  2. 13.2: Supported
  3. 13.3: Supported

Opera Mini

  1. all: Supported

Android Browser

  1. 2.1 - 4.4.4: Supported
  2. 80: Supported

Blackberry Browser

  1. 7: Supported
  2. 10: Supported

Opera Mobile

  1. 10 - 11.5: Not supported
  2. 12 - 12.1: Supported
  3. 46: Supported

Chrome for Android

  1. 80: Supported

Firefox for Android

  1. 68: Supported

IE Mobile

  1. 10: Not supported
  2. 11: Supported

UC Browser for Android

  1. 12.12: Supported

Samsung Internet

  1. 4 - 9.2: Supported
  2. 10.1: Supported

QQ Browser

  1. 1.2: Supported

Baidu Browser

  1. 7.12: Supported

KaiOS Browser

  1. 2.5: Supported

As the page is zoomed in the number of device pixels that one CSS pixel covers increases, and therefore the value of devicePixelRatio will also increase.

Resources:
MDN Web Docs - devicePixelRatio