JPG vs PNG vs WebP: which format to use

QuickConvert’s compress, convert, and resize tools read and write JPG, PNG, and WebP. They do not open HEIC, GIF, AVIF, BMP, or PDF. That limit is the practical boundary of the canvas encoders those pages use. If a phone handed you a HEIC, convert it with HEIC to JPG, then use Image Convert or Image Compress on the JPG. The comparison below is only about the three formats those tools handle, because advice about a format you cannot produce there is not useful in this article.

All three can hold a photo. They do not hold it the same way, and they do not all hold transparency.

JPG (the file is often named .jpg, and the type is image/jpeg) was built for photographs. It throws away detail your eye tends not to miss, and that is why a camera picture becomes a manageable file. It has no alpha channel. A transparent pixel cannot stay transparent. On this site, converting or compressing to JPG fills those pixels with white before encoding, so a logo on a clear background becomes a logo on a white box. The white is deliberate. A JPEG decoder has to put some color there, and white is predictable.

Use JPG when the picture is a photo, the recipient is a person rather than a website you control, and transparency does not matter. Email, office documents, and older tools accept JPG almost everywhere. The quality slider on Image Convert starts at 90, and on Image Compress at 80. Those are encoding qualities, not a grade of the camera. 90 keeps a photo close to the pixels you decoded. Dropping toward the bottom of the slider, which starts at 10, will show blocks, especially around text and faces. You cannot undo that from the saved JPG. Keep the file you started with.

Saving a JPG again and again at a lower quality stacks the loss. Convert or compress from the original, not from last week’s already-compressed export, when you have the choice.

PNG is lossless. The quality slider does nothing for it, and the tools disable the slider when PNG is the output. That is why a PNG screenshot often refuses to shrink until you change format or reduce the pixel size. A quality number cannot discard PNG information that the format insists on keeping.

Use PNG for logos, diagrams, interface screenshots, and any graphic with a transparent background you need to keep. Also use it when another program demands PNG and you are willing to accept a larger file. Do not convert a photo from JPG to PNG to “improve” it. The conversion wraps the same pixels in a heavier container. Detail the JPEG already discarded does not come back.

PNG is the right intermediate when you are still editing and you do not want another lossy save. It is often the wrong attachment when the photo is a holiday picture and the mailbox is complaining about size.

WebP can store a lossy photo in less space than a JPG at a similar looking quality, and it can also store transparency. For a site you control, it is often the format to publish. For a file you are handing to someone else, test that their tools open it. Some older office apps and some mail previews still stumble on WebP, which is why JPG remains the safer “send to a person” choice.

On this site, WebP uses the same quality slider as JPG. Image Compress can write WebP from a PNG or a JPG. Image Convert can switch among the three without changing width and height. A transparent PNG converted to WebP keeps the canvas alpha; converted to JPG, it is painted on white.

WebP will not rescue a tiny icon that is already a few kilobytes, and it will not make a huge PNG screenshot small if you also need every pixel to stay crisp and you refuse to shrink the dimensions. Pair the format with a size cap when the pixel dimensions are the real weight. Image Compress can cap the long edge at the same time as it encodes. The default cap is 1920 pixels on the longer side.

• Photo you will email or drop in a document: JPG at a high quality, long edge around 1920 if the original is a camera file.
• Photo on a website you control: WebP, with a JPG fallback only if you have measured that you need one.
• Logo, diagram, or screenshot with sharp UI and possible transparency: PNG, or WebP if you have checked transparency in the destination.
• PNG that is accidentally a photo and far too big: Smart compress, which saves PNG as JPG and leaves an existing JPG or WebP in its own format, or an explicit WebP if you know it will open.

Image Resize can change pixels and format together. Image Convert changes format only, which is what you want when the dimensions are already right and a second resample would only soften the picture.

None of these tools upload the image. They decode it in the browser, draw it, and download the result. The format decision is still yours, and it is worth making on a copy. The longer privacy notes are in privacy with online file tools.