Resize and compress a website image: a practical comparison
Work through a 1600 × 1200 to 800 × 600 resize, compare JPEG and WebP, and check dimensions and visual quality before replacing your original.
A smaller image file helps only if it still serves its purpose. Product text must remain readable, a logo may need transparency, and a large display may need more pixels than a thumbnail. This workflow separates image dimensions from encoding quality so you can see which change helped.
Start with a copy and a measurable target
Use a non-sensitive 1600 × 1200 photo, or record the actual width and height of your own source. Save the original separately. For this exercise, the target display is 800 × 600 pixels. A source twice that width may still be useful on a high-density display, so choose the target from the real page layout rather than treating 800 pixels as a universal limit.
Record the starting dimensions and file size. Do not expect a fixed percentage reduction: results depend on the source image, detail, format and existing compression.
1. Resize while keeping the aspect ratio
Open Image Resizer, select the image, leave Lock Aspect Ratio enabled, and set the width to 800. For a 1600 × 1200 source, the height should become 600 because the scale factor is one half. Download the result and inspect its dimensions in your file viewer.
If the result is stretched, check whether the ratio lock was disabled. If it is blurred, compare the target dimensions with the actual display size. Enlarging a small source cannot recover detail that was never captured.
2. Compare formats using the same resized source
Open Image Compressor. First export JPEG at quality 80, then repeat from the same resized source using WebP at quality 80. These settings are a starting point, not a benchmark showing equal quality between encoders.
Compare actual file sizes, then zoom in on fine text, edges, faces and smooth gradients. Keep the smaller candidate only if it meets your visual needs. An already optimized source can become larger after re-encoding. Avoid compressing the previous lossy export repeatedly, because artifacts can accumulate.
3. Handle transparency intentionally
JPEG cannot preserve transparent pixels. For a transparent logo or icon, compare PNG and WebP in Image Converter, then inspect the result against both light and dark backgrounds. Photographic detail, transparency and sharp interface text are different requirements; one format does not win every case.
Canvas-based exports can also change or omit metadata. Keep the source if you need its camera information or other original properties. This workflow checks visible output and dimensions, not archival preservation.
4. Check the image on the actual page
Replace one image first and load the page on a phone and desktop. Verify that it is crisp at the rendered size, does not crop out important content, and has an appropriate text alternative. If you control the HTML, supply width and height or an aspect ratio to reserve space while the image loads. Responsive image variants can help serve different display sizes.
Keep a simple comparison log: source dimensions and bytes, resized dimensions and bytes, format and quality setting, and any visible defects. This gives you evidence for your choice without claiming that every image will save the same amount or that an image change guarantees a search-ranking improvement.