The Free Image Converter Guide: PNG, JPG, WebP, SVG, BMP and PDF Explained
A portal wants JPG and you have PNG. A designer sent WebP and your software refuses to open it. A form insists on a PDF of a picture. Every one of those is a job for an image converter, and every one is quicker than it sounds. This guide explains what actually happens when you convert image files from one format to another, which formats go in and out of the free online image converter above, what the quality slider trades, and why transparency and metadata behave the way they do.
1. A Conversion Is a Re-Encode, Not a Rename
The most common mistake with image formats is changing the three letters at the end of the filename and expecting the file to change with them. It does not. A PNG called photo.jpg is still a PNG inside; the extension is a label, the format is the bytes underneath, and any checker that reads the bytes sees through the label. That is the whole story behind renamed png to jpg still not working.
A real photo format converter decodes the picture from its genuine bytes into a grid of pixels, then writes that grid out again under the rules of the format you chose: the ISO/IEC 10918 JPEG standard for JPG, the W3C PNG specification for PNG. Because the content is read rather than the name, a mislabelled PNG comes out as a genuine JPEG that a strict form will accept. Three consequences follow:
- Only the pixels survive. Camera metadata, GPS tags and colour profiles do not (section 5).
- The destination format sets the rules. JPG has no transparency, so transparent areas must become something. PNG is lossless, so it gets no quality slider.
- Only the first frame of an animation is read. For animated GIFs, use the GIF compressor or GIF maker instead.
2. How to Convert an Image Online Free (Step-by-Step)
The steps are the same whether you want to know how to convert WebP to JPG, convert PNG to JPG for a form, or convert JPG to WebP for a website. No account, no email step, no watermark.
Drop in one image
Choose a PNG, JPG, WebP, GIF, BMP or SVG in the panel above. It is recognised as an image and the outputs are listed. One file per run.
Pick the output format
PNG, JPG, WebP or PDF, pre-set to a format different from the one you started with. JPG and WebP reveal a quality slider; PNG and PDF have nothing to set. A GIF button is also listed, but it does not write a true GIF file, so skip it (section 3).
Convert and download
Press convert. A result card shows the new file, named after the original with the new extension, its size in kilobytes and a download link.
If a JPG or WebP came out larger than you hoped, lower the slider and convert again; the original stays selected. If the job is size rather than format, the image compressor keeps the format you have.
3. Formats In, Formats Out: PNG, JPG, WebP, BMP, SVG and PDF
Six inputs are recognised and four outputs are worth choosing; anything else is covered in section 7. A fifth button labelled GIF appears in the output list, but it does not produce a genuine GIF — the file it writes is not GIF-encoded and only carries the .gif name — so do not use it for anything that must open as a GIF. To make or shrink a real GIF, use the GIF maker or GIF compressor.
Accepted inputs
PNG, JPG/JPEG, WebP, GIF (first frame only), BMP and SVG, recognised from the filename extension.
Written outputs
PNG (lossless, keeps transparency), JPG (small, no transparency, quality slider), WebP (small, keeps transparency, quality slider) and PDF (one page, sized to the picture).
The conversions people run most
- WebP to JPG or PNG. The fix when a webp image won’t open. Pick PNG for transparency or sharp edges, JPG for photographs. The WebP to PNG tool does only that, if you prefer.
- Convert SVG to PNG. A vector logo becomes a fixed-pixel picture at the size the SVG declares. There is no scale control; if the result is too small, run it through the image enlarger. For vector-to-vector work use the vector converter.
- Convert BMP to PNG. An old Paint bitmap becomes a much smaller file with nothing lost; both formats store every pixel exactly.
4. The JPG Quality Slider: What Percentage to Use
Choose JPG or WebP and a single slider appears, from 40% to 100% in steps of five, set to 90% by default. The number is not a percentage of file size; it is how much detail the encoder may discard. Lower values throw away the subtle variation the eye notices least, which is why files shrink while the picture still looks like the picture — up to a point. So, to jpg quality slider what percentage to use:
- 90% (the default) when unsure: hard to tell from the original, noticeably smaller.
- 75–85% for web images and email attachments. Photographs look fine; small text starts to show faint blockiness.
- 95–100% when the picture will be edited again. Size climbs steeply for little visible gain.
The slider does not aim at a target file size. If a portal says “under 200 KB”, step down until the result card fits, or hand the JPG to the JPEG compressor; PNGs go to the PNG compressor.
5. Transparency, Black Backgrounds and EXIF Metadata
Why PNG to JPG turns the transparent background black
JPG has no concept of transparency. Every pixel must be a colour, so when a transparent PNG is written as a JPG the see-through areas have to become something, and the JPEG encoder settles them as black. That is the complaint behind png to jpg transparent background turns black, and the direct answer is that this tool has no option to fill transparency with white first; for a white-backed JPG, flatten the graphic onto white in an editor, then convert. The cleaner answer is usually not to use JPG: if the destination accepts PNG or WebP, choose one and the transparency comes through untouched. The same goes for convert WebP to PNG keep transparency; WebP alpha is carried straight into the PNG with nothing to set.
Metadata does not survive the conversion
A camera or phone photo carries hidden data alongside the pixels: make and model, exposure, date, often GPS coordinates. Because the new file is written from the pixels alone, none of it is carried across. If you wanted to remove EXIF data when converting image files, there is no extra step: the output has no EXIF block, no GPS tag and no embedded colour profile. Photographers who need that data should keep the original. A related side effect: a phone photo stored sideways with an orientation flag is written the right way up.
6. Convert Image to PDF at the Exact Size of the Image
Choosing PDF creates a single page whose dimensions are exactly the pixel dimensions of your picture. A wide screenshot gives a landscape page, a tall phone photo a portrait one, decided automatically, and the image fills the page edge to edge: no A4 fitting, no margin, no white border. That is precisely what convert image to pdf same size as image asks for. For a printable sheet, run the result through the PDF page resizer afterwards and pick A4 or Letter.
It is one picture to one page. To convert image to PDF in bulk, the image panel on the PDF to JPG tool takes any number of images at once, or convert each here and combine them with the PDF merger.
7. “Invalid File Format”, “Unsupported Image Format” and the HEIC Problem
When an upload form says invalid file format for an image, or an app throws an unsupported image format error, it is one of three things.
- The format is not on the list. The form wants JPG or PNG and you have WebP, BMP or SVG. Convert to one it accepts and the error disappears.
- The extension lies. Someone renamed the file and the checker read the real bytes. Converting writes a genuine file in the chosen format.
- The file is HEIC or HEIF. The usual cause with photos straight off a recent iPhone, and the one this converter cannot help with: HEIC is not a recognised input, so the conversion fails.
For HEIC the fix lives in the phone: sharing a photo usually offers a “most compatible” option, and the camera can be set to capture JPG. The same honesty goes for TIFF, AVIF, ICO, PSD and camera RAW: none is read here and none is written. Nor is this the tool for animations; build one from a clip with MP4 to GIF.
8. Why Cortexis Is the Best Free Image Converter
Image converter, no signup
No account, no email, no trial that ends. Drop in a picture and convert it, every time.
Image converter without watermark
Nothing is stamped on the output. The JPG, PNG, WebP or PDF you download is only your picture.
A private image converter
Your files are never stored on our servers, nothing is retained after your session, and nothing is used for training or analytics. ID scans are safe here.
No file size cap
A full-resolution photograph or large scan is accepted as readily as a small icon. No paid tier holds a bigger limit back.
A real quality control
A 40–100% slider in steps of five, not a Low/Medium/High dropdown, with the resulting size shown before you download.
Pixel-exact PDF pages
Image to PDF makes a page the exact size of the picture, no margins, orientation chosen for you.
It sits alongside a wider set of free image and document tools on the same terms, and for audio, video and spreadsheets the same panel works as a universal file converter.
9. Frequently Asked Questions (FAQ)
What is the best free image converter with no signup and no watermark?
The one at the top of this page: no account, no email, no stamp on the output. It reads PNG, JPG, WebP, GIF, BMP and SVG, writes PNG, JPG, WebP or PDF one picture at a time, and your files are never stored on our servers.
How do I convert WebP to JPG?
Choose the WebP file in the panel above, select JPG, leave the quality slider at 90% unless you need a smaller file, and press convert. If the WebP has transparent areas, choose PNG instead so they are preserved rather than filled with black.
I renamed a PNG to .jpg and the upload form still rejects it. Why?
Renaming changes the label, not the file. The form reads the actual bytes, sees a PNG and refuses it. Convert with JPG as the output and the file is genuinely re-encoded as a JPEG, which the form will accept.
Why does my transparent PNG have a black background after converting to JPG?
JPG cannot store transparency, so transparent pixels must become a colour, and the JPEG encoder makes them black. This tool has no fill-colour option. Convert to PNG or WebP to keep the transparency, or place the graphic on a white layer in an editor first.
Does converting PNG to JPG remove metadata?
Yes. The output is written from the pixels alone, so camera details, dates, GPS coordinates and colour profiles are not carried across in any direction. A privacy advantage when sharing, and a reason to keep the original.
Can I convert HEIC photos from my iPhone here?
No. HEIC is not among the formats this converter reads, so the conversion fails. Share the photo from the phone using its most-compatible option, or set the camera to capture JPG, then convert the result here.
Need the picture changed as well as converted? The image resizer sets exact dimensions, the JPEG compressor gets a photo under a portal’s size limit, and PDF to PNG, WebP, TIFF and BMP runs the other way. To understand why formats behave as they do, our free graphic design course covers raster and vector, compression and colour from the beginning.