Online Image Converter - Convert Between JPEG, PNG, WebP, and More with StackConvert
Rahmat UllahEvery image format makes a tradeoff. JPEG keeps files small but loses data. PNG keeps everything but files are huge. WebP is great for the web but not every tool supports it. Here is how to pick the right one and switch between them.
Table of Contents
Introduction
You would think image formats would be straightforward, but they are weirdly complicated once you actually need to pick one. Someone sends you a TIFF and you need a JPEG for a website. Your logo is a JPEG with a white background and you need it on a transparent PNG. You have a folder of PNGs that are 5MB each and need to get them down to something reasonable for email.
You do not need Photoshop for any of this. StackConvert's image converter handles format switching in your browser - JPEG, PNG, WebP, TIFF, BMP, AVIF, GIF, and a few others. The file never leaves your device because all the processing happens client-side in JavaScript.
Why Format Matters: Quality vs. File Size
Choosing the right image format is a tradeoff between visual quality and file size. Here is how the main formats compare:
| Factor | JPEG | PNG | WebP |
|---|---|---|---|
| Compression | Lossy | Lossless | Both lossy and lossless |
| File Size | Small | Large | Smallest |
| Transparency | No | Yes | Yes |
| Best For | Photos | Graphics, logos, screenshots | Web images (photos and graphics) |
| Browser Support | Universal | Universal | All modern browsers |
The key tradeoff: lossy compression (JPEG) discards some image data permanently to achieve smaller files. Lossless compression (PNG) keeps every pixel intact but produces larger files. WebP offers the best of both worlds but is not supported by every application.
Image Formats Compared: JPEG, PNG, WebP, GIF, and More
| Format | Best For | Compression | Limitations |
|---|---|---|---|
| JPEG | Photographs, complex scenes | Lossy | No transparency, quality degrades with re-saving |
| PNG | Logos, icons, screenshots, graphics with transparency | Lossless | Large file size for photos |
| WebP | All web images | Both lossy and lossless | Not supported by all image editors and older software |
| GIF | Simple animations, small graphics | Lossless (limited palette) | Only 256 colors, large animation files |
| TIFF | Print, publishing, archival | Lossless | Very large files, not web-friendly |
| BMP | Legacy systems | Uncompressed | Extremely large files |
| AVIF | Next-gen web images | Both lossy and lossless | Limited software and browser support |
Understanding these differences helps you pick the right format for each situation. For example, converting a PNG screenshot to JPEG before emailing it can cut the file size dramatically, while converting a JPEG logo to PNG preserves sharp edges and adds transparency support.
What Is Wrong with Most Image Converters
The same problems that plague file converters in general apply to image converters specifically. Most of them upload your image to their server, do the conversion there, and send you back the result. Your photo of a client's product, your company's unreleased logo, your personal pictures - all sitting on someone else's infrastructure. Some services claim they delete files after an hour, but you have no way to verify that.
Then there is the quality problem. Some converters apply aggressive compression during the conversion, so even a format change that should be lossless ends up producing a noticeably worse image. Others cap how many conversions you can do per day, or lock certain output formats behind a paid tier. For something that your browser can do locally in milliseconds, requiring a subscription feels absurd.
How StackConvert Handles It
StackConvert's image converter runs entirely in your browser. Your image loads into the browser's memory, JavaScript re-encodes it in the target format, and you download the result. No server is involved, so your images never leave your device.
There is no account to create, no daily limit on how many images you can convert, and no formats locked behind a paywall. The output quality matches what you would get from desktop software - you control the format and settings, and the converter does not apply any extra compression beyond what you choose. It works on any modern browser, desktop or mobile.
How to Convert
Open the image converter, drag in your image or click to select it, choose the output format from the dropdown, and hit convert. The browser processes it locally and gives you a download. Takes a few seconds for most images, even large ones.
When Should You Convert an Image?
| Situation | Recommended Conversion | Why |
|---|---|---|
| Website images loading slowly | PNG/JPEG to WebP | WebP produces smaller files for the web |
| Logo needs a transparent background | JPEG to PNG | PNG supports transparency, JPEG does not |
| Photo too large to email | PNG/BMP to JPEG | JPEG compression makes photos much smaller |
| Client requires a specific format | Any to requested format | Different platforms and clients have different requirements |
| Archiving high-quality images | JPEG to PNG or TIFF | Lossless formats prevent further quality loss |
| Social media uploads | TIFF/BMP to JPEG or PNG | Social platforms accept JPEG and PNG, not TIFF or BMP |
Other Image Tools
Beyond format conversion, StackConvert has a few other image tools that come in handy. The Base64 encoder/decoder is useful for embedding images directly in HTML or CSS. The metadata extractor lets you check EXIF data, dimensions, and camera settings. The aspect ratio finder calculates the ratio of any image, which is helpful when resizing for different platforms. And images to PDF combines multiple images into a single document. All of them run client-side, same as the converter.
Common Questions
What is an online image converter?
It is a browser-based tool that changes an image from one format to another, such as JPEG to PNG or PNG to WebP.
Are my images uploaded to a server?
No. StackConvert processes images entirely in your browser. Your files never leave your device.
Do I need to create an account?
No. You can start converting images immediately without signing up.
Will converting an image reduce its quality?
It depends on the format. Converting to a lossy format like JPEG involves some quality reduction to achieve smaller files. Converting to a lossless format like PNG preserves full quality. The conversion itself does not add any extra degradation beyond what the target format requires.
What is the difference between lossy and lossless?
Lossy compression (JPEG, lossy WebP) discards some image data to make files smaller. You cannot get that data back. Lossless compression (PNG, lossless WebP) reduces file size without losing any image data.
Wrapping Up
There is no single best image format - it depends on what you are doing with the image. Use JPEG for photos where file size matters, PNG when you need transparency or lossless quality, and WebP when you are optimizing for the web. Most people end up needing to switch between them more often than they expect.
When you do, StackConvert's image converter handles it in your browser. No uploads, no accounts, and the output is the same quality you would get from desktop software.