Image format conversion is one of the most common file tasks on the web — and one of the most frequently misunderstood. Choosing the wrong format doesn't just cost you file size. It can degrade image quality, break browser compatibility, or cause problems with printing, editing, and archiving.
This guide covers every major image format, when to use each, and exactly how to convert between them.
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The Major Image Formats Explained
JPEG / JPG
The most widely used format for photographs and complex images. JPEG uses lossy compression — it permanently discards visual data to reduce file size.
Use JPEG for:
- Photographs
- Images with gradients and many colours
- When file size matters more than perfect quality
- Email attachments and social media uploads
Avoid JPEG for:
- Screenshots with text (text becomes blurry)
- Images that need a transparent background
- Images you plan to edit and re-save repeatedly (every save loses more quality)
- Logos and icons
Quality setting: Most tools let you set JPEG quality 1–100. 80–85% is the sweet spot — virtually indistinguishable from 100% at roughly half the file size.
PNG (Portable Network Graphics)
PNG uses lossless compression — every pixel is preserved exactly. PNG also supports transparency (alpha channel), making it essential for logos, icons, and design assets.
Use PNG for:
- Logos, icons, and UI elements
- Screenshots with text or sharp edges
- Images that need transparent backgrounds
- Source files you'll edit and re-export
Avoid PNG for:
- Photographs (files will be 5–10× larger than equivalent JPEG with no visible quality gain)
- Large hero images on websites (use WebP instead)
WebP
Developed by Google, WebP provides superior compression compared to both JPEG and PNG, supporting both lossy and lossless modes plus transparency.
Use WebP for:
- Web images where performance matters
- Replacing JPEG photos on websites (25–35% smaller at the same quality)
- Replacing PNG graphics on websites (26% smaller on average)
Browser support: All modern browsers (Chrome, Firefox, Safari 14+, Edge). No longer a concern for most web projects.
Avoid WebP for:
- Email clients (many don't support it)
- Print workflows
- Legacy system requirements
AVIF
The newest entrant, based on the AV1 video codec. AVIF provides the best compression of any format — often 50% smaller than JPEG at equivalent quality.
Use AVIF for:
- Web images where maximum performance is the priority
- Hero images and large photography
- Replacing WebP where browser support allows
Browser support: Chrome 85+, Firefox 93+, Safari 16+. Still not universal — always provide a WebP or JPEG fallback with the <picture> element.
GIF
A legacy format supporting simple animation and limited colours (256 max). GIF is largely obsolete for static images — PNG is always better. For animation, WebP animation or short video files (MP4) are vastly more efficient.
Still used for: Animated reaction images and memes (cultural inertia, not technical merit).
SVG (Scalable Vector Graphics)
SVG is fundamentally different — it's a vector format that describes shapes mathematically rather than storing pixels. SVGs scale to any size perfectly with no quality loss.
Use SVG for:
- Logos and brand marks
- Icons
- Illustrations with solid shapes
- Any graphic that needs to look sharp at multiple sizes
Not suitable for: Photographs or complex images (SVG can't represent them efficiently).
Format Comparison at a Glance
| Format | Compression | Transparency | Animation | Best For |
|---|---|---|---|---|
| JPEG | Lossy | ❌ | ❌ | Photos |
| PNG | Lossless | ✅ | ❌ | Logos, screenshots |
| WebP | Both | ✅ | ✅ | Web images |
| AVIF | Both | ✅ | ✅ | Web (modern browsers) |
| GIF | Lossless | Limited | ✅ | Legacy animation |
| SVG | Vector | ✅ | ✅ | Icons, logos |
Common Conversion Scenarios
PNG → JPEG
When: You have a screenshot or design export as PNG and need to email it or upload it to a platform that prefers smaller files.
Watch out for: PNG→JPEG conversion removes transparency. Any transparent areas will become white (or whatever background colour the converter uses).
JPEG → PNG
When: You need to add a transparent background, or you're importing into a design tool that requires lossless files.
Note: Converting JPEG to PNG does not recover quality lost in the original JPEG compression. The resulting PNG will be lossless but still reflects the JPEG's compression artefacts.
Any format → WebP
When: Optimising images for a website. The single most impactful conversion for web performance.
PNG → SVG
Not a pixel-to-vector conversion — most tools trace the edges of a raster image to produce an approximate SVG. Results vary significantly. Works well for simple logos on solid backgrounds; not suitable for photographs.
Image Conversion and Web Performance
Google's Core Web Vitals (specifically Largest Contentful Paint — LCP) are directly affected by image size and format. Serving WebP or AVIF instead of JPEG typically improves LCP scores meaningfully.
Best practice for web: Serve multiple formats using the HTML <picture> element:
<picture>
<source srcset="image.avif" type="image/avif">
<source srcset="image.webp" type="image/webp">
<img src="image.jpg" alt="Description" loading="lazy">
</picture>
Browsers use the first format they support, falling back to JPEG for older browsers.
Privacy Note
FluxToolkit's image converter processes your images entirely within your browser using client-side JavaScript. Your image files are never uploaded to our servers. Conversion happens locally on your device — your images remain private.
Frequently Asked Questions
Does converting JPEG to PNG improve quality?
No. Converting JPEG to PNG produces a lossless PNG, but the quality reflects whatever JPEG compression was already applied. Pixel data lost in JPEG compression cannot be recovered by converting to another format.
What's the best format for website images?
WebP for broad compatibility; AVIF for maximum performance on modern browsers. Always provide a JPEG fallback. Use a <picture> element to serve the best format each browser supports.
Can I convert PNG to SVG?
Technically yes, but automated raster-to-vector conversion (tracing) works well only for simple images with clear edges and solid colours. Photographs cannot be meaningfully converted to SVG.
Why does my PNG have a white background after converting to JPEG?
JPEG doesn't support transparency. Any transparent pixels in your PNG are filled with the background colour (usually white) during conversion. If you need transparency, use PNG, WebP, or AVIF.
Is WebP supported by all browsers?
All modern browsers support WebP including Chrome, Firefox, Safari (14+), and Edge. For maximum compatibility, use a <picture> element with a JPEG fallback.
Does FluxToolkit upload my images?
No. All conversion happens in your browser. Your images are never sent to our servers.
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- Resize Image Online Guide — Scale dimensions alongside format conversion.
- WebP vs PNG vs JPG — Deep dive into format differences and when to use each.
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- Image to Base64 Guide — Embed converted images directly in CSS or HTML.