Inlining images as Base64 adds about 33% size, but can still pay off for small assets

Base64 encoding turns binary image data into text, which makes the file roughly one third larger. Inlining is worthwhile for small, critical images like logos and icons, since it removes a network request and avoids blocked remote images in email. For large photos, the inflated size is re-downloaded with every page load and cannot be cached separately, so a linked file is usually better. A common rule of thumb is to inline images under about 10KB, weigh images between 10KB and 50KB case by case, and link anything larger. Conversion can be done entirely in the browser using the FileReader API, without uploading files to a server.