45M for the downloaded DMG file; 387M of extracted/mounted data; 314M in the Contents/Frameworks directory (which is where Electron is); 73M in the Contents/

45M for the downloaded DMG file; 387M of extracted/mounted data; 314M in the Contents/Frameworks directory (which is where Electron is); 73M in the Contents/Resources directory (which is where the application is); 73M is actually the size of the "Contents/Resources/app/node_modules" directory :D