Images are usually the heaviest thing on a web page. Optimising them is the single highest-leverage performance win for most sites.
Pick the right format
- JPG — photographs and complex imagery.
- PNG — graphics needing transparency or sharp edges.
- WebP — modern format with excellent compression for both.
- SVG — logos and icons that must scale crisply.
Compress intelligently
Most images can be compressed by 60–80% with no perceptible quality loss. The trick is choosing a quality level that removes invisible data while preserving detail — exactly what the Image Compressor recommends for you.
Serve responsibly
Use width and height attributes to prevent layout shift, lazy-load below-the-fold images, and provide responsive sources so each device downloads an appropriately sized file.
Lossy vs lossless at a glance
| Format | Best for | Compression | Transparency |
|---|---|---|---|
| JPG | Photographs, gradients | Lossy, tunable | No |
| PNG | Graphics, text, screenshots | Lossless | Yes |
| WebP | Web photos and graphics | Lossy or lossless | Yes |
| SVG | Logos, icons, diagrams | Vector (tiny) | Yes |
A repeatable optimization workflow
- Resize first: match the largest display width, never ship 4000px into a 400px slot.
- Compress second: target the quality where size drops sharply with no visible damage.
- Compare sizes: if WebP is over 30% smaller at equal quality, ship WebP with a JPG fallback.
- Confirm visually at 100%, not at a zoomed-out thumbnail.
A file-size budget habit
Think of image weight as a budget you allocate per page, not per file. A 200 KB hero on a landing page full of 40 KB cards is fine; a 200 KB hero on a page with nine more 200 KB images is a page that makes phones sweat. Set a per-image ceiling by role — thumbnail, card, hero, full-bleed — and let the ceiling, not laziness, decide when to switch formats or lower quality. Weigh the saved kilobytes against the visible trade before you decide a JPEG is “fine” at 95% quality when it also looks fine at 78%.
- Thumbnails under 20 KB; hero images under 250 KB are achievable for most photos.
- Downgrade in steps, not jumps: one dialog pass of 5% quality steps shows where it breaks.
- Once your tool set the ceiling, a quick checkbox pass per new asset keeps the site honest.
Frequently asked questions
Image optimization is the process of choosing the right format, compressing the file, and sizing it correctly so web pages load fast without sacrificing visible quality.
WebP is the modern default for most cases, offering strong compression. Use PNG when you need sharp transparency, JPG for photos at very small sizes, and SVG for logos and icons that must scale.
Most photos can be compressed 60-80% with no perceptible loss. The key is choosing a quality level that removes invisible data while keeping the detail you actually notice.
