Formats
PNG vs WebP vs JPEG: Which Format Should You Use?
Pick the format before you pick the quality setting. The format determines what the encoder is allowed to throw away, whether transparency survives, and which applications will open the file at all. The three formats most people need are PNG, WebP, and JPEG, and they are not interchangeable.
The short version
- JPEG for photographs that need maximum compatibility.
- WebP for photographs and graphics on the web, when the destination accepts it.
- PNG for screenshots, logos, line art, and anything that needs lossless pixels or transparency.
- Never convert a JPEG to PNG to improve quality. The detail is already gone; PNG only preserves the absence of it in a larger file.
How each format stores an image
JPEG divides the image into 8×8 blocks, converts color to a luminance and two chroma channels, and quantizes the result. Quantization is lossy and controlled by the quality setting. Most encoders also subsample chroma, storing color at half resolution because human vision is less sensitive to color detail than to brightness. JPEG has no alpha channel. Saving the same image repeatedly at moderate quality produces generation loss: each pass re-quantizes data that was already approximated.
PNG applies lossless filters to each scanline and compresses the result with DEFLATE. Every pixel is preserved exactly. PNG supports an alpha channel, so soft shadows and cut-out subjects keep clean edges. The cost is size: photographic noise is close to random data, which DEFLATE cannot compress well. A photograph saved as PNG is often several times larger than a high-quality JPEG and looks no better.
WebP has two modes. Lossy WebP uses block prediction similar in spirit to a video codec; lossless WebP uses its own compression. Both support alpha. For photographs, lossy WebP is typically smaller than JPEG at a comparable visual quality. For flat graphics, lossless WebP is often smaller than PNG. It is not magic: on very small images, format overhead can make PNG the smaller file.
Side-by-side
| PNG | JPEG | WebP | |
|---|---|---|---|
| Compression | Lossless | Lossy | Lossy or lossless |
| Transparency | Yes | No | Yes |
| Best subject | Text, logos, screenshots, line art | Photographs | Photographs and web graphics |
| Re-saving the same file | No quality loss | Accumulating loss | Lossy mode accumulates loss |
| Typical file size for a photo | Largest | Small to medium | Smallest |
| Browser support | Universal | Universal | All current major browsers |
| Metadata after a browser re-encode | Dropped | Dropped | Dropped |
Transparency is where conversions go wrong
JPEG cannot store an alpha channel. When a transparent PNG is converted to JPEG, the transparent pixels must become some solid color. Browser canvas encoders usually produce black. That is fine for a photo with no transparency and disastrous for a logo with a transparent background.
The format converter handles this explicitly: when you choose JPEG as the output, you can set the color that fills transparent areas. Pick white for a document, or match the background of the page where the image will appear. If you forget, you get a black rectangle where the transparency used to be.
The reverse direction has no such problem but no benefit either. Converting JPEG to PNG preserves every pixel of the already-degraded image and usually makes the file larger. Transparency cannot be recovered because it was never stored.
When WebP is the wrong answer
WebP support is broad, but the destination matters more than the browser. Some content management systems reject uploads by extension. Some print workflows, older desktop publishing tools, and a few email clients will not open it. Marketplaces and job portals often publish an explicit list of accepted types, and WebP is frequently missing.
Check the destination’s rules before converting a batch. If the list says JPG or PNG only, use JPEG for photographs and PNG for graphics. If there is no list and the image is going on a web page you control, WebP is usually the better default.
There is also a quality trap: converting an existing JPEG to WebP does not restore detail. It re-encodes an already compressed image. The result may be smaller, but it will not be sharper than the JPEG you started with. Start from the original whenever one exists.
Metadata does not survive a browser conversion
A camera JPEG can carry EXIF fields such as capture date, camera model, exposure, GPS coordinates, and copyright. PNG and WebP have their own metadata chunks. A canvas-based conversion decodes the pixels and encodes a new file, so those fields are not copied. The image may come out upright because orientation is applied during decoding, but the tag itself is gone, along with the GPS data.
For privacy, that is often desirable. For an archive or a photo delivered to a client who expects embedded copyright, it is a loss. Keep the original if metadata matters, and treat the converted copy as a delivery file. The EXIF rotation guide covers this trade-off in more detail.
Convert a batch in the browser
- Open the format converter.
- Drop in the files, or click the drop zone to choose them. The tool accepts batches and processes files locally.
- Choose the output format: PNG, JPG, or WebP.
- If the output is JPEG and any source has transparency, set the background color used to fill transparent pixels.
- Convert, then check a representative file at 100 percent zoom before downloading the rest.
- Download individual results or the whole set as a zip.
The same 50 MB per-file and 40-megapixel limits apply here as elsewhere on the site. They protect the browser tab, not a server quota.
Choosing under pressure
If you have ten seconds to decide: photograph on a website, use WebP; photograph going to a form or a client, use JPEG; screenshot or logo, use PNG. If the file must be small and the destination accepts WebP, convert to WebP and compare one file against the JPEG before committing to the batch.
Format choice is not a quality setting. It is a decision about what the file is allowed to contain. Get it right first, then use the compressor to hit a byte target within that format.