Every picture on the web lives in a container, and that container decides how big the file is, whether it can be transparent, and how much detail survives saving. A photograph saved as a BMP can be dozens of times larger than the same photograph saved as a JPEG, while a logo with sharp edges and transparency can look terrible as a JPEG even though the file is small. Converting between formats is therefore not just a technical chore; it is a decision about quality, size and compatibility. The Image Format Converter handles that conversion in your browser, so you can change a picture from one supported format to another without installing software or sending the image to a server.
The reason so many formats exist is that they solve different problems. JPEG was designed for photographs. It throws away some detail the human eye barely notices, which is why a photo can shrink dramatically with little visible change. PNG was designed for graphics where every pixel matters: it compresses without losing any data, and it supports transparency, which makes it the usual choice for logos, icons and screenshots. WebP is a newer format that tries to give you the best of both, with lossy compression for photos and lossless compression plus transparency for graphics. BMP, PPM and PGM are much simpler formats. BMP stores pixels almost exactly as they appear, with a small header in front, which makes it easy for other programs to read but usually large. PPM and PGM are plain, simple formats from the portable pixmap family: PPM stores colour images and PGM stores greyscale images, and both are popular in teaching and in simple image-processing pipelines because their structure is so easy to understand.
How the tool works
The converter works entirely in your browser. You provide an image, choose the format you want, and download the result. Because the work happens on your own device, the picture never travels to a remote server, which matters if you are working with private screenshots or unreleased designs. The tool offers six outputs: PNG, JPEG, WebP, BMP, PPM and PGM. That list is deliberate. Those are the formats the tool can genuinely produce, and the page says plainly which formats it does not produce: PSD, SVG, TIFF, TGA and HEIC are not offered as outputs, and HEIC input is not supported either. That honesty matters, because a converter that silently pretends to support a format it cannot handle will waste far more of your time than one that tells you the limit up front.
Conversion itself is not magic. When you convert a JPEG photograph to PNG, the file usually gets bigger, because PNG keeps every pixel exactly and cannot use the shortcuts JPEG used. That does not mean the picture gets better; detail that JPEG already discarded cannot be recovered by converting to a lossless format. The reverse trip is where quality decisions bite: converting a PNG logo to JPEG will fill transparent areas with a solid colour and can blur sharp edges, because JPEG was never designed for flat colours and hard boundaries. The safest habit is to keep your original file, convert a copy, and compare the two before you replace anything.
A worked example
Take a tiny test pattern four pixels wide and two pixels tall, built from simple colours. Converted to BMP, that image is 78 bytes: a 54-byte header plus two rows of pixel data, each row 12 bytes, with no padding needed because the row size already lines up. A two-pixel-wide, one-pixel-tall BMP comes out at 62 bytes by the same arithmetic: the same 54-byte header plus one 8-byte row. These numbers are worth knowing because they show exactly how BMP works. There is no clever compression hiding in the file; the size is the header plus the raw pixels, row by row. The same test pattern converted to PNG would be smaller, because PNG compresses the pixel data, and converted to JPEG it would be smaller still, because JPEG discards some detail. If you ever doubt what a converter did, checking the output size against this kind of simple arithmetic is a fast reality check.
A more everyday example helps too. Suppose you have a product photograph that is currently a PNG of several megabytes, and you need it for a web page. Converting it to JPEG or WebP will usually cut the size sharply with no visible difference at normal viewing sizes, because photographs contain exactly the kind of smooth colour variation those formats compress well. Suppose instead you have a logo with a transparent background, currently a JPEG with an ugly white box behind it. Converting that JPEG to PNG will not restore the transparency, because the JPEG never stored it. You need the original logo file, or a version that was saved with transparency in the first place. Format conversion changes the container; it cannot invent information the original file never held.
Common mistakes
The most common mistake is converting in the wrong direction and expecting a quality gain. Going from a lossy format to a lossless one never restores lost detail, and it usually just makes a bigger file. A second mistake is choosing JPEG for anything with text, line art or transparency. JPEG smears sharp edges and replaces transparency with a solid background, so screenshots, diagrams and logos almost always look better as PNG or WebP. A third mistake is assuming that a smaller file is always better. For a photograph on a web page, smaller is usually good, but for an image you plan to edit further, a lossy format is a poor working format, because every save discards a little more detail. Keep a lossless master, and make lossy copies only for final delivery.
Another mistake is ignoring compatibility. WebP is well supported in modern browsers, but older tools and some desktop software may still struggle with it, so if you are handing a file to someone else, PNG or JPEG remains the safer choice. Similarly, BMP, PPM and PGM are simple and widely readable by image software, but they are poor choices for sharing online because of their size. Match the format to the destination: web pages favour JPEG, PNG and WebP; simple processing pipelines favour PPM and PGM; and archival or editing work favours a lossless format.
Honest limitations
This converter is a format changer, not an image editor. It does not resize, crop, rotate or retouch pictures, and it does not improve a blurry or low-resolution image. It cannot produce PSD, SVG, TIFF, TGA or HEIC files, and it cannot read HEIC input, so if your photo arrives in one of those formats you will need a different tool first. It also cannot recover detail lost by earlier lossy compression, and converting a file twice through lossy formats will lose quality twice. Those limits are not flaws to work around; they are the reason to keep your originals and to choose the target format deliberately.
Closing
Converting an image format is a small task, but it sits at the junction of quality, size and compatibility, and getting it wrong costs either bandwidth or visible quality. Convert a copy, pick the format that fits the destination, and check the result before you publish it. If you also need to shrink images for the web, the Image Optimizer and PDF to JPG cover neighbouring jobs, and How to Optimize Images for Websites explains the wider picture of size, quality and page speed.