Choosing the wrong image format is one of the most common mistakes in web design, blogging, and digital content creation. Using a PNG for a photograph results in unnecessarily large files. Using a JPG for a logo with transparency produces a white box around it. Understanding what each format does — and when to use it — is a fundamental skill for anyone who works with images online.
This guide covers every major image file format: what it is, how it works, its strengths and weaknesses, and the specific situations where it is the right choice.
JPG (JPEG) — The Photograph Standard
Full name: Joint Photographic Experts Group
Extension: .jpg or .jpeg
Compression: Lossy
Transparency: Not supported
JPG is the most widely used image format in the world, and for good reason: it produces small file sizes for photographic content through lossy compression. Lossy means that some image data is permanently discarded when the file is saved — but at quality settings of 75–85, the discarded data is in the high-frequency detail range that the human eye is least sensitive to. A well-compressed JPG looks identical to its original at normal viewing distances.
Use JPG for: Photographs, product images, blog post hero images, social media photos, anything with complex colour gradients.
Avoid JPG for: Images with text (compression artefacts make text blurry), logos, icons, images with flat colours or sharp edges, anything requiring a transparent background.
Important: Never repeatedly re-save a JPG. Each save cycle adds more compression artefacts. Always keep a lossless master copy (PNG or TIFF) and export to JPG only for the final version.
PNG — Lossless Quality and Transparency
Full name: Portable Network Graphics
Extension: .png
Compression: Lossless
Transparency: Fully supported (alpha channel)
PNG uses lossless compression — it removes redundant data but preserves every single pixel exactly as it was in the original. This makes PNG the format of choice for images where quality cannot be compromised: logos, icons, screenshots, charts, and images with text overlays.
PNG also supports a full transparency channel (called an alpha channel), which allows pixels to be partially or fully transparent. This is essential for logos and icons that need to appear over different coloured backgrounds.
Use PNG for: Logos, icons, favicons, screenshots, images with text, graphics with flat colours, any image requiring transparency.
Avoid PNG for: Photographs intended for the web (PNG produces files 3–5× larger than equivalent JPG for photographic content).
You can generate all standard favicon sizes from a PNG source image using Rekreay's free Favicon Generator.
WebP — The Modern All-Rounder
Full name: Web Picture format
Extension: .webp
Compression: Both lossy and lossless modes
Transparency: Fully supported
WebP was developed by Google specifically for web use and represents a significant advancement over both JPG and PNG. At equivalent visual quality, WebP files are typically:
- 25–35% smaller than JPG for photographic content
- 26% smaller than PNG for lossless content
WebP supports both transparency and animation, making it a potential replacement for both PNG and GIF in modern web projects. Browser support is now essentially universal — all major browsers have supported WebP since 2020.
Use WebP for: All web images where you want the best quality-to-size ratio. Ideal for blog images, product photos, and any image displayed in a web browser.
Avoid WebP for: Email attachments (many email clients do not render WebP), print production, or environments where you cannot confirm WebP support.
Convert your JPG or PNG images to WebP using Rekreay's free Image Converter.
GIF — Animation and Legacy Support
Full name: Graphics Interchange Format
Extension: .gif
Compression: Lossless (but limited colour palette)
Transparency: Binary transparency only (a pixel is either fully transparent or fully opaque)
GIF is an old format (1987) with a significant limitation: it supports a maximum of 256 colours per frame. This makes it entirely unsuitable for photographs but acceptable for simple graphics and icons. Its defining feature is animation support — GIF files can contain multiple frames that play in sequence, making it the original format for animated images on the web.
Use GIF for: Simple animated images (memes, reaction GIFs, simple looping animations). For static images, PNG is almost always a better choice.
Avoid GIF for: Photographs, any image with more than 256 colours, static images where PNG is available, new animation projects (WebP animation and video formats are more efficient).
SVG — Scalable Vector Graphics
Full name: Scalable Vector Graphics
Extension: .svg
Compression: N/A (vector-based, not pixel-based)
Transparency: Fully supported
SVG is fundamentally different from all the other formats listed here. Instead of storing colour values for individual pixels, SVG stores mathematical descriptions of shapes, lines, curves, and fills. This means an SVG file looks perfectly sharp at any size — from a 16×16 favicon to a 10-metre billboard — because it is redrawn at whatever resolution is needed.
Use SVG for: Logos, icons, illustrations with flat colours, charts, diagrams, any graphic that needs to scale to multiple sizes without quality loss.
Avoid SVG for: Photographs (SVG cannot represent the complex pixel-level detail of photographic images efficiently).
Quick-Reference Format Selection Guide
- Photograph on a website → WebP (best) or JPG
- Logo or icon → SVG (vector) or PNG (if raster)
- Screenshot or image with text → PNG
- Favicon → PNG (32×32 or larger)
- Email attachment photo → JPG
- Animated image → WebP animation or GIF
- Image requiring transparency on a website → WebP or PNG
How to Convert Between Formats
If you have an image in one format and need it in another, Rekreay's free Image Format Converter handles JPG, PNG, and WebP conversions entirely in your browser. Upload your source image, choose the output format, and download the converted file — no software installation, no server upload, no cost.
Final Thoughts
The right image format choice reduces file sizes, preserves quality where it matters, and ensures your images display correctly in every context. Use JPG for photos, PNG for graphics with transparency, WebP for the web's best all-round performance, SVG for logos and icons, and reserve GIF only for animations. When in doubt, convert to the appropriate format using a free browser-based tool.