Get Sizekin.

iPhone or iPad

Open this site in Safari. Tap Share → Add to Home Screen, then Add. If offered, leave Open as Web App switched on.

Android

Open this site in Chrome. Open the browser menu and choose Install app or Add to Home screen, then follow the prompt.

Computer

In Chrome or Edge, use the install icon in the address bar or the browser’s app menu. In a supported version of Safari on Mac, choose File → Add to Dock.