If you have ever tried to email a handful of photos and watched the attachment size climb past the limit, there is a good chance those photos were saved as PNG. PNG is a wonderful format, but it was never designed for photographs. Converting a PNG photo to JPEG is one of the simplest ways to make an image smaller without anyone noticing a difference.
This guide explains why the two formats behave so differently, what you gain and what you give up when you switch, and how to get a clean result with the PNG to JPEG converter.
Why PNG photos are so large
PNG uses lossless compression. Every single pixel is stored exactly as it was, and the file is squeezed by finding repeated patterns. That works brilliantly for images with large flat areas of colour, such as screenshots, diagrams, icons and logos. A screenshot of a document might be mostly white, so PNG can describe it very efficiently.
A photograph is different. Every pixel is slightly different from its neighbour because of light, texture, shadows and camera noise. There are very few repeated patterns to exploit, so a lossless format ends up storing almost everything. It is common for a phone photo saved as PNG to be three to five times larger than the same photo saved as JPEG.
What JPEG does differently
JPEG uses lossy compression. Instead of storing every pixel exactly, it stores a very close approximation, and it throws away detail that human eyes are bad at noticing. Our eyes are much more sensitive to changes in brightness than to small changes in colour, so JPEG keeps brightness detail and simplifies colour detail.
The result is a file that looks almost identical at normal viewing size but takes a fraction of the space. The trade-off is that the approximation is permanent. Once an image has been saved as JPEG, the discarded detail is gone. That is why it is a good idea to keep your original PNG if you might need to edit it later.
The one thing JPEG cannot do: transparency
PNG supports transparency. A logo can have a see-through background so it sits neatly on any colour. JPEG has no transparency at all. Every pixel must have a solid colour.
So what happens to the transparent parts when you convert? They have to be filled with something. Our converter detects transparency in your file before you convert, tells you about it, and lets you choose the background colour. White is the default, because most documents and web pages are white, but you can pick any colour. If your logo will sit on a dark blue banner, choose that blue and the edges will blend naturally.
If you need the transparent background to stay transparent, JPEG is the wrong target. Consider PNG to WebP instead, which keeps transparency and still produces small files.
Choosing a quality setting
The quality slider runs from 1 to 100. Higher numbers keep more detail and produce larger files. A few practical rules:
- 85 (the default) is a sweet spot for most photos. You will struggle to see any difference from the original on a normal screen.
- 90 to 95 is worth it for images you plan to print or crop heavily.
- 70 to 80 is fine for thumbnails, previews or images you are sending over a slow connection.
- Below 60 you will usually start to see blocky patches in smooth areas such as skies, and fuzzy halos around sharp edges.
There is rarely a reason to use 100. It produces a much bigger file without a visible improvement, because JPEG is still lossy even at its highest setting.
Step by step
- Open the PNG to JPEG tool.
- Choose your PNG file, or drag it onto the upload area. The page checks the file type and size before anything is sent, so you will know straight away if it is not a real PNG.
- If your image has transparent areas, pick a background colour. You will see a notice explaining what will happen.
- Adjust the quality if you want to. The default is a sensible choice for almost everyone.
- Press Convert to JPEG and wait a moment. Most images finish in a few seconds.
- Press Download to save your new file.
The result page tells you the size of the new file and lists any changes the converter made, so nothing happens silently.
What stays the same, and what does not
The converter keeps your image at the same width and height. It does not resize or crop anything. If your PNG contains a colour profile, which some professional editing tools embed, that profile is carried over so colours look the same.
Some things are deliberately left behind. Hidden metadata, such as the camera model or the location where a photo was taken, is not copied into the new file. Most people never notice this, but it is a small privacy bonus when you share images online.
Very large images are supported, but there are sensible limits on dimensions and file size to keep the service fast for everyone. The exact limits are shown on the tool page before you upload.
When not to convert
JPEG is not always the right answer. Avoid it for:
- Screenshots with lots of text. JPEG can leave faint smudges around sharp letters. PNG or WebP will look crisper and are often smaller for this kind of image anyway.
- Logos and icons that need transparency.
- Images you will keep editing. Every time you open, edit and save a JPEG, a little more detail is lost. Keep a PNG master and export JPEG copies when you need them.
- Line drawings and diagrams with flat colours, where PNG is already efficient.
A quick real-world example
Imagine a 4,000 by 3,000 pixel holiday photo saved as PNG at around 18 MB. Converted to JPEG at quality 85, the same photo is often between 3 and 5 MB, and side by side on a laptop screen most people cannot tell which is which. That difference is the gap between an email that bounces and one that arrives.
Your files stay private
Files you upload are used only to create your conversion. They are stored privately, every download uses a short-lived link, and both the original and the result are deleted automatically after a short retention period. If you convert as a guest, your download is removed even sooner, shortly after you save it.
In short
Convert PNG to JPEG when you have photographs that need to be smaller for email, websites or messaging apps. Keep the default quality unless you have a reason to change it, choose a sensible background colour if your image has transparent areas, and hold on to your original PNG if you might edit it again. When in doubt, try a conversion and compare the two files: the size difference is usually obvious, and the visual difference usually is not.