JPEG vs PNG vs WebP — Which Image Format Should You Use?

May 17, 2026  ·  7 min read

Pick the wrong image format and you'll either waste bandwidth with enormous files or end up with blurry logos and artefact-riddled photos. Pick the right one and your images load fast, look sharp, and work everywhere.

The choice comes down to three formats: JPEG, PNG, and WebP. Each has real strengths and real weaknesses. Here's exactly when to use each one.

The Three Formats at a Glance

JPEG — The Universal Standard

How JPEG Compression Works (Lossy)

JPEG uses lossy compression — it permanently discards some image data to achieve a smaller file size. The algorithm works by dividing the image into 8x8 pixel blocks, applying a mathematical transform (DCT — Discrete Cosine Transform), and then quantising the result, discarding high-frequency detail that the human eye is less sensitive to.

At high quality settings (85–100%), this data loss is essentially invisible to the human eye. At low quality settings (below 60%), you start to see JPEG artefacts: blocky squares, colour bleeding, and smearing around high-contrast edges. Every time you re-save a JPEG, the quality loss compounds — so avoid re-saving JPEGs repeatedly.

When to Use JPEG

JPEG is the right choice for:

• Photographs: Complex, natural images with millions of colours benefit most from JPEG compression. Landscapes, portraits, product shots — JPEG handles these well
• Email attachments: JPEG is universally supported by every email client
• Legacy compatibility: Any environment where WebP isn't supported (older CMS, some email clients, older software)
• Social media uploads: Most platforms recompress images anyway, so starting with JPEG is fine

A good rule: if you're looking at a photo and it doesn't contain text or a transparent area, JPEG is probably the right format.

When NOT to Use JPEG

Avoid JPEG for:

• Logos: JPEG compression smears the clean edges of logos and text, making them look blurry or blocky
• Images with text: The compression artefacts appear most visibly around high-contrast text edges
• Transparency: JPEG has no alpha channel. If you need a transparent background, use PNG or WebP
• Screenshots: Screenshots of UI have sharp edges that JPEG compresses poorly — PNG or WebP will look much better
• Source files: Never save your master/working copy as JPEG — use PNG or a lossless format

PNG — Lossless and Transparent

How PNG Compression Works (Lossless)

PNG uses lossless compression — it reduces file size without discarding any image data. The algorithm (DEFLATE) identifies patterns and repetition in the pixel data and encodes them efficiently, but every pixel in the original is preserved perfectly. Open a PNG, save it again, open it again — it's bit-for-bit identical each time.

This is why PNG files tend to be larger than JPEG. For a photograph with millions of unique colour values and minimal repetition, PNG can't compress effectively — the file size can be 3–10x larger than an equivalent JPEG.

When to Use PNG

• Logos and icons: Clean edges, flat colours, and text all compress very well in PNG and look sharp at any size
• Transparent images: PNG supports full 8-bit alpha transparency. If you need a transparent background, PNG is the standard
• Screenshots: UI screenshots have lots of colour uniformity and sharp edges — PNG handles these perfectly
• Diagrams and charts: Flat colours and text compress well and look crisp in PNG
• Source files for editing: PNG is the right format to save working copies — no quality loss on re-save

When NOT to Use PNG

The main case where PNG fails: photographs. A PNG of a full-colour photo can easily be 3–8MB. The same photo as a JPEG at 85% quality might be 200–400KB. For web pages and mobile, that difference in load time is enormous.

If you're looking at a photo and thinking of saving it as PNG "for better quality" — don't. Use compress images online to get a well-optimised JPEG or WebP instead.

You can always convert JPG to PNG when you specifically need transparency or lossless quality — but for photos destined for the web, PNG is overkill.

WebP — The Modern Choice

How WebP Achieves Smaller File Sizes

WebP was developed by Google and released in 2010. It uses a more advanced compression algorithm than either JPEG or PNG, drawing from video compression research (specifically the VP8 codec for lossy, and a derivative of PNG for lossless).

For lossy compression, WebP is typically 25–35% smaller than JPEG at equivalent visual quality. For lossless compression, WebP is typically 25–34% smaller than PNG. It also supports animation (like GIF, but with far better quality and compression), transparency in both lossy and lossless modes, and HDR.

Browser Support — Now 97%+ Globally

The main historical knock against WebP was browser support — older browsers didn't support it. That's no longer a real concern. As of 2025, WebP is supported by all major browsers: Chrome, Firefox, Safari (since Safari 14), Edge, and Opera. Global browser support sits above 97%.

The only environments where WebP may not display: Internet Explorer (essentially dead), some very old Android WebViews, and a handful of legacy software tools. For any modern public-facing website, WebP support is essentially universal.

When to Use WebP

WebP is the right choice for almost everything on the web:

• Website photos: Smaller than JPEG with equivalent or better quality
• Web graphics and logos with transparency: Smaller than PNG, supports alpha
• Blog post images: Faster page loads, better Core Web Vitals scores
• E-commerce product images: Same quality at a fraction of the bandwidth
• Anything where load speed matters: WebP is the best single format for web performance

You can compress WebP files further if needed, or compress JPEG files — both tools run in your browser with no upload required, so your files stay on your device.

Side-by-Side Comparison

Which Format Should You Choose?

Here's a simple decision flow:

• Is it going on a website? → Use WebP. It's the best performing format for all web use cases
• Do you need transparency? → WebP (preferred) or PNG if WebP isn't an option
• Is it a logo, icon, or text-heavy graphic? → WebP (lossless) or PNG
• Is it a photograph going via email? → JPEG (universal compatibility)
• Is it a source file you'll edit later? → PNG (lossless, re-editable)
• Is it going to a social media platform? → JPEG or PNG — the platform will recompress anyway
• Does it need to open in very old software? → JPEG or PNG (100% compatibility)

When in doubt for web use: WebP. When in doubt for anything else: JPEG for photos, PNG for graphics.

How to Convert Between Formats — Free

You can convert between JPEG, PNG, and WebP for free using JustDownsize's conversion tools. Everything runs in your browser — your files never leave your device, nothing is uploaded to a server. This is important when dealing with images that contain personal information, client assets, or proprietary content.

The most common conversions:

• Convert JPG to PNG — when you need transparency or lossless quality
• Compress JPEG files — reduce file size while maintaining visual quality
• Compress WebP files — optimise WebP output for web use
• Compress images online — smart compression for any format

Frequently Asked Questions

Which image format is best for websites?

For most websites, WebP is the best choice — it produces smaller files than both JPEG and PNG at equivalent quality, supports transparency, and is now supported by over 97% of browsers. Use WebP for both photos and graphics. Fall back to JPEG for photos and PNG for graphics only if you need to support very old browsers.

When should I use PNG instead of JPEG?

Use PNG when you need a transparent background, when your image contains text or sharp lines that JPEG compression would blur, or when you need a lossless copy for further editing. PNG is ideal for logos, icons, screenshots, and diagrams. Avoid PNG for photographs — file sizes can be 3–8x larger than JPEG or WebP at the same visual quality.

Is WebP better than JPEG?

Yes, in most ways. WebP is typically 25–35% smaller than JPEG at the same visual quality, supports transparency and lossless mode, and browser support now exceeds 97% globally. The main reason to use JPEG is compatibility with older software or email clients that don't support WebP yet.

Can I convert JPEG to PNG or WebP for free?

Yes. JustDownsize lets you convert between image formats for free, entirely in your browser — no upload required. Your files never leave your device. You can convert JPEG to PNG, PNG to WebP, WebP to JPEG, and more. The conversion happens instantly using browser-based processing.