What the converter does to a file
All twelve converters share one engine, and it works the same way every time. Your browser decodes the image into a bitmap. It paints that bitmap onto an HTML canvas at exactly the original width and height. Then it asks the canvas to write a brand new file in the format you picked.
That last step has consequences.
A canvas stores colour values and nothing else. There is no slot in it for EXIF, IPTC or XMP. So the file that comes out the other side is rebuilt from pixels alone, and the camera model, the shutter speed, the capture date and the GPS coordinates baked into a phone photo do not make the journey. Rotation does survive, because the decoder is told to honour the EXIF orientation flag before anything is drawn, so a portrait shot stays portrait instead of flopping onto its side. Nothing is scaled either. A 4032 by 3024 iPhone photo comes out 4032 by 3024, and if you wanted it physically smaller rather than differently packaged, the image resizer is what you need.
Six formats in, three formats out
You can bring in PNG, JPG, WebP, GIF, BMP and AVIF. You can take away PNG, JPG or WebP.
That gap is deliberate. Browsers read far more image formats than they can write. The canvas toBlobmethod only has to produce PNG; every current browser throws in JPEG and WebP on top. None of them ship a canvas encoder for GIF, BMP or AVIF.
We could bolt on a separate encoder library for those. We would rather not list a conversion we cannot do properly, so the twelve pairs above are the twelve pairs that work.
Every format has a pixel ceiling, and WebP's is low
This one catches people converting scans, panoramas and long stitched screenshots. Nearly every converter page on the web leaves it out.
| Format | Maximum pixels per side | Where the limit comes from |
|---|---|---|
| PNG | 2,147,483,647 | 4-byte width and height in the IHDR chunk |
| JPG | 65,535 | 2-byte width and height in the SOF marker |
| GIF | 65,535 | 2-byte logical screen descriptor |
| WebP | 16,383 | 14-bit width and height in the VP8 bitstream |
Google's own WebP FAQ puts it plainly: the maximum pixel dimensions of a WebP image is 16383 x 16383.
Sixteen thousand pixels sounds like plenty. Then you stitch a set of A3 scans together, or export a big map tile, and you are suddenly 20,000 pixels wide. At that size no tool anywhere can save your image as WebP, because the format has nowhere to put the number. Use PNG instead. ThePNG spec gives width and height four bytes each, which is why it copes with almost anything you throw at it.
A second ceiling sits underneath all of this, and it belongs to the browser rather than the format. Canvases have size limits of their own. Chrome caps a canvas at 32,767 pixels a side and 268,435,456 pixels of area. Firefox allows 472,907,776 pixels of area. Safari on iOS sat at 4,096 by 4,096 for years and moved up to 8,192 by 8,192 in iOS 18. A huge conversion that runs fine on a desktop can therefore fail flat on a phone. If a big file errors on mobile, try it on a laptop before you decide the file is broken.
What else changes, besides the extension
Transparency goes white when the target is JPG. JPEG has no alpha channel at all. Before drawing, the converter fills the canvas with white, so transparent areas land on white rather than the black smear you get from tools that skip that step. Need the transparency? Convert to PNG or WebP.
Animated GIFs stop moving. A GIF fed into any of these comes out as its first frame and nothing else. The tool says so on screen when it happens. For a real animation you want theGIF maker rather than a format converter.
The quality slider does nothing for PNG. PNG is lossless, so there is no quality knob to turn, and the slider is hidden on those pages. It matters a lot for JPG and WebP. The default of 92 percent is a good place to start.
16-bit images come back as 8-bit. A standard 2D canvas holds eight bits per colour channel. Feed it a 16-bit PNG from a scanner and you get an ordinary 8-bit PNG back. Fine for photos. Not fine for archival or scientific work, where you want a proper desktop editor.
Choosing what to convert to
Pick JPG for photos going anywhere with a size limit, an upload form or a printer. Support is universal, files are small, and there is no transparency.
Pick PNG for screenshots, logos, diagrams, anything with sharp edges, and anything you want a lossless copy of. Files are usually bigger, sometimes a lot bigger.
Pick WebP for the web. It handles transparency and photo detail, and it typically lands 25 to 35 percent smaller than the JPG or PNG version. Browser support is universal now. Plenty of desktop programs and older devices still refuse to open it, though, so it is the wrong pick for a file you are emailing to a client.
One rule cuts across all three. Converting JPG to PNG does not restore quality. What JPEG threw away is gone, and a lossless wrapper just preserves the damage at a bigger file size.
Frequently asked questions
Which converter should I use?
Pick the one that matches your input and output, for example PNG to JPG. Each page only accepts its own source format and will tell you if you drop in the wrong thing.
Can I convert a whole folder at once?
Yes. Drag in as many files as you like, or paste them from the clipboard. Convert in one go, then download them one by one, or take the lot as a single ZIP once two or more have finished.
Why did my AVIF file fail to convert?
Your browser could not decode it. AVIF needs a recent Chrome or Edge, or a fairly current Safari. Older browsers, and corporate builds pinned to an old version, will just refuse the file. Try another browser.
Does converting to PNG make my photo look better?
No. PNG is lossless, which means it keeps exactly what you give it, artefacts and all. Lossless prevents new damage. It does not repair old damage.
Will the converted file be smaller?
That depends on the pair. JPG to WebP and PNG to WebP usually shrink a lot. JPG to PNG almost always grows, sometimes several times over, because you are moving lossy data into a lossless container. Each file shows its before and after size with the percentage change, so you can see what happened instead of guessing.
Do I lose the photo's date and location?
Yes, both. The converter rebuilds the file from pixel data, and metadata is not pixel data, so EXIF fields including GPS coordinates get dropped. Handy if you were about to post a holiday photo. Annoying if you sort albums by capture date. Keep the originals somewhere safe first.
Related: convert iPhone HEIC photos · shrink a file without changing format · change the pixel dimensions · strip metadata on its own