Convert PNG to JPEG

Key takeaways

• Photographs shrink a lot: 29.82 MB became 3.60 MB (-87.9%) at the converter's fixed quality of 0.92, with SSIM 0.991.
• Screenshots and text can get bigger: our 94.6 KB screenshot became 129 KB (+36.7%).
• Transparent areas turn white: 22.6% of the Apollo 11 insignia was fully transparent, and the JPEG shows it as white.
• The conversion is lossy and one way: the PNG's exact pixels are not kept, and converting the JPG back to PNG does not restore them.
• The quality is fixed at 0.92. For a file size limit, use the target size tool.

JPEG or JPG: is there a difference?

No. JPG and JPEG are two spellings of the same format. Older Windows versions limited extensions to three letters, which is where .jpg comes from. This page saves the file with the .jpg extension; rename it if a form insists on .jpeg.

Measured: PNG to JPG

Measured in headless Chromium with the converter's own steps: the image is drawn on a canvas, JPEG gets a white background, and the browser saves it at quality 0.92. SSIM compares the result with the browser's own decode of the input, flattened on white (1.0 would be identical). Test files: three public domain NASA scans (a 3840 × 3877 photo, a 2122 × 2644 portrait, a 3827 × 1588 handwritten document), the NASA Apollo 11 insignia as a 5380 × 5432 PNG with transparency, and a 1440 × 1000 screenshot of a page of this site. The PNG files for the photos were made losslessly from the JPEGs; the WebP files were made with libwebp at quality 85. Other browsers use their own encoders, so sizes can differ.

For the three photographic files the JPG was 85% to 91% smaller. The screenshot went the other way: 94.6 KB became 129 KB (+36.7%). PNG compresses flat color and sharp text very well, and JPEG does not.

What happens to transparent areas

JPG has no transparency, so the converter fills the background with white before saving. In the Apollo 11 insignia, 22.6% of the pixels were fully transparent and 0.1% partly transparent; all of them become white (or a blend with white). The JPG scored SSIM 0.958 against the insignia on a white background, lower than the photographs, because the sharp edge between shape and background is what JPEG handles worst.

If you need the transparency, keep the PNG, or convert to WebP, which keeps it.

PNG vs JPEG

What you get

A JPEG at 92% quality; transparent areas become white. JPEG and JPG are the same format; this is the same conversion as PNG to JPG.

When to keep the PNG

• Screenshots, text and line art: in our test the screenshot of text (png) was larger as a JPG and the JPG scored lower than the PNG's perfect reproduction.
• Anything with transparency: logos, stickers, cut-outs.
• Pictures you will edit again: every JPG save loses a little more.
• MDN's image guide says PNG is preferred over JPEG for more precise reproduction of source images, or when transparency is needed.

If the JPG is still too big

The converter saves at a fixed 0.92, which is a high setting. When a form or app has a limit, the target size tool searches the quality for you and shrinks the picture when quality alone is not enough. This is what it did with the 3.1 MB photograph (the one behind the first row, as a JPG):

The picture gets smaller as well as the file. For a fixed pixel size, resize first and then compress.

When the JPG is the right choice

• Photographs for email, messages, forms and uploads, where size matters more than exact pixels.
• A destination that does not take PNG. The photo case above saves 26.22 MB.
• Platforms re-encode what you upload anyway, so a high quality JPG loses little compared with a PNG.

Free tools:Compress an image with a sliderCompress an image to a target sizeCompress an image to 200 KBPNG to WebPJPG to PNG

Questions people ask

More converters

• PNG to JPG
• PNG to WebP
• JPG to JPEG
• WebP to JPEG
• HEIC to JPEG

Sources and how we checked

1. MDN: Media container formats
2. MDN: Web audio codec guide
3. MDN: Image file type and format guide
4. FFmpeg documentation: stream copy
5. MDN: Image file type and format guide (read 2026-10-09)
6. Wikimedia Commons: Buzz salutes the U.S. Flag (NASA, public domain), one of the photographs used (read 2026-10-09)

Reviewed October 8, 2026. What the converter writes was measured with ffprobe on the same FFmpeg build your browser downloads; format descriptions follow MDN's media guides.