"Should I save this as JPG or PNG? I heard WebP is smaller but has compatibility issues? What's AVIF? What's the difference between SVG and bitmap?" — format selection wastes time on every export.
This cheat sheet uses "one-sentence decision" logic: Photo → JPG, Transparency → PNG, Web image → WebP, Animation → GIF/WebP, Icons → SVG, Smallest possible → AVIF. Master this and 90% of format decisions become instant.
01 Six Major Formats in One Sentence Each
JPG (JPEG): King of lossy compression. Best for photos and color-rich images. Supports 16M colors, no transparency. Small files, best compatibility (100% browser/device support). .jpg and .jpeg are identical.
PNG: Lossless compression standard. Best for images needing transparent backgrounds, screenshots, text graphics, icons. Supports alpha channel (semi-transparency). Files 3–8× larger than JPG. Two modes: PNG-8 (256 colors) and PNG-24 (16M colors).
WebP: Modern format by Google. Supports both lossy and lossless compression, transparency, and animation. 25–35% smaller than JPG, 26% smaller than PNG. Full support in all modern browsers (except IE). Safe to use for web as of 2024.
GIF: Ancient format with only 256 colors but supports frame animation. Good for simple animations and memes. Terrible for photos (severe color limitation). Large files. Being replaced by WebP and APNG.
SVG: Vector format, essentially XML code. Scaled infinitely without blur. Best for icons, logos, illustrations, data visualization. Not for photos. Tiny files (typically <10 KB). Controllable via CSS/JS.
AVIF: Image format derived from AV1 video codec. Highest compression ratio — 20%+ smaller than WebP. Supports HDR, wide gamut, transparency. Browser support exceeds 90% (2024). Downside: slow encoding.
02 Quick Lookup by Scenario: Which Format for Which Use Case?
Product photos/portraits → JPG (small files, good colors). For smallest possible → WebP. Hero images/banners → WebP (best modern browser performance), fallback JPG.
Logos/icons → SVG (lossless scaling), fallback PNG. Screenshots/text graphics/UI mockups → PNG (sharp text edges, no compression artifacts).
Transparent product images → PNG-24 (standard) or WebP (smaller). E-commerce detail pages → JPG at 80–85% quality (optimal balance of clarity and load speed).
Memes/simple animations → GIF (best compatibility) or WebP animation (smaller). High-quality animation → APNG. Social media sharing → JPG (widest support, least re-compression degradation).
Technical docs flowcharts/architecture → SVG (scalable for details), or PNG (universal). Email images → JPG/PNG (email clients have poor support for new formats).
If you really can't decide: Photos → JPG, everything else → PNG. This simple rule covers 80% of cases. Optimize the remaining 20% as needed.
03 Common Format Conversion Mistakes
Myth 1: Converting JPG to PNG improves quality. Completely wrong — JPG's lossy compression permanently discards information. Converting to PNG just losslessly encodes already-degraded data. File size increases several-fold with zero quality improvement.
Myth 2: WebP has compatibility issues. In 2024, all major browsers (Chrome, Firefox, Safari, Edge) fully support WebP. The only holdout, IE, was discontinued in 2022. Safe to use for web.
Myth 3: SVG scales infinitely so everything should be SVG. SVG is only for graphic content (lines, shapes, text). Photos can't be converted to SVG — forced conversion either creates multi-MB files or completely distorts the image.
Myth 4: AVIF is the best so use it everywhere. AVIF encoding is slow (10×+ slower than WebP), unsuitable for real-time compression. Some older devices also decode slowly. Best used for pre-encoded static assets.
FAQ
Should I choose WebP or AVIF?
In 2024, use WebP as default — great compatibility, fast encoding, mature ecosystem. Use AVIF when chasing minimal file sizes (like image CDNs for large-scale sites). If you're not doing massive-scale image optimization, WebP is more than sufficient.
Do I need to convert HEIC photos from iPhone?
Yes, for web uploads. HEIC is Apple's proprietary format with limited browser support. Convert to JPG (max compatibility) or WebP (smallest file). Apple devices usually auto-convert to JPG when sharing.
What's the difference between PNG-8 and PNG-24?
PNG-8 supports max 256 colors, very small files, good for simple icons and color blocks. PNG-24 supports 16M colors + full alpha channel, larger files, good for photo-quality images needing transparency. Selectable in Photoshop export.
Should animations use GIF or WebP?
WebP animations are typically 30–50% smaller than equivalent GIFs. But GIF has wider compatibility (email, legacy systems). Social sharing → GIF (more universal), website embedding → WebP animation (smaller, faster).
What's the fundamental difference between SVG vectors and bitmap images?
Bitmaps (JPG/PNG etc.) are pixel grids that blur when enlarged. SVG describes shapes with math formulas, staying crisp at any scale. But SVG can only express geometric shapes and text, not natural photos — their use cases don't overlap.
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This cheat sheet uses "one-sentence decision" logic: Photo → JPG, Transparency → PNG, Web image → WebP, Animation → GIF/WebP, Icons → SVG, Smallest possible → AVIF. Master this and 90% of format decisions become instant.