PDF (Portable Document Format)
PDF is a page-based document format that renders identically everywhere, which is why forms and print shops demand it.
- File extension
- MIME type
- application/pdf
- Compression
- Lossless
- Transparency
- No
- Animation
- No
- Type
- Raster (pixels)
Where PDF files come from
Required by an application form, a print shop or an office workflow.
Universal. Every device on earth can open a PDF.
What PDF is good at
- Looks the same on every device, operating system and printer
- Combines many images into one tidy, ordered document
- The format almost every official form, application and print shop asks for
Where PDF falls short
- A document, not an image — you cannot edit the pixels afterwards
- Cannot be used as an image on a web page
- Transparency is flattened onto a white page
Should you use PDF?
Use it when the image must survive editing and re-saving without degrading, or when transparency matters. Avoid it for large photographs that only need to be viewed, where a lossy format will be a fraction of the size with no visible difference.
Convert to PDF
Frequently asked questions
What is PDF (Portable Document Format)?
PDF is a page-based document format that renders identically everywhere, which is why forms and print shops demand it. Universal. Every device on earth can open a PDF.
How do I open PDF files?
PDF is a container this site writes rather than reads. Most operating systems open it natively.
Is PDF lossy or lossless?
PDF is lossless — every pixel is stored exactly, and re-saving it repeatedly costs you nothing in quality. The trade-off is a larger file.
Does PDF support transparency?
No. PDF has no alpha channel, so transparent areas must be filled with a background colour when you convert into it. White is the usual choice.