Image Formats Guide: Everything You Need to Know
There are dozens of image file formats, but only a handful matter for everyday use. This guide covers the 10 formats that FormatPic supports — the ones you are most likely to encounter and need to convert between. For each format, you will find what it is, how it compresses images, when to use it, and when to avoid it.
Quick reference: For photos, use JPG or WebP. For graphics with transparency, use PNG or WebP. For web optimization, use WebP. For iPhone photos, convert HEIC to JPG or WebP. For icons, use SVG or ICO.
Lossy vs. Lossless Compression
Before diving into individual formats, it helps to understand the two fundamental approaches to image compression:
Lossy compression analyzes an image and permanently discards visual information that human eyes are unlikely to notice. This produces dramatically smaller files — often 80–95% smaller than the uncompressed original — but the discarded information cannot be recovered. Each time you re-save a lossy file, additional information may be lost. JPG, WebP (lossy mode), HEIC, and AVIF all use lossy compression.
Lossless compression reduces file size by finding patterns in the data and encoding them more efficiently, without discarding any information. The original image can be reconstructed exactly from the compressed file. File sizes are larger than lossy equivalents, but image quality is preserved perfectly. PNG, GIF, BMP (uncompressed), TIFF, WebP (lossless mode), and SVG use lossless approaches.
The right choice depends on your priorities. For photographs where file size matters (web, email, social media), lossy compression at 80–90% quality produces results that are visually indistinguishable from the original. For graphics with text, sharp edges, or where pixel-perfect accuracy matters (logos, screenshots, technical diagrams), lossless compression is the better choice.
JPG / JPEG
Joint Photographic Experts Group · Extension: .jpg, .jpeg · MIME: image/jpeg
JPG is the most widely used image format in the world. Created in 1992 by the Joint Photographic Experts Group, it was specifically designed for compressing photographs. JPG uses Discrete Cosine Transform (DCT) compression — it divides the image into 8×8 pixel blocks, transforms the pixel values into frequency components, and then quantizes (rounds) the less perceptually important frequencies. This is why JPG compression artifacts appear as blocky patterns, especially at low quality settings.
JPG quality is controlled by a number from 1 to 100. At quality 100, very little data is discarded and the file is large. At quality 75–85 (the sweet spot for most web use), files are dramatically smaller with negligible visible quality loss. Below quality 50, compression artifacts become clearly visible.
Supports transparency: No. Any transparent areas will be filled with a solid color (usually white) when saving as JPG.
Supports animation: No.
Best for: Photographs, natural images, social media sharing, email attachments, product photos, and any image where universal compatibility matters.
Avoid when: You need transparency, the image contains text or sharp edges (use PNG instead), or you need pixel-perfect lossless quality.
PNG
Portable Network Graphics · Extension: .png · MIME: image/png
PNG was created in 1996 as a patent-free alternative to GIF (which used the patented LZW compression algorithm). It quickly surpassed GIF for static images thanks to its superior compression, full-color support, and alpha transparency.
PNG uses DEFLATE compression (the same algorithm used by ZIP files) to achieve lossless compression. Every pixel of the original image is preserved exactly. PNG also supports full alpha-channel transparency — each pixel can have a transparency value from 0 (fully transparent) to 255 (fully opaque), enabling smooth edges on logos, icons, and overlays.
The primary disadvantage of PNG is file size. A photograph saved as PNG will typically be 5–10 times larger than the same photograph saved as JPG, because PNG preserves every pixel without any perceptual simplification. For photographs on the web, PNG is almost never the right choice — JPG or WebP will produce a much smaller file with no visible difference.
PNG excels for images with flat colors, text, sharp edges, and transparency. Screenshots, logos, UI elements, diagrams, and graphics are where PNG shines. Its lossless nature also makes it ideal as an intermediate format during editing — you can save and re-open a PNG unlimited times without any quality degradation.
Supports transparency: Yes, full alpha channel.
Supports animation: APNG (Animated PNG) exists but has limited support.
Best for: Logos, icons, screenshots, graphics with text, images with transparency, intermediate editing format.
Avoid when: You are saving photographs for the web (use JPG or WebP instead) or need the smallest possible file size for photos.
WebP
Web Picture Format · Extension: .webp · MIME: image/webp
WebP was developed by Google and announced in 2010 as part of the WebM project. It uses the VP8 codec for lossy compression and a predictive coding method for lossless compression. WebP is designed specifically for web images, and it delivers on that goal — lossy WebP images are typically 25–34% smaller than equivalent JPGs, and lossless WebP images are 26% smaller than equivalent PNGs.
What makes WebP particularly versatile is that it combines features from both JPG and PNG into a single format. It supports both lossy and lossless compression, full alpha transparency (in both modes), and animation. This means WebP can replace JPG, PNG, and GIF for the vast majority of web image use cases.
Browser support for WebP has reached approximately 97% globally as of 2026. Every major browser — Chrome, Firefox, Safari, Edge, and Opera — supports WebP natively. The remaining 3% consists primarily of very old browser versions that are rarely encountered in practice. For most websites, WebP can be used without a fallback.
The main limitation of WebP is ecosystem support outside of browsers. Some image editing software, social media upload forms, and document tools still do not accept WebP files. In these cases, converting WebP to JPG or PNG provides universal compatibility.
Supports transparency: Yes, in both lossy and lossless modes.
Supports animation: Yes — smaller than GIF for the same animation.
Best for: All web images. It is the recommended default format for websites in 2026, balancing quality, file size, and compatibility.
Avoid when: You need to share files with software that does not support WebP (older image editors, some mobile apps, document tools).
HEIC / HEIF
High Efficiency Image Container · Extension: .heic, .heif · MIME: image/heic
HEIC is the format every iPhone owner encounters whether they know it or not. Since iOS 11 in 2017, Apple has used HEIC as the default photo format for all iPhones and iPads. It uses the HEVC (H.265) video codec — the same technology used for 4K video — to compress still images, achieving roughly 50% smaller files than JPEG at the same visual quality.
HEIC supports features that JPG does not: 16-bit color depth (vs. 8-bit for JPG), HDR imaging, transparency, and the ability to store multiple images in a single file (which is how iPhone Live Photos work — the still image and short video clip are both stored in one HEIC file).
The critical limitation of HEIC is compatibility. Web browsers cannot display HEIC images natively. Windows requires a separate extension from the Microsoft Store. Many image editors, social platforms, and websites do not accept HEIC uploads. This makes HEIC-to-JPG conversion one of the most common image conversion tasks — and it is the single most popular conversion on FormatPic.
The HEVC codec used by HEIC is covered by patents held by several companies (through the MPEG-LA patent pool), which has slowed its adoption outside the Apple ecosystem. This patent situation is one reason why royalty-free alternatives like WebP and AVIF have gained support from browser vendors.
Supports transparency: Yes.
Supports animation: Yes (HEIF sequences).
Best for: iPhone/iPad photography (automatic), storage-efficient archival on Apple devices.
Avoid when: Sharing photos with non-Apple users, uploading to websites, or using in any context outside the Apple ecosystem. Convert to JPG or WebP first.
AVIF
AV1 Image File Format · Extension: .avif · MIME: image/avif
AVIF is the newest format on this list and offers the best compression efficiency available today. Developed by the Alliance for Open Media (a consortium that includes Google, Mozilla, Microsoft, Apple, Amazon, and Netflix), AVIF uses the AV1 video codec for still image compression. It is completely royalty-free, unlike HEIC.
In compression benchmarks, AVIF consistently produces files 30–50% smaller than JPEG and approximately 20% smaller than WebP at equivalent visual quality. It supports HDR (both PQ and HLG transfer functions), wide color gamut (BT.2020), 12-bit color depth, and full alpha transparency. These features make AVIF the technically superior format for nearly any use case.
The downsides are practical rather than technical. AVIF encoding is computationally intensive — encoding an image takes longer than JPG or WebP. Browser support, while growing rapidly, is not yet universal. Chrome, Firefox, and Safari (since version 16.4) all support AVIF, but some older browser versions and image editing tools do not.
For web developers, AVIF is best used as a progressive enhancement: serve AVIF to browsers that support it, with WebP or JPG as fallbacks. This can be done using the HTML <picture> element or server-side content negotiation.
Supports transparency: Yes.
Supports animation: Yes (AVIF sequences).
Best for: Performance-critical websites, progressive enhancement, HDR content, future-proofing image assets.
Avoid when: You need universal compatibility today, fast encoding times, or support in older software.
GIF
Graphics Interchange Format · Extension: .gif · MIME: image/gif
GIF is one of the oldest image formats still in widespread use, introduced by CompuServe in 1987. It is best known for animated images — the looping, short-form animations that have become a staple of internet culture. GIF uses LZW compression (lossless) and supports up to 256 colors per frame from a 24-bit palette.
The 256-color limit is GIF's defining constraint. For photographs or images with gradients, this limit produces visible banding and dithering artifacts. For simple graphics, icons, and animations with flat colors, the limit is less of an issue.
GIF supports binary transparency (a pixel is either fully transparent or fully opaque — no partial transparency) and animation (multiple frames with configurable delays). While animated GIFs are ubiquitous on the web, they are extremely inefficient compared to modern alternatives. A 5-second animated GIF might be 5–20 MB, while the same animation as a WebP or short video file would be under 1 MB.
For new projects, WebP animations or short video clips (MP4) are almost always better choices than animated GIF. GIF remains relevant primarily for legacy compatibility and the cultural expectation of the format in messaging apps and social platforms.
Supports transparency: Binary only (no semi-transparency).
Supports animation: Yes — its primary modern use case.
Best for: Simple animations, memes, legacy compatibility, simple graphics with few colors.
Avoid when: You need more than 256 colors, semi-transparency, or efficient animation. Use WebP or video instead.
SVG
Scalable Vector Graphics · Extension: .svg · MIME: image/svg+xml
SVG is fundamentally different from every other format on this list. While JPG, PNG, and WebP are raster formats that store images as grids of colored pixels, SVG is a vector format that describes images as mathematical shapes — lines, curves, rectangles, circles, and text. This means an SVG image can be scaled to any size without any loss of quality, from a 16×16 favicon to a billboard-sized print.
SVG files are written in XML (a text-based markup language), which means they can be opened and edited in a text editor. They can be styled with CSS, animated with CSS animations or JavaScript, and embedded directly in HTML documents. This makes SVG uniquely powerful for interactive web graphics.
For logos, icons, and illustrations, SVG produces far smaller files than raster equivalents while maintaining perfect quality at any resolution. A logo that might be 50 KB as a PNG could be 3 KB as an SVG. However, SVG is not suitable for photographs — representing photographic detail as vector shapes would produce enormous files.
Supports transparency: Yes.
Supports animation: Yes (CSS and SMIL animation).
Best for: Logos, icons, illustrations, charts, diagrams, interactive graphics, responsive design elements.
Avoid when: Working with photographs or photographic images. Use JPG, WebP, or AVIF instead.
BMP
Bitmap Image File · Extension: .bmp · MIME: image/bmp
BMP is an uncompressed (or minimally compressed) raster format developed by Microsoft for Windows. A BMP file stores the color value of every single pixel without any compression, resulting in very large files — a 1920×1080 image at 24-bit color is about 6 MB as BMP versus 300 KB as JPG.
Despite its inefficiency, BMP has a niche: exact pixel preservation. Since no compression is applied, BMP files are guaranteed to contain exactly the pixel data they were created with. Some scientific, medical, and industrial imaging applications use BMP for this reason. BMP is also deeply embedded in the Windows ecosystem and supported by every Windows application.
For general use, there is almost no reason to use BMP. PNG provides the same lossless quality with much smaller file sizes. If you encounter BMP files (often from legacy systems or older Windows applications), converting them to PNG preserves quality while reducing file size by 50–80%.
Supports transparency: Limited (32-bit BMP with alpha channel, rarely used).
Supports animation: No.
Best for: Legacy Windows applications, exact pixel preservation for scientific/medical imaging.
Avoid when: Possible. Convert to PNG for the same quality at a fraction of the file size.
TIFF
Tagged Image File Format · Extension: .tiff, .tif · MIME: image/tiff
TIFF is the professional standard for high-quality image storage and exchange. Created by Aldus Corporation in 1986 (now maintained by Adobe), TIFF is used extensively in publishing, printing, professional photography, and archival imaging.
TIFF supports multiple compression methods (LZW, ZIP, JPEG, and none), multiple image layers, 16-bit and 32-bit per channel color depths, and multiple pages within a single file. This flexibility makes it extremely versatile for professional workflows but results in complex files and large sizes.
In professional photography, TIFF is often used as the archival format: a photographer edits a RAW file in Lightroom or Capture One, then exports the final result as a 16-bit TIFF for archival and as a JPG for delivery. The TIFF preserves maximum quality and editing flexibility for future reprints or re-edits.
For web use, TIFF is not appropriate — browsers do not display TIFF files natively, and the files are too large. Converting TIFF to JPG, PNG, or WebP is necessary before publishing online.
Supports transparency: Yes (with alpha channels).
Supports animation: No (but supports multi-page documents).
Best for: Professional photography, print publishing, archival storage, medical and scientific imaging.
Avoid when: Publishing for web, sharing via email, or any context where file size matters. Convert to JPG or WebP for distribution.
ICO
Icon File Format · Extension: .ico · MIME: image/x-icon
ICO is a specialized format designed for one purpose: icons. It was introduced by Microsoft with Windows 1.0 in 1985 and remains the standard format for website favicons (the small icon displayed in browser tabs) and Windows application icons.
What makes ICO unique is its ability to contain multiple images at different sizes and color depths within a single file. A typical favicon.ico might contain versions at 16×16, 32×32, 48×48, and 256×256 pixels. The operating system or browser selects the most appropriate size for the display context.
Modern ICO files typically embed PNG data for larger sizes (48×48 and above) and uncompressed bitmap data for smaller sizes. For websites, many developers now use SVG favicons or PNG favicons alongside a legacy ICO file, but ICO remains necessary for maximum compatibility with older browsers and Windows taskbar icons.
Supports transparency: Yes.
Supports animation: No.
Best for: Website favicons, Windows application icons, browser tab icons.
Avoid when: You need a general-purpose image format. ICO is specifically for icons.
Quick Comparison Table
Which Format Should You Use?
Here are simple rules of thumb based on what you are working with:
- Photographs for the web: WebP (or JPG as a fallback)
- Photographs for print: TIFF or high-quality JPG
- Logos and icons: SVG for web, PNG for documents, ICO for favicons
- Screenshots: PNG (lossless, preserves text clarity)
- iPhone photos for sharing: Convert HEIC to JPG or WebP
- Maximum compression: AVIF with WebP fallback
- Animations: WebP (or MP4 video for longer/complex animations)
Convert Between Formats
FormatPic supports conversion between all 10 formats listed above — that is over 90 possible conversion combinations. All conversions happen in your browser, are completely free, and your files never leave your device. Start converting →