Online forms often specify both an accepted file type and a maximum file size. Start by making a copy of the original image so you can safely experiment without losing the full-quality version.
Read the upload requirements first
Check whether the form asks for JPG, PNG or another format, and note any required width, height or maximum KB/MB limit. If dimensions are specified, resize to those dimensions before applying heavy compression.
Keep the aspect ratio when possible
Keeping the original aspect ratio prevents faces, documents and other subjects from looking stretched. If the form requires an exact shape, crop a copy in a suitable editor before resizing.
Reduce file size gradually
After resizing, compress a photographic image at a moderate quality and inspect the result. If the form has a strict target such as 200 KB, use the TheTecTricks Exact KB tool and leave a small safety margin below the stated limit.
Check the final file
Open the downloaded copy before uploading. Make sure important text remains readable and that the file extension matches what the form accepts.