How the conversion works
Each PNG is opened by your browser and drawn onto a canvas that has first been filled with your chosen color. Wherever the PNG is transparent, that color shows through; wherever it is partly transparent, the two are blended. The canvas is then saved as a JPG at the quality on the slider, with the same pixel dimensions and the same file name ending in .jpg.
diagram.png → paint fill color → draw the PNG on top → save as JPG at quality 92 → diagram.jpg
The whole process runs on your device. The PNGs are not uploaded, and nothing is kept once you close the page.
Choosing the fill color
This setting only matters for PNGs with transparency, but there it matters a lot. A logo with soft, anti-aliased edges is made of thousands of partly transparent pixels. Converted on white, those edges are blended toward white; if you later place that JPG on a navy background, you will see a pale fringe around every curve. Set the fill to the color the image will actually sit on, or keep transparent artwork as PNG.
When converting to JPG is a good idea
- Photos that were saved as PNG. Phone screenshots of photos, exports from editors and images from some cameras or scanners can be several megabytes as PNG. As JPG they shrink dramatically with no visible change.
- Upload limits. Forms that cap files at 1 or 2 MB, or that accept JPG only.
- Email and messaging. Smaller attachments send faster and fit inside mailbox limits.
When JPG is the wrong choice
JPG is built for photographs. It compresses by smoothing small blocks of the picture, which is invisible in a photo but shows up on hard edges as faint smudges and halos. Keep these as PNG:
- Screenshots with text. Letters pick up gray speckles around them, and small type can become hard to read.
- Logos and icons. Flat colors get blotchy and the transparency is lost.
- Charts, diagrams and line art. Thin lines blur and solid fills get noise.
- Anything you will keep editing. Every time a JPG is saved it loses a little more. Edit in PNG and convert once at the end.
Worked example: a scanned form for an upload portal
Your scanner saved a signed form as lease.png, 2550 × 3300 pixels and 9.8 MB, but the landlord's portal accepts only JPG under 2 MB. Drop it here, leave the fill on white (scans have no transparency, so it makes no difference), set quality to 85 and press Convert. The list shows the new size next to the old one. If it is still over 2 MB, drag the slider lower and press Convert again; the earlier result is discarded and replaced.
What else to know
Metadata in the PNG, such as text comments, DPI and color profile, is not copied into the JPG. Images over about 16.7 megapixels are scaled down to fit the browser's canvas limit, and the list says when that happened. If you drop a WebP, AVIF, GIF or BMP by mistake, it is converted to JPG the same way.
Questions people ask
What happens to the transparent parts of my PNG?
JPG has no transparency, so every see-through pixel is painted with the fill color you pick, white unless you change it. Partly transparent pixels, such as anti-aliased edges and drop shadows, are blended with that color, so choose the color of the page or slide the JPG will sit on and the edges will look clean.
Why did my logo come out with a white box around it?
That box is the fill color replacing the transparent background. If the logo will go on a dark or colored background, either set the fill to that color before converting, or keep the logo as PNG, which is the better format for logos anyway.
How much smaller will the JPG be?
For photos saved as PNG, the JPG is usually a fraction of the size, often a fifth or less at quality 92. For screenshots and flat graphics the saving is smaller, and very simple images can even come out larger as JPG. The list shows the exact before and after size for each file.
Which quality setting should I use?
92, the default, is visually identical to the PNG for photos. Lower it to 80 to 85 if you need smaller files for email or a size-limited upload form. Below about 70 you start to see blocky patches in smooth areas such as skies.
Are my PNG files uploaded?
No. Your browser opens each PNG and saves the JPG on your device. Nothing is sent to a server, which matters for screenshots that show account details, messages or other private information.
Can I convert many PNGs at once?
Yes, up to 200 per batch. Drop them all, set the quality and fill color once, and press Convert. Download each JPG on its own or all of them in one ZIP.