Convert Images Online

Why Convert Images Between Formats?

Image conversion isn't just a technical exercise—it solves real problems you encounter every day.

Compatibility Issues

The most common reason for conversion is simple: your file won't open. Apple's HEIC format is a perfect example. Since 2017, iPhones have saved photos as HEIC by default because it offers better quality at smaller file sizes than JPEG. The problem? Many Windows applications, older software, and websites still don't support it.

When you try to upload an HEIC photo to a website form, attach it to an email for a Windows user, or open it in older photo editing software, you're stuck. Converting to JPEG solves the problem instantly—JPEG is supported virtually everywhere.

Web Performance

If you run a website, image format directly affects your loading speed. A photograph saved as PNG might be 5MB. The same image as JPEG could be 500KB. As WebP, it might shrink to 350KB. And as AVIF, perhaps 250KB.

That's a 20x difference between the worst and best choice. For a page with 10 images, you could be forcing visitors to download 50MB instead of 2.5MB. On mobile connections, that's the difference between a page that loads in 2 seconds versus one that takes 30 seconds.

Transparency Needs

Sometimes you need to add or remove transparency. A logo with a white background looks terrible on a colored website header. You need PNG or WebP format to maintain a transparent background. Conversely, if you're printing photos, transparency isn't supported—you need solid backgrounds that JPEG provides.

Storage and Archiving

Professional photographers often shoot in RAW format for maximum quality, then convert to JPEG or PNG for sharing. Graphic designers work in layered formats like PSD, then export to PNG or WebP for web use. The working format and the delivery format serve different purposes.

Understanding Image Formats

Each format exists for a reason. Understanding their strengths and weaknesses helps you make better conversion decisions.

JPEG: The Universal Standard

JPEG has been around since 1992 and remains the most widely supported image format in existence. Every device, every browser, every application can open a JPEG file. This universality is its greatest strength.

JPEG uses lossy compression, which means it permanently discards some image data to achieve smaller files. For photographs, this tradeoff works well—the human eye doesn't notice the subtle details that get removed. A well-compressed JPEG can be 10-20 times smaller than an uncompressed image while looking virtually identical.

However, JPEG struggles with graphics, text, and sharp edges. It also doesn't support transparency. If you see fuzzy halos around text or logos in a JPEG, that's the compression algorithm struggling with high-contrast edges.

PNG: Lossless and Transparent

PNG was created in 1996 as a patent-free alternative to GIF. Its key advantages are lossless compression (no quality loss, ever) and full alpha transparency (256 levels of opacity, not just on/off).

For graphics, logos, screenshots, and anything with text or sharp edges, PNG delivers pixel-perfect quality. The transparency support makes it essential for web design—logos, icons, and UI elements need to work on any background color.

The downside is file size. PNG photographs are enormous because the lossless compression can't exploit the redundancies that make photos compressible. A photo that's 500KB as JPEG might be 5MB as PNG—with no visible quality improvement.

WebP: The Modern Web Standard

Google introduced WebP in 2010 to solve a simple problem: web images were too large. WebP offers both lossy and lossless compression, supports transparency, and even handles animation—all in files 25-35% smaller than equivalent JPEGs or PNGs.

How does it achieve this? WebP uses more sophisticated compression algorithms, including techniques borrowed from video codecs. It analyzes images more thoroughly and encodes them more efficiently than older formats could.

With 97%+ browser support in 2024, WebP has become the practical choice for most web images. The only real limitation is that some older software and systems don't support it.

AVIF: Maximum Compression

AVIF is the newest mainstream format, based on the AV1 video codec. It pushes compression even further than WebP—typically producing files 30-50% smaller at equivalent quality.

The tradeoff is encoding speed. Creating an AVIF file takes significantly longer than JPEG or WebP. For one-off conversions this doesn't matter, but for batch processing thousands of images, the time adds up.

Browser support has grown quickly, reaching about 93% in 2024. For websites prioritizing performance, AVIF represents the current state of the art.

HEIC/HEIF: Apple's Choice

HEIC (High Efficiency Image Container) is based on the HEVC video codec and has been the default format for iPhone photos since iOS 11 in 2017. It offers roughly 50% smaller file sizes than JPEG at the same quality—significant when you're storing thousands of photos on a phone.

The challenge is compatibility. While Apple devices handle HEIC natively, Windows requires additional codecs, many websites reject HEIC uploads, and older software doesn't recognize the format at all. Converting to JPEG or PNG remains necessary for sharing with non-Apple users.

What Happens During Conversion

When you convert an image, the software decodes the original format into raw pixel data, then re-encodes it in the new format. This seemingly simple process has important implications.

Lossy to Lossy: Quality Loss Accumulates

Converting from one lossy format to another (like JPEG to WebP) means the image is compressed twice. Each compression pass can introduce artifacts. While modern encoders minimize this, there's no way to recover quality that was already lost.

This is why professionals always keep original, uncompressed source files. You can generate as many JPEG or WebP versions as you need from a lossless master, but you can't reconstruct the master from a compressed copy.

Lossless to Lossy: One-Way Trip

Converting PNG to JPEG reduces file size dramatically but discards the mathematical perfection of lossless compression. The JPEG will look good, but it's no longer bit-for-bit identical to the original.

More importantly, transparency is lost. Any transparent areas become solid—typically white, though some converters let you choose the background color.

Lossy to Lossless: No Quality Gain

A common misconception is that converting JPEG to PNG somehow improves quality. It doesn't. The PNG version perfectly preserves the JPEG's pixels—including all its compression artifacts. You get a larger file that looks exactly the same.

The only reason to do this is if you need to edit the image further without additional quality loss, or if you need the PNG format for compatibility with specific software.

Choosing the Right Output Format

With so many options, how do you decide? Here's a practical decision framework.

For Maximum Compatibility

When you need the image to work everywhere—email attachments, document embedding, older software, any device—choose JPEG for photos or PNG for graphics. These formats have been universal standards for decades and will open anywhere.

For Web Performance

For website images in 2024, WebP is usually the best choice. It offers significant size savings over JPEG and PNG while working in all modern browsers. If you need maximum compression and can accept slightly longer encoding times, AVIF pushes the boundaries even further.

For Quality Preservation

When quality matters more than file size—archiving important photos, preparing images for printing, preserving graphics for future editing—use PNG. Its lossless compression ensures no quality degradation, ever.

For Transparency

If your image needs a transparent background, your options are PNG, WebP, or AVIF. Choose PNG for maximum compatibility, WebP for web use with good compression, or AVIF for cutting-edge compression where browser support permits.

Understanding Quality Settings

When converting to lossy formats (JPEG, lossy WebP, AVIF), you'll encounter a quality slider. Understanding what it does helps you make better choices.

The Quality-Size Tradeoff

Quality settings typically range from 1-100, where higher numbers mean better quality but larger files. But the relationship isn't linear.

From quality 100 to 90, you lose almost nothing visible while cutting file size significantly. From 90 to 80, you save more space with minimal visual impact. From 80 to 70, trained eyes might spot differences in detailed areas. Below 60, artifacts become obvious to most viewers.

Finding the Sweet Spot

For most photographs, quality 80-85 offers an excellent balance. You'll save 60-80% of the file size compared to quality 100, with differences that are essentially invisible at normal viewing distances.

For web images that will be viewed at small sizes, you can often go lower—quality 70 or even 60 may be perfectly acceptable for thumbnails.

How This Converter Works

This tool brings format conversion directly to your browser, with some important advantages over traditional online converters.

Browser-Based Processing

Unlike services that upload your files to remote servers, we process everything locally using WebAssembly technology. Your images are decoded and re-encoded right in your browser tab. Nothing is transmitted over the internet.

This approach means your files stay completely private. It also means conversion starts instantly—there's no upload wait time, no server queue, no download step at the end.

Supported Conversions

We support a wide range of input formats and convert them to the most useful output options:

Batch Processing

You can convert up to 20 images at once. Drop them all in, select your output format, and convert them together. Each file is processed independently, so a problem with one image won't affect the others.