Convert JPG to PNG without promising lost detail back

Re-encode one JPG, JPEG, or JFIF as PNG at the same pixel dimensions. The output avoids another lossy save, but it cannot reverse JPEG artifacts or invent transparency.

Published and updated September 14, 2026 · 6 minute read

Implementation details you can verify

The converter accepts one file identified as JPG, JPEG, or JFIF. The per-file limit is 50 MiB. After decoding, neither dimension may exceed 16,384 pixels and total width multiplied by height may not exceed 40,000,000 pixels. These decoded limits matter even when the compressed JPG is small.

The browser draws the decoded source onto a canvas with the same width and height and encodes that canvas as PNG. Source metadata is not explicitly copied. The tested example below documents one conversion and does not generalize its file-size result.

What lossless PNG encoding means here

PNG encoding is lossless relative to the decoded canvas: saving that canvas as PNG does not apply a new JPEG-style lossy compression pass. The original JPEG has already discarded or approximated information, however. Existing blocks, ringing, color changes, and softened edges become pixels in the PNG and remain visible.

Conversion also cannot recover an alpha channel. JPG-family files do not provide transparent pixels for this process to restore. The resulting PNG can support transparency as a format, but this conversion does not create transparent regions.

Suitable and unsuitable cases

Use this conversion when software requires PNG, when a stable lossless representation of the currently decoded pixels is useful, or before adding graphics in an editor that should avoid another lossy export. It can also suit screenshots that arrived as JPG, while preserving their existing artifacts.

It is unsuitable as a JPEG repair, quality enhancer, background remover, transparency generator, image resizer, or reliable file-size reducer. PNGs made from photographs are often larger than their JPG sources. Keep the original camera or master file if future editing or archival provenance matters.

Metadata, color, and privacy caveats

Source metadata is not explicitly copied, so EXIF orientation, camera data, location, dates, copyright fields, embedded thumbnails, and color-profile data should not be assumed to survive. Confirm orientation, color, and any required metadata in the downloaded PNG.

Decoding and PNG creation happen in the browser; the selected image is not posted to the document-conversion API. The page still loads third-party page assets, including hosted resources, so it is not equivalent to an offline application. Review the Privacy Policy before processing sensitive images.

Troubleshooting

The PNG is larger than the JPG

This is expected for many photographs. PNG preserves the decoded pixels losslessly, while JPG uses lossy compression optimized for continuous-tone imagery.

The PNG still has JPEG blocks

The blocks were already present in the decoded source. Re-encoding stops an additional lossy JPEG save but does not reconstruct discarded information.

A modest file is rejected as too large

Check dimensions, not only bytes. Reduce the image below 16,384 pixels on each side and no more than 40,000,000 total decoded pixels.

JPG-to-PNG FAQ

Are JFIF files supported?

Yes. The input accepts JPG, JPEG, and JFIF.

Will the PNG become transparent?

No. Conversion does not identify or remove a background.

Does the tool enlarge the image?

No. The decoded width and height remain unchanged.

Is PNG always better quality?

The new encoding is lossless relative to the decoded canvas, but source JPEG loss is already permanent.

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