The short answer
Use JPG for photographs and anything going into a form. Use PNG for screenshots, logos, diagrams and anything needing a transparent background. Use WebP on your own website. Convert HEIC to JPG before sending it to anyone.
That covers most situations. The reasoning behind it is worth understanding, because it explains the mistakes people make.
Lossy and lossless
This single distinction explains nearly everything else. JPG, WebP and HEIC are normally lossy: they achieve small files by permanently discarding detail the eye is unlikely to notice. PNG is lossless: it stores the image exactly, and is correspondingly larger.
Lossy compression is not a defect. A photograph contains far more information than anyone can perceive, and discarding the excess is how a 30-megapixel image becomes a 2MB file. The important consequence is that the loss is permanent and it accumulates. Saving a JPG, editing it, and saving again degrades it a little further each time.
JPG
Dating from 1992 and still the default for photographs everywhere. Its compression is designed around how human vision works, discarding fine colour variation the eye barely registers while preserving the brightness detail it notices.
Use it for: photographs, scanned documents, and anything being uploaded to a form. It is the one format you can rely on being accepted absolutely everywhere.
Avoid it for: screenshots of text, logos, line drawings and diagrams. JPG handles sharp edges badly, producing a faint halo of noise around lettering that is immediately obvious once you notice it. It also cannot store transparency, so a see-through background becomes solid.
PNG
Lossless, with full transparency support. Because it stores everything exactly, quality settings do not apply, and files are considerably larger than JPG for photographic content — commonly five to ten times.
Use it for: screenshots, particularly of text; logos and graphics with flat colour; diagrams and charts; anything needing a transparent background; and any image you will edit repeatedly, since repeated saving does not degrade it.
Avoid it for: photographs you need to send somewhere. It works, but the file will be needlessly large for no visible benefit.
One misconception worth correcting: converting a JPG to PNG does not restore quality. The detail was already discarded. All you get is a larger file containing exactly the same visible information.
WebP
Developed by Google and now supported by every current browser. It offers both lossy and lossless modes, supports transparency, and is typically 25 to 35 percent smaller than JPG at equivalent quality.
Use it for: images on your own website, where the file size saving translates directly into faster loading.
Avoid it for: anything you are sending to someone else or uploading to a form. Support in browsers is universal, but support in older desktop software, some email clients and many upload validators is not. A form that accepts JPG and PNG will frequently reject WebP.
HEIC
Apple's implementation of the HEIF standard, and the default on iPhones since iOS 11. It borrows compression techniques from modern video encoding, fitting roughly the same photograph into half the space of a JPG.
It also stores things JPG cannot: multiple frames in one file, which is how Live Photos work; depth information used for portrait mode; and greater colour depth.
Use it for: keeping your own photographs on Apple devices, where it saves considerable storage at no visible cost.
Avoid it for: sending to anyone. Windows support depends on codecs Microsoft licenses rather than includes, so the same file opens for one person and not another. Upload forms reject it almost universally. Our HEIC converter handles the conversion, and none of the extra information survives it — a Live Photo becomes a single still.
Size comparison
The same twelve-megapixel photograph, saved in each format at ordinary quality settings:
| Format | Typical size |
|---|---|
| HEIC | 1.5 MB |
| WebP | 2.2 MB |
| JPG | 3.2 MB |
| PNG | 18 MB |
Those ratios shift with subject matter. A screenshot of text reverses the picture entirely: PNG might be 200KB while JPG produces a larger, visibly worse file.
Choosing by what you are doing
- Uploading to any form — JPG. No exceptions worth making.
- Emailing photographs — JPG, compressed to something reasonable first.
- Sharing a screenshot — PNG, for readable text.
- Putting images on a website — WebP, with a JPG fallback if you support older software.
- Archiving your own photographs — keep the originals in whatever the camera produced.
- Anything needing transparency — PNG, or WebP for web use.
The format converter handles all four, and the image compressor takes a target size directly if a form has given you a limit in kilobytes.