CSS3 Box-sizing

- WD

Method of specifying whether or not an element's borders and padding should be included in size units

Chrome

  1. ✅ 4 - 9: Supported
  2. ✅ 10 - 154: Supported
  3. ✅ 155: Supported
  4. ✅ 156 - 158: Supported

Edge

  1. ✅ 12 - 154: Supported
  2. ✅ 155: Supported

Safari

  1. ✅ 3.1 - 5: Supported
  2. ✅ 5.1 - 26.6: Supported
  3. ✅ 27: Supported
  4. ✅ 27.1 - TP: Supported

Firefox

  1. ✅ 2 - 28: Supported
  2. ✅ 29 - 157: Supported
  3. ✅ 158: Supported
  4. ✅ 159 - 161: Supported

Opera

  1. ❌ 9: Not supported
  2. ✅ 9.5 - 134: Supported
  3. ✅ 135: Supported

IE

  1. ❌ 5.5 - 7: Not supported (but has polyfill available)
  2. ✅ 8 - 10: Supported
  3. ✅ 11: Supported

Chrome for Android

  1. ✅ 155: Supported

Safari on iOS

  1. ✅ 3.2 - 4.3: Supported
  2. ✅ 5 - 26.6: Supported
  3. ✅ 27.0: Supported
  4. ✅ 27.1 - 27.2: Supported

Samsung Internet

  1. ✅ 4 - 29: Supported
  2. ✅ 30: Supported

Opera Mini

  1. ✅ all: Supported

Opera Mobile

  1. ✅ 10 - 12.1: Supported
  2. ✅ 80: Supported

UC Browser for Android

  1. ✅ 15.5: Supported

Android Browser

  1. ✅ 2.1 - 3: Supported
  2. ✅ 4 - 4.4.4: Supported
  3. ✅ 155: Supported

Firefox for Android

  1. ✅ 158: Supported

QQ Browser

  1. ✅ 14.9: Supported

Baidu Browser

  1. ✅ 13.52: Supported

KaiOS Browser

  1. ✅ 2.5: Supported
  2. ✅ 3: Supported

Firefox versions before 57 also supported the padding-box value for box-sizing, though this value was been removed from the specification and later versions of the browser.

Resources:
CSS Tricks
MDN Web Docs - CSS box-sizing
Polyfill for IE
WebPlatform Docs
Blog post