JPG vs PNG vs WebP: Which Format Should You Use?
A plain-language comparison of the three common image formats and which one to pick for forms, documents, signatures and the web.
Image formats store the same picture in different ways, and choosing the wrong one can make a file several times larger than it needs to be — or get it rejected by a form that only accepts one type. Here is what each format is good at.
JPG (JPEG)
JPG is designed for photographs. It uses "lossy" compression, discarding fine detail the eye does not notice, which makes photo files very small. It is accepted almost everywhere and is the best choice for passport photos, ID photos and any form that asks for a photo under a size limit. Its weaknesses: it cannot store transparency, and repeated saving at low quality gradually adds visible artifacts.
PNG
PNG is "lossless" — it keeps every pixel exactly. That is perfect for screenshots, diagrams, logos and text, and it supports transparent backgrounds. For photographs, however, PNG files are typically 5–10 times larger than a good JPG, so they are a poor choice when a form has a KB limit. To reach small targets with PNG, PhotoSize reduces the number of colours, which can make photos look posterised.
WebP
WebP is a modern format that can be lossy like JPG or lossless like PNG, and supports transparency. At the same visual quality a lossy WebP is usually 25–35% smaller than JPG. Many websites use it, but some older systems and government portals do not accept it yet.
| JPG | PNG | WebP | |
|---|---|---|---|
| Best for | Photos | Screenshots, logos, text | Web images |
| File size for photos | Small | Large | Smallest |
| Transparency | No | Yes | Yes |
| Accepted by forms | Almost always | Often | Sometimes |
Quick recommendations
- Photo for an application form: JPG.
- Signature that will be placed on a document: PNG with a transparent background.
- Screenshot of a document or receipt: PNG (or JPG if there is a size limit).
- Images for your own website: WebP.
When converting a transparent PNG to JPG, the transparent areas must be filled with a colour. PhotoSize uses white by default, and you can choose another colour in the Convert tool.