Choose a format from recipient requirements and whether transparency must remain, rather than assuming one format is always smaller. Photos, lecture diagrams, transparent logos and submission forms have different needs. Renaming an extension does not convert the file contents.
Compare JPEG, PNG and WebP by requirement
| Requirement | Starting choice | Check |
|---|---|---|
| Transparent logo or diagram | PNG | Alpha, readable text and lines |
| Transparent web asset | Compare PNG and WebP at equal dimensions | Destination compatibility, transparency and bytes |
| Form explicitly requires JPEG | JPEG | White compositing and re-encoding artifacts |
| Fine lettering in screenshots or scientific figures | Inspect PNG first | Format alone does not guarantee an unchanged processing pipeline |
| Preserve animation | A different, animation-specific workflow | Canvas export here does not preserve motion |
JPEG has no alpha channel. PNG uses lossless compression. WebP supports alpha, but this interface has no lossless/lossy mode selector. For a dimension change, consult the resize decision table; for a different retained region, use the crop guide.
Once your requirements are clear
Check transparency and destination requirements first
Choose PNG for alpha or JPG for a JPEG-only destination. Keep the original and compare the output background and size.
Workflow: choose settings before selecting an image
- Open the Image Converter and select PNG, JPG or WEBP.
- For JPEG/WebP, choose quality from 0.1 to 1; the default is 0.9. PNG encoding does not use that quality parameter.
- Select or drop one image. Selection starts conversion automatically.
- Inspect dimensions and original/output sizes. Conversion alone does not resize width or height.
- Download and reopen the saved file. Selecting JPG for
sample.pngproducessample.jpg.
Changing a format button after conversion does not regenerate the displayed output. Select the file again after changing settings. This is a one-file workflow, without batch or ZIP export.
Compare outputs at the same dimensions
A 640×400 source remains 640×400 after format conversion. Compare actual encoded bytes and choose only the processing needed to meet requirements.
| Setting or number | Meaning | Does not mean |
|---|---|---|
| Quality 0.9 | Browser encoder quality parameter | 90% size or 90% reduction |
| 640×400px | 256,000 pixels | 256,000 bytes |
| Input up to 50MiB | 52,428,800 bytes | Guaranteed processing of any decoded dimensions |
| PNG to JPEG | Re-encoding into another type | Recovering lost detail |
We do not claim that every 2MB photo becomes a few hundred KB or that WebP always saves a fixed percentage. Content, prior compression, dimensions and browser encoding affect results. If output grows, compare the purpose of resizing or compression instead of adopting it automatically.
HEIC, animation and unsupported input
There is no dedicated HEIC decoder. If the OS/browser cannot decode an input, export a JPEG or PNG copy on the device using appropriate official guidance, such as Apple’s instructions.
Animated GIF/WebP is not preserved as animation. Exif/GPS data, color profiles, high bit depth and print-resolution metadata are not guaranteed to transfer. Keep originals and scientific measurement files separately. When the requested encoder is unsupported, the tool reports an error rather than labeling PNG bytes with the wrong extension.
Inspect the saved file before moving on
- For transparent assets, inspect the required alpha areas rather than judging only against a white page.
- For photos and diagrams, zoom in on lettering, edges, colors and the intended background.
- For submissions, check format, dimensions and actual size at the save location.
The implementation processes images in the browser without uploading the input. Page-loading requests, extensions, shared computers and storage security are separate concerns.
Once your requirements are clear
Save a file in the format your destination accepts
Select the format, select the image again and inspect the saved result. Favorite the tool to return next time.
Update and verification scope
On October 26, 2026 the Tools Hub editorial team compared the implementation and workflow. Small fixtures verified PNG/WebP transparency, JPEG white compositing, dimensions, format and downloads. This is not a universal size-reduction benchmark, HEIC compatibility guarantee or validation of medical/scientific pixel identity.
Compare the available tools and guides in the image category.
FAQ
What happens to transparency when PNG becomes JPEG?
JPEG has no alpha channel, so this tool composites transparent areas onto white. Choose PNG or a destination-supported WebP when transparency is required.
Do format or quality changes automatically regenerate the result?
No. Choose format and quality before selecting the image. After changing settings, select the same image again and check the new preview and downloaded file.
Is HEIC-to-JPEG conversion guaranteed?
No dedicated HEIC decoder is included. Decoding depends on the browser and OS. If loading fails, export a JPEG or PNG copy using an appropriate app on your device.
Will WebP always be smaller?
No. Content, dimensions and encoder settings can produce a larger file. Quality 0.9 means neither 90% of the original size nor a 90% reduction. Compare actual bytes and appearance at matched dimensions.
