Converting PNG to JPG or WebP: which format to use and why
You upload a logo with a transparent background to a site that only accepts JPG, and the transparent area turns solid black or white for no obvious reason. Or a designer sends you a file with a .webp extension, and it throws an error on your machine because the old viewer installed there has never heard of that format. Both cases come from the same root cause: every image format is built for a different purpose, and mixing them up is what causes these surprises.
The practical difference between common formats
PNG keeps every detail of an image with no loss, and supports transparency — which is why it's used for logos and graphics with a see-through background. JPG, by contrast, compresses the image with a small, usually unnoticeable loss of detail, but doesn't support transparency at all; any transparent part of a PNG turns into a solid background color once converted to JPG. WebP and AVIF are the newer pair, combining transparency with a much smaller file size than PNG at roughly the same quality, though some older programs and sites still don't support them.
The image format converter on Sahel converts directly between PNG, JPG, WebP and AVIF, with a quality slider for lossy formats like JPG and WebP, and it can convert several images at once instead of one at a time.
What if the image is HEIC from an iPhone?
iPhone photos save by default as HEIC, a format many websites and older Windows machines simply won't open. That case comes up often enough to deserve its own dedicated tool: HEIC to JPG handles that specific format with settings tuned for it, while the general converter here focuses on switching between PNG, JPG, WebP and AVIF.
Steps to convert
- Upload the image or images you want to convert.
- Choose the output format: JPG, PNG, WebP or AVIF.
- Set the quality level if the format supports compression, balancing size against sharpness.
- Start the conversion and wait a few seconds depending on the number and size of images.
- Download the converted files and check the background renders correctly if the source image had transparency.
A common mistake: transparency vanishes without warning
The most common surprise people run into is converting a logo with a transparent background to JPG and watching a solid white or black background appear in its place with no warning. That's not a bug in the tool — it's a basic property of JPG itself, which has no concept of transparency to begin with. The fix is converting to PNG or WebP instead of JPG whenever transparency matters, and reserving JPG for images with a full background already, like ordinary photographs.
A subtler mistake is converting an already-compressed image (a low-quality JPG, say) to PNG hoping to sharpen it back up. Conversion can't recover detail already lost in the first round of compression — it just copies what's there into a larger file with no real gain in clarity.
A real case
An online store owner receives product photos from the manufacturer as high-quality, fairly large PNG files, and the storefront platform they use throttles page load speed when images are heavy — even though the products don't need transparency at all, since they're already shot on a plain white background.
They batch-convert the images to high-quality WebP through the tool, and file sizes drop noticeably with no visible difference in how sharp the products look. The store's pages load faster, and the shopping experience improves with no other edit to the images themselves besides changing their format.
Frequently asked
Does an image lose quality when converted to JPG?
It depends on the quality level chosen; a high setting (90% or above) gives a difference invisible to the naked eye, while a lower setting shrinks the file further but loses fine detail that can show up when zoomed in.
What's the size difference between WebP and JPG?
WebP usually produces a smaller file than JPG at roughly the same quality level, which is why many modern websites rely on it to speed up page loads.
Can several images be converted at once?
Yes, several images can be uploaded together and all converted to the same chosen format in one pass, instead of repeating the steps for each image separately.
Do images stay on the server after conversion?
No, uploaded images are deleted automatically once the converted version is handed back, and no account is required to use the tool.
Which format is best for website images?
WebP is a solid default for most cases thanks to its small size at acceptable quality, but JPG remains the most compatible with every browser and older platform if compatibility matters more than size.
Try the tool
Open the image format converter, upload your images, pick the format that fits your use, and download the result ready in seconds.