Choosing an image format is not simply a matter of picking the newest option or the smallest file. Start with the job: does the image need transparency, is it a photograph or flat artwork, will it be edited again, and where will it be published?
Saving the same image as PNG, JPEG, and WebP changes how its pixel data is encoded and, for lossy formats, how much information is discarded. This is more than renaming a file extension, so every export needs a visual check.
Start with what each format is designed to do
PNG uses lossless compression and supports transparent backgrounds, which makes it dependable for logos, icons, interface captures, and sharp text. JPEG has no transparency but usually handles photographs with complex colour changes at a practical file size. WebP supports lossy and lossless modes as well as transparency, giving it a broad range of web uses. This tool does not expose a separate lossy or lossless WebP switch; the browser chooses the encoding mode.
The current PolishTools image resizer and cropper does not accept GIF input or animated PNG and WebP files.
| Format | Transparency | Common fit | Watch for |
|---|---|---|---|
| PNG | Yes | Logos, icons, sharp text, UI captures | Large files for photographs |
| JPEG | No | Photos with complex colour and texture | Blocking and smearing at low quality |
| WebP | Yes | Web photos and transparent artwork | Compatibility with the rest of your workflow |
Compare JPEG and WebP for photographs
PNG can encode a photograph without lossy compression, but the resulting file is often much larger than needed for the web. For a published photo, export comparable JPEG and WebP versions, then look at both detail and file size.
Smooth skies, hair, foliage, and the edges of small text tend to reveal compression problems early. Do not judge from the byte count alone. Check the image at its intended display size and at 100% scale.
PNG is straightforward for transparency and hard edges
PNG is predictable for a transparent logo or a screenshot with crisp boundaries. Converting that artwork to JPEG removes transparency and can add visible smearing around small lettering and areas of flat colour.
WebP can also preserve transparency and may reduce the file size. Keep a PNG or vector master, however, and create the final WebP from that master rather than repeatedly applying lossy compression to an earlier export.
Quality numbers are not equivalent
JPEG quality 80 and WebP quality 80 do not promise the same visual result. The value is a relative instruction passed to each encoder, and a suitable setting for one image may not suit another.
Browser encoder implementations can also produce different file sizes and fine detail from the same source and settings. If the publishing rule is strict, such as “under 200 KB,” export in the browser you plan to use and inspect the final file.
- Resize the source to the required pixel dimensions first.
- Export one JPEG and one WebP version.
- Compare them at actual display size and at 100%.
- Use the smaller file only when its visible quality is still acceptable.
Account for re-encoding and missing metadata
Every export creates a new file. Saving a JPEG as JPEG again is not a simple copy and can add another generation of lossy compression. When you need a new size, return to the best available source rather than reusing an already compressed derivative.
The canvas-based export may remove EXIF camera data, location, orientation information, and some colour profiles. That can be useful for a public image, but keep the original when you need a shooting record, archival quality, or managed print colour.
Example: choose a format for a blog cover photo
You have a 2400×1600 JPEG photograph and need a 1200×800 cover image while balancing file size and fine detail.
Steps
- Open the photo in the PolishTools image resizer and cropper, then set it to 1200×800 with the ratio locked.
- Export a JPEG, note its file size, and inspect the edges of foliage and hair.
- Export a WebP at the same dimensions and inspect the same areas.
- Compare both files at the size used by the article card and at 100% scale.
- Among the formats accepted by your publishing system, choose the smaller result that shows no distracting damage.
Result
The choice is based on the actual output rather than matching quality numbers. The export may no longer contain the camera metadata, so retain the source file.
Frequently asked questions
Is WebP always smaller than JPEG?
No. The image content, dimensions, quality setting, and browser encoder all affect the result. Export both at the same size when the difference matters.
Can I save a logo as JPEG?
You can if it has no transparency and minor edge artefacts are acceptable, but PNG or SVG is usually a better fit. JPEG damage is easy to see around small text and flat colours.
Does changing .png to .webp convert the image?
No. That only renames the file while leaving its internal data unchanged. A converter must decode and re-encode the image.