How to Compress Website Images Without Making Them Look Bad
The most effective order is dimensions first, format second, and quality last. Moving only a quality slider often saves less than resizing an oversized source to what the layout actually needs.
Start with dimensions, not the quality slider
A 6000×4000 camera photo remains expensive to transfer and decode even at a modest JPEG quality. If the layout never shows it wider than 1200px, reducing the longest edge to around 2400px can save more than lowering quality alone, while creating fewer visible artifacts. The 2× allowance serves dense screens; it is a planning point, not a law for every design.
| Page use | Typical output plan | Watch for |
|---|---|---|
| Article image | Prepare 1× and 2× around the content width | Let srcset choose |
| Full-width hero | Several widths around the max layout | Keep the LCP image lean |
| Thumbnail list | Generate dedicated small files | Do not shrink huge originals with CSS |
| Icon or logo | Prefer SVG; otherwise PNG/WebP | Preserve edges and alpha |
Choose format and quality for the content
Try WebP first for photographs, with JPEG as a compatibility fallback. For screenshots and transparent graphics, begin with PNG or lossless WebP. Consider AVIF for high-traffic, image-heavy pages where the delivery stack can maintain fallbacks. tinysqueeze Smart auto searches each JPEG/WebP/AVIF for a lower quality that still reaches its SSIM target, which helps when a batch contains varied material.
Make the browser download only what it needs
- Use
srcsetandsizesto describe width variants so small screens avoid oversized downloads. - Use
loading="lazy"below the fold, but do not lazy-load the main above-the-fold image. - Set explicit
widthandheightto reduce layout movement. - Write useful alt text for meaningful images; use empty alt for decoration and avoid keyword stuffing.
- Cache immutable versioned files for a long time, and change the URL when image content changes.
Compression is only one layer of delivery. If the browser still downloads the wrong dimensions, or the first viewport triggers dozens of images, the savings from each encoded file can be erased by an inefficient loading strategy.
A practical release checklist
- List the ten largest images on an important page instead of starting with the whole media library.
- Record their real display sizes and create matching 1×/2× outputs in tinysqueeze.
- Inspect clarity, crop, transparency, and text edges on phone and desktop.
- Update dimensions, srcset, alt text, and cache versions in the markup.
- After release, confirm in the Network panel that a phone actually receives the smaller source.
References
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