Use PDF when an image needs to act like a document
JPG, PNG, WebP, GIF, TIFF, and AVIF are image formats. PDF is usually easier when the destination expects a document, page, receipt, signed form, worksheet, or application attachment.
Convert image files to PDF when a portal asks for PDF, when you need stable page layout, or when an email recipient should open one document instead of separate image files.
Choose the source format by what you have
Use JPG to PDF for normal photos and camera scans. Use PNG to PDF for screenshots and images with sharp text. Use WebP or AVIF to PDF when a modern web image needs to become a more accepted document file.
Use TIFF to PDF for scanned pages and archive images. Use GIF to PDF only when you need a still document copy, because PDF conversion will not preserve animation as a normal moving image.
Check the result before submitting
Open the PDF and review page size, rotation, margins, text readability, and file size. A photo can look acceptable in a gallery but still be hard to read once it becomes a document page.
Keep the source image until the destination accepts the PDF, especially for school, job, government, financial, or client uploads.
When not to use PDF
If a site specifically asks for JPG or PNG, keep the file as an image. If the goal is a lightweight web image, WebP or JPG may be better than PDF. Use PDF when the output needs to behave like a document.