Image Formats Explained: WebP vs PNG vs JPG - When to Use Each

Why image formats matter

Choosing the right image format isn’t just a technical detail. It directly impacts your website’s performance, user experience, and even search rankings. The wrong format can mean bloated file sizes, slow load times, and frustrated visitors. The right format delivers crisp images that load instantly.

In this guide, we’ll break down the most common image formats, explain when to use each one, and help you understand the key factors that affect file size and quality.

The big three: JPG, PNG, and WebP

JPG / JPEG. Best for photographs. Small file sizes, great for photos, and universal support. No transparency, and lossy only.

PNG. Best for graphics and logos. Supports transparency, lossless quality, and crisp edges. Larger file sizes, and overkill for photos.

WebP. Best of both worlds. The smallest file sizes, transparency support, lossy or lossless modes, animation support, and the modern standard.

Understanding lossy vs lossless compression

The fundamental difference between image formats comes down to how they compress data. Understanding this will help you make better decisions about which format to use.

Lossy compression

Lossy compression permanently removes some image data to achieve smaller file sizes. The “lost” data is typically information the human eye won’t notice, like subtle color variations or fine details in busy areas.

Formats: JPG, WebP (lossy mode).

Best for: Photographs, complex images with many colors, hero images, and backgrounds.

Lossless compression

Lossless compression reduces file size without losing any image data. The original image can be perfectly reconstructed. Think of it like a ZIP file for images.

Formats: PNG, WebP (lossless mode), GIF.

Best for: Logos, icons, graphics with text, screenshots, and images requiring transparency.

What affects image file size?

Three main factors determine how large your image files will be.

1. Dimensions (width by height)

The bigger the image dimensions, the more pixels need to be stored. A 4000 by 3000 image has 12 million pixels, which is 12 times more data than a 1000 by 1000 image (1 million pixels).

Pro tip. Never upload images larger than you need. If your website displays images at 800px wide, there’s no reason to upload 4000px originals. Resize first, then compress.

2. Quality level (compression ratio)

For lossy formats, the quality setting directly controls file size. Lower quality means smaller files, but more visible compression artifacts.

3. Image content and complexity

Images with lots of detail, colors, and gradients compress less efficiently than simple graphics. A photo of a forest will always be larger than a solid color logo at the same dimensions.

Complex photo. Larger file size.

Simple graphic. Smaller file size.

Deep dive: JPG (JPEG)

JPG (also called JPEG, they’re the same thing) has been the web’s workhorse image format since the 1990s. It uses lossy compression optimized for photographs and remains the most widely supported format.

When to use JPG

Great for: photographs and realistic images, hero images and backgrounds, product photos, social media images, and email attachments.

Avoid for: logos and icons, text-heavy graphics, images needing transparency, screenshots with UI elements, and images you’ll edit repeatedly.

The JPG artifact problem. Each time you save a JPG, it recompresses and loses more quality. This is called “generation loss.” If you open a JPG, make a small edit, and save it, you’ve just degraded the image. Always keep original files and only export to JPG as a final step.

Deep dive: PNG

PNG (Portable Network Graphics) was created as a patent-free alternative to GIF. It uses lossless compression and supports full transparency (alpha channel), making it perfect for graphics, logos, and images that need to overlay on different backgrounds.

When to use PNG

Great for: logos and brand assets, icons and UI elements, graphics with text, screenshots, images requiring transparency, and graphics with sharp edges.

Avoid for: large photographs, hero images, backgrounds with gradients, and situations where file size is critical.

PNG-8 vs PNG-24. PNG-8 uses a limited 256-color palette (like GIF) for smaller files. PNG-24 supports millions of colors and full transparency. Most modern usage is PNG-24, but PNG-8 can be useful for simple graphics where you want smaller files.

Deep dive: WebP

WebP is Google’s modern image format, designed specifically for the web. It combines the best features of both JPG and PNG: excellent compression for photos, transparency support, and even animation capabilities.

25-35%

Smaller than JPG at same quality

26%

Smaller than PNG (lossless)

97%

Browser support worldwide

When to use WebP

Great for: everything on the modern web, photographs (lossy mode), graphics and logos (lossless mode), transparent images, animated images (replacing GIF), and any time performance matters.

Consider alternatives for: email attachments (JPG is more compatible), print workflows, legacy system integration, and times when recipients need to edit the file.

Other formats you might encounter

GIF. Limited to 256 colors, supports animation and simple transparency. Largely replaced by WebP for animations and PNG for static images. Still used for simple animated memes due to universal support.

SVG. Vector format (not pixel-based) that scales infinitely without quality loss. Perfect for logos, icons, and illustrations. Not suitable for photographs. Small file sizes for simple graphics.

AVIF. Next-generation format with even better compression than WebP. Browser support is growing (around 93 percent) but not as universal yet. Consider for cutting-edge performance optimization.

HEIC/HEIF. Apple’s default photo format on iPhones. Excellent compression but limited web support. Convert to JPG or WebP for web use.

TIFF. High-quality lossless format used in print and professional photography. Huge file sizes, so never use for web. Convert to WebP or JPG.

BMP. Uncompressed bitmap format. Massive file sizes with no advantages. A legacy format, so always convert to something else.

Quick reference: which format should I use?

Convert your images with ScrapeConvert

Now that you understand the different formats, putting this knowledge into practice is easy. Our free ScrapeConvert converter lets you convert any image format to WebP, PNG, or JPG directly in your browser.

100 percent private. All conversion happens in your browser. Your images are never uploaded to any server.

Quality profiles. Choose from lossless, web optimized, social media, or maximum compression presets.

Batch processing. Convert multiple images at once. Drag and drop a folder of images and convert them all.

Powered by Squoosh. Uses Google’s Squoosh library for industry-leading compression quality.