Image Converter

Choosing a format

Three formats with genuinely different design goals: JPEG discards detail the eye is least sensitive to and cannot get it back; PNG compresses losslessly and supports full alpha transparency; WebP offers both modes and is usually smaller than either at matched quality.

WebP

The best default for the web. It compresses noticeably smaller than JPEG at comparable quality, supports transparency like PNG, and is supported by every current browser. Converting a page's images to WebP is usually the single largest saving available.

JPEG

Still the right answer for photographs headed somewhere with uncertain support — email attachments, older software, print submissions. It is lossy and has no transparency: any transparent area is filled with white here rather than turning black, which is what a naive conversion produces.

PNG

Lossless, with transparency. Correct for screenshots, logos, diagrams, and anything with sharp edges or text, where JPEG's compression leaves visible artefacts. The quality slider is disabled for PNG because lossless compression has no quality setting to trade against.

Quality and file size

For the lossy formats, quality controls how much detail is discarded. Around 80% is the usual sweet spot: the difference from the original is hard to see, while the file is often a fraction of the size. Below roughly 60% compression artefacts become visible, particularly around text and sharp edges.

Resizing usually saves more than quality does. An image displayed at 800 pixels wide gains nothing from being 4000 pixels wide, and the pixel count — not the compression setting — dominates the file size. Setting a maximum width is the first thing to try. Images already smaller than the bounds are left alone rather than being enlarged, since upscaling adds bytes without adding detail.

Common uses

• Preparing images for a website.Resize to the largest size actually displayed and convert to WebP.
• Getting under an upload limit.Forms that reject anything over a couple of megabytes are common; lower the quality or the dimensions until it fits.
• Converting a screenshot for sharing.PNG screenshots are large; JPEG or WebP shrinks them dramatically when the exact pixels do not matter.
• Fixing orientation.Rotate photographs that came off a phone or camera sideways.
• Cropping out sensitive detail.Remove a region from a screenshot before sharing it.

Format support and limits

• Readingworks for any format your browser can decode, which includes PNG, JPEG, WebP, GIF, BMP, and usually AVIF.
• Writingis limited to PNG, JPEG, and WebP. Browsers can decode AVIF but cannot encode it, so it is not offered as an output format.
• HEIC— the default on iPhones — cannot be decoded by any browser without an external library. Convert those on the device first.
• Animated GIFslose their animation: only the first frame is converted, because the canvas holds a single frame.
• SVGis a vector format. It rasterises at its declared size, and any external references it makes will not resolve.

Things that trip people up

• Converting PNG to JPEG loses transparency.There is no alpha channel in JPEG. Transparent areas are filled with white here; keep PNG or WebP if transparency matters.
• Quality is not recoverable.Re-saving a JPEG at higher quality does not restore detail already discarded. Always convert from the best original you have.
• The output can be larger than the input.Converting an already-compressed JPEG to PNG will usually increase the size considerably, since PNG cannot discard anything. The percentage beside each result shows this.
• Metadata is not preserved.EXIF data — camera settings, timestamps, and GPS coordinates — is dropped during conversion. That is a privacy benefit more often than a loss, but it does mean location data will not survive.
• Very large images are memory hungry.A 50-megapixel photograph occupies around 200 MB once decoded, regardless of its file size on disk. Converting many at once can exhaust a tab's memory.