JPG, PNG, WebP, HEIC, and AVIF: which should I use?
Use the format the receiving website accepts. JPG is broadly useful for photos, PNG supports transparency and lossless encoding, and WebP can be efficient where accepted. Converting a file does not restore detail already lost.
Reviewed
Match the format to the requirement
| Format | Useful for | Main consideration |
|---|---|---|
| JPG / JPEG | Photos and upload forms that require JPEG. | Lossy; cannot preserve transparency. |
| PNG | Sharp graphics, screenshots, alpha. | Lossless encoding can produce large photo files. |
| WebP | Web imagery and destinations that accept it. | Do not assume every form supports it. |
| HEIC / HEIF | Source photos from compatible devices. | Decode support varies; convert when the receiver requires JPG. |
| AVIF | Efficient imagery in compatible software. | FileFit decoding and encoding depend on browser capabilities. |
Changing an extension is not conversion
Renaming a file from .png to .jpg leaves the original encoded bytes unchanged. FileFit decodes the source and uses an encoder to create a real output file. It checks the returned MIME type instead of trusting a requested extension.
If AVIF encoding is unsupported, FileFit reports the limitation rather than saving another format under an AVIF name. HEIC input uses a locally loaded libheif decoder. Unusual source variants can still fail.
Keep transparency and detail intentionally
A JPG cannot store alpha transparency. In image conversion, choose the background color under Advanced options before exporting to JPG. For Images to PDF, transparent areas use white because source images are embedded as JPEG.
A JPG converted to PNG still contains the decoded JPG artifacts. A lossy format converted repeatedly can lose more detail. Retain the source and choose the format once where possible.
File size is a result, not a format promise
WebP or JPG may be smaller for a photo, but no format wins for every file. Check actual bytes. If a conversion creates a larger file, the result card shows an increase accurately.
Re-encoding removes metadata. Animated images and multiple images in one HEIC container are not exported as full sequences. Inspect the downloaded output in the software or form where you intend to use it.
Try the relevant tools
Sources and implementation
Tool behavior is documented in How FileFit works. Examples are instructional, not a promise about every file. Report a correction.