Convert PNG to JPG

Screenshots and photos are different jobs

Most PNGs on a Windows PC are screenshots: press Windows Print Screen and Windows saves a PNG in the Screenshots folder inside Pictures. Others are photos that an app or a website happened to save as PNG. The two behave very differently as JPG.

• Photos shrink a lot. JPG was made for smooth tones and fine texture, and a photo PNG often becomes a JPG a fraction of its size with no visible change.
• Screenshots full of text, menus and flat colors may barely shrink, and sometimes grow. PNG packs flat areas very tightly, and JPG tends to leave faint smudges around sharp letters.

There is a quick test: convert, then read the percentage next to the result. A minus sign means the JPG is smaller; a plus sign means the PNG was the leaner file all along.

So convert the photos, and think twice about screenshots. If a screenshot must be smaller, cutting it down to the part that matters usually does more than changing its format: the Photo Editor can crop it before you export.

Where the transparency goes

A PNG can have see-through parts: the space around a logo, a cut-out product, a rounded icon. JPG cannot, so every pixel needs a color. The Convert tool paints those parts white, which looks right on white pages, in documents and on most forms. Soft edges, like a shadow that fades out, are blended onto the white, so they look the way they did over a white page.

Two things to watch:

• On a dark or colored background, the JPG shows a white box around the shape. Keep the PNG for those uses, or make a smaller file that stays transparent with PNG to WebP.
• Need another color than white? Open the PNG in the Photo Editor and use Export: for JPG, See-through parts become takes any color.

Not sure whether a PNG has see-through parts? Look at the original in the Convert tool: transparent areas let a light checkerboard show through. In the JPG beside it, the same areas are plain white.

How small, at what quality

Quality in this tool runs from 10 to 100. Each time you move it, the JPG is made again and the result updates its file size and the percentage saved, so you can settle on a number by looking rather than guessing.

• 85 to 92 for photos you will share, print or keep.
• 70 to 80 for pictures shown small, such as thumbnails on a web page.
• Under 60 only when size is everything; blocks and halos appear around edges.

Need the picture smaller in pixels too? Open it in the Photo Editor and press Export instead: its Size list goes down to 512 pixels wide, and the W box takes any width, with Quality from 30 to 100. The compress JPEG page goes deeper into squeezing JPGs.

Other ways on Windows

Paint, which comes with Windows, can do a plain conversion too: open the PNG, then choose File, Save as, JPEG picture. It does not ask for a quality or show the file size before saving. Octoolo adds both, and leaves hidden details such as location out of the copy.

Online converters do the same job but need the picture uploaded first. That is worth avoiding for screenshots of email, banking, medical portals or anything from work, which is what many screenshots are. In Octoolo the PNG is read and the JPG is written on your own PC, and it works with no connection at all.

Whichever way you convert, keep the PNG if you might need it again: going back from JPG to PNG later does not restore what the JPG left out.