What is this calculator?
Re-encodes a JPEG image as PNG in your browser. PNG stores the decoded pixels losslessly, so nothing further is lost — but it cannot recover detail the original JPEG compression already discarded, and the file will usually be larger.
Use it when:
- A tool or workflow requires PNG input.
- You are about to edit the image and want no further compression loss between steps.
- You need an image format that survives repeated saving without degrading.
Intended for: Designers and developers who need a lossless working copy or a PNG-only input.
How is this calculated?
- The file you choose is read only for its type and name — nothing is uploaded, and the image itself never leaves your device.
- The tool validates that the source format is supported and that the requested output format and quality are valid together, producing a deterministic conversion plan: output format, quality, output file name, and the transparency and metadata policies that will apply.
- The output file name is derived from the source name with its extension replaced, so the result is predictable rather than randomly named.
- Your browser then decodes the image, draws it to a canvas at its original dimensions, and re-encodes it in the target format using its own built-in encoder.
- Because the image is decoded to raw pixels and re-encoded, the output carries only pixel data — embedded metadata such as EXIF is not preserved.
- PNG is a lossless format, so the quality setting does not apply and the decoded pixels are stored exactly.
Example
Converting `photo.jpg` to PNG.
- The JPEG is decoded to pixels; those pixels already carry whatever the original compression discarded.
- PNG stores them exactly, with no quality setting involved.
Result: `photo.png`, pixel-identical to the decoded JPEG and typically several times larger, since PNG does not compress photographic detail well.
Frequently asked questions
Does converting to PNG improve the image quality?
No. PNG preserves exactly what the JPEG decoded to, including its existing compression artefacts. Lost detail cannot be recovered by changing format.
Why is the PNG so much larger than the JPEG?
PNG is lossless and is designed for flat colour and sharp edges. Photographic images, which JPEG compresses very efficiently, are among the worst cases for PNG — several times larger is normal.
When is this conversion actually worth doing?
When a tool requires PNG, or when you will edit and re-save repeatedly — each JPEG save loses a little more, whereas PNG saves are lossless.
Is my image uploaded anywhere?
No. The image is decoded and re-encoded by your own browser. It is never transmitted to a server, and nothing is stored after you leave the page.
Assumptions
What this calculator takes as given:
- Conversion happens entirely in your browser; the image is never uploaded to or stored on a server.
- Pixel dimensions are preserved exactly — the tool changes the format, not the size.
- The quality setting applies only to lossy encoders (JPEG and WebP); PNG is always lossless.
- Encoding uses your browser's own image encoder, so the exact output bytes can differ slightly between browsers.
- PNG is lossless, so no quality setting applies to the output.
Limitations
What this calculator cannot know or does not model:
- Metadata such as EXIF, GPS coordinates, and colour profiles is not carried over — useful for privacy, but a loss if you needed it.
- Resizing, cropping, rotation, and other edits are outside the tool's scope.
- Animated images are converted as a single still frame.
- Very large images may exhaust browser memory, since decoding happens in the page.
- The final file size depends on your browser's encoder and cannot be predicted before encoding.
- Detail already lost to the original JPEG compression cannot be recovered.
- The PNG output is usually considerably larger than the JPEG input for photographic content.