PNG to JPG Converter
- Writing the JPG discards picture detail to save space, and what it discards does not come back.
- Transparent areas are laid onto #FFFFFF, because JPG carries no alpha channel here.
- The Exif data, the colour profile and anything else the original carried are not passed on: the picture is decoded to plain pixels and a new file is written from them.
- An animated PNG comes through as one picture — the image the format names as its default, or the first frame where it names none.
Needs JavaScript. Runs only here.
This page turns a PNG into a JPG on your own machine. Every conversion on this page runs in your browser. The picture is read, drawn and written on your own machine, and the file is not sent to a server.
Going the other way? Convert JPG back to PNG →
How do you convert a PNG to a JPG?
A PNG stores every pixel; a JPG stores an approximation of them in far fewer bytes. Two things change on the way: the clear areas get a colour, and detail goes.
A PNG converted to JPG becomes much smaller, and two things change for good: transparent areas are filled with a background colour, and JPEG compression discards detail. The quality setting decides how much.
- Choose the PNG file you want to convert. It is read inside this page, on your own machine.
- Pick the colour that goes behind the clear areas. This page starts at #FFFFFF and states the colour it used, because the browser's own default would fill them with black.
- Set the quality between 0 and 1. A lower setting writes a smaller file and throws more detail away, and no two browsers read the number the same way.
- Select Convert to JPG. The page reads the first bytes of what came back and refuses the file if they are not JPG.
- Download the JPG. Nothing has been sent anywhere, so the file is ready as soon as it is written.
What Changes From PNG to JPG
PNG to JPG makes the file much smaller and changes two things for good: the transparent areas are filled with a background colour, and JPEG compression discards detail according to the quality setting.
Each row below is one property of the picture: what it is in the PNG, what it becomes in the JPG, and whether it survives the trip. Convert a file and the same rows fill in with the measurements from your own picture.
| Property | In the PNG | In the JPG | Verdict |
|---|---|---|---|
| Dimensions | as the file has them | as the file has them | kept |
| Colour model and bit depth | RGB with alpha, 8 bits per channel | Y'CbCr, 8 bits per channel — 8 bits per sample, whatever the source held | changed |
| Alpha channel | present | flattened onto #FFFFFF | lost |
| Colours used | up to 16,777,216 | the same pixels | kept |
| Animation frames | 1, or several — PNG can carry an animation | 1 — the format’s default image, or the first frame where it names none | changed |
| Metadata (Exif, ICC) | present in the file | dropped — a new file is written from pixels | lost |
| Compression | lossless, deflate | lossy, discrete cosine transform (the baseline process) | changed |
| File size | the file you chose | smaller | changed |
the pixels survive; some of the detail, the transparency and the Exif data do not.
Going Back to PNG
Converting back does not restore what this step dropped, so convert the JPG result back to PNG only when you need a PNG file.
The change above runs one way — go back from JPG to PNG writes a new file, not the original.
What Travels With the Picture
What the two formats are, and what the browser does with a picture on the way between them. None of this depends on which PNG you bring.
How PNG and JPG Are Defined
| Property | PNG | JPG |
|---|---|---|
| Compression | lossless - deflate with a sliding window of at most 32768 bytes (compression method 0) | lossy, discrete cosine transform (the baseline sequential process); the standard also defines a separate lossless mode that web .jpg files do not use |
| Alpha channel | yes - a full alpha channel on colour types 4 and 6; a tRNS chunk gives a transparent colour key on types 0 and 2 and per-entry alpha on type 3 | none - neither T.81 nor JFIF defines an alpha or transparency channel |
| Animation | yes - APNG is normative in the Third Edition, using the acTL, fcTL and fdAT chunks | none - one image per file |
| In one sentence | PNG stores a picture without losing anything: the specification defines lossless as reconstructing the original data exactly, bit for bit. It carries an alpha channel, and since the Third Edition it can carry frame-based animation as well. | JPEG saves space by throwing detail away. The baseline process, which is what a .jpg file on the web uses, is lossy and cannot be undone, and the standard defines no transparency at all. |
- A PNG file begins 89 50 4E 47 0D 0A 1A 0A.
- A JPG file begins FF D8 (SOI); a JFIF file follows it with FF E0 and the identifier 4A 46 49 46 00.
- PNG is defined by PNG Specification (Third Edition), W3C Recommendation 24 June 2025; the Second Edition is ISO/IEC 15948:2004. The Third Edition is not itself an International Standard..
- JPEG is defined by ITU-T Rec. T.81 | ISO/IEC 10918-1 (JPEG); ITU-T Rec. T.871 | ISO/IEC 10918-5 (JFIF).
JPEG and lossy WebP save space by discarding picture detail, and what they discard does not come back. PNG, BMP and lossless WebP keep every pixel they are given, and GIF keeps every pixel it is left with after the palette has been applied.
PNG, GIF, WebP and ICO can carry transparency; JPEG cannot, because the standard defines no alpha channel, and a bitmap written here is opaque. Converting to a format without transparency fills the clear areas with a background colour.
Every save as JPEG compresses the picture again. A JPEG that has been converted and saved once more carries the loss from both steps, and the second one cannot be undone by going back.
Converting a picture back to the format it came from does not return the original file. Whatever a step discarded stays discarded, and the return trip writes a third file.
The browser decodes the picture to plain pixels and writes a new file from them, so the Exif data, the colour profile and anything else the original carried are not passed on.
A canvas holds pixels and nothing else, so a file written from one carries no Exif data, no thumbnail and none of the original file's other metadata. The canvas specification never mentions Exif; this follows from writing the file out of a bitmap.
When a canvas is written to a format that has no alpha channel, the browser lays the picture over opaque black. A converter that wants any other background has to paint it first, and should say which colour it used.
The quality setting applies only to formats that support variable quality, never to PNG, and it has to be a number between 0 and 1. Browsers read it differently, so the same setting does not give the same file everywhere.
What Does the Quality Setting Change?
What the setting actually controls
How much detail the encoder is allowed to throw away. A high setting keeps fine texture and writes a bigger file; a low one smooths it and writes a small one. The quality setting applies only to formats that support variable quality, never to PNG, and it has to be a number between 0 and 1. Browsers read it differently, so the same setting does not give the same file everywhere.
Where you will see it first
On sharp edges. Flat colour and gentle gradients survive a low setting well, while text, line art and a logo's outline pick up a halo of speckles long before a photograph looks wrong.
Why the choice is one-way
Raising the setting later cannot put back what a lower one removed, and each new save works on the previous result. Keep the PNG if you may need to write the JPG again at a different setting.
Common Mistakes
- Leaving the background to the browser. Its default fills the clear areas with black; this page starts at #FFFFFF and prints the colour it used.
- Saving the same picture as a JPG over and over. Every pass compresses it again.
- Using a JPG for a logo or a screenshot. Flat colour and sharp text are what JPEG compression handles worst.
Frequently Asked Questions
What's the difference between a PNG and a JPEG?
PNG stores a picture without losing anything: the specification defines lossless as reconstructing the original data exactly, bit for bit. It carries an alpha channel, and since the Third Edition it can carry frame-based animation as well.
What are the disadvantages of a PNG file?
Size, mostly. A PNG of a photograph is several times a JPEG of the same picture, because it keeps detail a photograph can spare. It also holds one frame here.
What does PNG stand for?
Portable Network Graphics. The name is on the specification the format is defined by, which the W3C published as a Recommendation in its Third Edition.
Can a PNG be converted to a JPG under 200 KB?
Often, by lowering the quality setting, but no setting guarantees a size: the answer depends on the picture. Convert, read the size on the result, and adjust.
What happens to a transparent background when a PNG becomes a JPG?
It is filled in with the colour you chose, and cannot be recovered from the JPG. When a canvas is written to a format that has no alpha channel, the browser lays the picture over opaque black. A converter that wants any other background has to paint it first, and should say which colour it used.
You can, but the round trip is not the file you started from: the JPG to PNG direction.
Related Conversions
The rest of the family sits on the rest of the image converters.