format conversion

JPEG to PNG

This is the pair most likely to hand you a bigger file for no visible gain, and it is worth knowing why before you do it.

What actually changes

  • Lossless does not mean recovered

    The JPEG already decided which detail to throw away. PNG stores what it is given exactly — which here means storing an approximation exactly. Nothing comes back.

    Source The converter’s own format notes — src/copy/en/convert.ts

  • PNG settings matter more on this pair than on any other

    Measured here: PNG’s per-row adaptive filtering shrank a photograph by 25.8% and grew a flat vector mark by 5%. A JPEG source is usually a photograph, so it is the source kind that filtering actually helps.

    Source docs/v2/24 — PNG encoding, measured 2026-08-20

  • There is no transparency to carry over

    JPEG has no alpha channel, so the PNG arrives with an unused one. If you need a transparent background you will still have to cut it yourself; this conversion does not create one.

    Source The converter’s Output panel — src/copy/en/convert.ts

  • What you download is exactly what was compared

    Every source is decoded once into a lossless PNG master, and all three formats are encoded from that one picture. Resizing straight out of a JPEG lets each engine pick its own shrink-on-load factor, which would make the three sizes in the results table a comparison of three different pictures.

    Source src/lib/convert.worker.ts — the master decode, per docs/v2/22

The short answer

Do it when something needs a format that can carry an alpha channel you are about to add, or refuses JPEG outright. Not to improve the picture.

Convert it here

The converter takes your file, writes it as PNG, JPEG and WebP at the same pixel size, and shows you what each one weighs — measured on your file rather than on an average. It runs on the page using WebAssembly; the image never leaves your device.

Open the image converter

The other conversions

Every pair this tool can actually do. There are nine because it reads four formats and writes three, and a format cannot be converted to itself.

This page carries 4 facts and a source for each one. It is one of nine, generated from the same list the converter reads — so a page cannot exist here for a format the file picker would refuse.