How to use Image Converter
- 1Drop in one image, or up to 50 to convert as a batch
- 2Choose the output format
- 3Set the quality for JPG, WebP or AVIF
- 4Pick a background colour if transparency will be lost
- 5Download the result, or the batch as a ZIP
What Image Converter does
Image formats differ along three axes that matter: whether they discard data to save space, whether they can store transparency, and how widely they are supported. Every practical choice is a trade between those three, and there is no format that wins on all of them.
PNG keeps every pixel and supports transparency but is large for photographs. JPG is small for photographs and cannot store transparency at all. WebP and AVIF do both jobs better than either but are more recent, and BMP and ICO exist for specific technical purposes rather than general use. Knowing which axis you actually care about makes the choice straightforward.
When to use it
- Making images smaller for a web page
- Converting PNGs and JPGs to WebP typically saves 25–35% at the same visual quality, and every current browser reads it.
- Meeting an upload requirement
- Forms and portals frequently accept only JPG or PNG. Converting is faster than finding out which of your files are in some other format.
- Making a favicon
- ICO is the format browsers expect for a site icon, and it can hold several sizes in one file so the browser picks the right one.
- Preparing images for older software
- BMP is uncompressed and readable by essentially anything, which occasionally matters for legacy tools and embedded systems.
Image Converter settings explained
- PNG
- Lossless with full transparency support. The right choice for screenshots, logos, diagrams and anything with hard edges or an alpha channel. Large for photographs, because it stores photographic noise without discarding any of it.
- JPG
- The smallest widely supported option for photographs, with no transparency at all. Anything transparent is filled with the background colour you choose before encoding.
- WebP
- 25–35% smaller than JPG at equal quality, and it supports transparency, so it covers both of the jobs PNG and JPG split between them. Supported by every current browser.
- AVIF
- Smaller again than WebP, and the best compression available here. Slower to encode, which is noticeable on a large batch, and support in older software is thinner.
- BMP
- Uncompressed and universally readable. Files are very large — an uncompressed pixel grid — so this is for compatibility with old or embedded software rather than for storage.
- ICO
- The Windows icon and favicon format, able to hold several sizes in one file so the browser or system can choose the appropriate one.
- Quality
- Applies to JPG, WebP and AVIF, defaulting to 85%. That is visually indistinguishable from the source for almost any photograph. PNG and BMP ignore it, being lossless.
Choosing a format
| Format | Lossless | Transparency | Best for |
|---|---|---|---|
| PNG | Yes | Yes | Screenshots, logos, diagrams |
| JPG | No | No | Photographs, maximum compatibility |
| WebP | No | Yes | The web — smaller than both |
| AVIF | No | Yes | Smallest files, slower to make |
| BMP | Yes | No | Legacy and embedded software |
| ICO | Yes | Yes | Favicons and Windows icons |
Limits and what to expect
- 50 files per batch, 100 MB per file and 300 MB per queue.
- Converting between lossy formats adds a second generation of loss, whatever the quality setting.
- AVIF encoding is noticeably slower than the others, which compounds across a batch.
- Animated GIFs lose their animation — only the first frame is converted.
- Images beyond roughly 100 megapixels are refused, because an oversized browser canvas renders blank.
Troubleshooting
- My transparent background became a solid colour
- You converted to JPG or BMP, neither of which can store an alpha channel. Transparent pixels are filled with the background colour before encoding. Choose PNG, WebP or AVIF to keep transparency.
- The converted file is larger than the original
- You probably converted a photograph to PNG or BMP. Both are lossless, so they store photographic detail in full — often several times the size of the JPG. For photographs, choose JPG, WebP or AVIF.
- The image looks worse after converting
- Converting from one lossy format to another means decoding an already-degraded image and discarding more. Raise the quality towards 95%, or convert from a lossless original if you have one.
- AVIF is taking a long time
- AVIF encoding is computationally heavier than the others, and it runs on your device. For a large batch where the last few percent of size matters less than the wait, WebP gets most of the benefit far more quickly.
Your files and your privacy
Decoding and re-encoding both happen on a canvas inside your browser tab, using your own device. No image is uploaded, and batches are zipped locally too, so even a 50-file queue never leaves your machine.
What to use next
FAQ
Which image format should I use?
WebP for anything going on the web — it is smaller than JPG and supports transparency like PNG, and every current browser reads it. PNG for screenshots, logos and diagrams where you need lossless pixels. JPG when maximum compatibility matters more than size.
Will converting reduce my image quality?
Converting to a lossless format — PNG or BMP — loses nothing. Converting to JPG, WebP or AVIF discards data by design. If the source was already lossy, you get a second generation of loss regardless of the quality setting.
What happens to transparency?
PNG, WebP, AVIF and ICO keep it. JPG and BMP cannot store it at all, so transparent areas are filled with the background colour you choose before the image is encoded.
Is AVIF worth the extra time?
For a small number of images where size matters — a hero image on a page, say — yes, it beats WebP measurably. Across a large batch the encoding time adds up quickly and WebP captures most of the benefit for much less waiting.
Can I convert several images at once?
Yes, up to 50 files within 300 MB. They all use the same output format and quality, and the finished images download together as a single ZIP.
Are my images uploaded?
No. Everything happens on a canvas in your browser, on your own device, with no request to any server.