Why PNG files get so big
PNG uses lossless compression, so it stores every pixel without discarding detail. Screenshots on macOS, Windows and phones, along with exports from design tools, usually save as .png by default. For a detailed photo or a full-screen capture, that easily produces a file several times larger than an equivalent JPG.
When you hit an email attachment limit, an upload cap, or a form that only accepts .jpg or .jpeg, converting the PNG to JPG solves the size and format problem.
What actually happens during conversion
PNG and JPG store images differently, so converting means decoding the PNG into raw pixels and encoding those pixels again as a JPG. Every current browser already has a PNG decoder built in, so the file is read with the browser's own file API and decoded right inside this tab with no extra download and nothing uploaded anywhere.
Quality, transparency, and when to keep the PNG
Quality and file size: The quality slider lets you trade file size for visual detail before you download. Lowering quality shrinks the file further; raising it preserves more detail. Because a PNG is lossless, this conversion to JPG is the step where detail gets dropped. Saving that JPG back to PNG later will only make a larger file and will not restore detail that was already compressed away.
Transparent backgrounds: JPG has no alpha channel and cannot store transparency. Any fully transparent or semi-transparent pixels in your PNG are filled in with solid white during conversion.
When PNG is the better format to keep: JPG is built for photographs and gradients. For screenshots with small text, UI icons, logos and flat graphics, PNG stays sharper, while JPG compression can soften edges and introduce visible artifacts around letters. If you do not need a smaller file or a strict .jpg upload, keeping the original PNG is often the better choice.
What this tool doesn't do
It converts a single picture. If you drop in an animated PNG (APNG), only the first frame is exported as a still JPG, and the remaining frames are not included.
A side effect worth knowing about: no metadata comes along
PNG files can carry text chunks (such as creator software, comments or export details) and, sometimes, full EXIF blocks, including from phone screenshots and photo exports.
Converting through this tool decodes the PNG down to raw pixels and writes those pixels out fresh as a JPG. That process never reads or carries forward separate metadata blocks, so the download has none. It is simply a side effect of how pixel-level conversion works, not a separate cleaning step. If you want to inspect what an existing JPEG or PNG is carrying and strip metadata without re-encoding, our free EXIF remover does that in the same browser tab.
A smaller file that uploads where you need it is the whole job. This tool gets you there without sending your image to anyone's server. That is not what Vaultine does. Vaultine is where you lock private files away, not where you convert them, though both come from the same idea: your files should stay on your terms.
