How to reduce image file size (without the guesswork)
Smaller images mean faster pages, lower bandwidth bills, and better Core Web Vitals. These are the techniques that actually move the number, ordered from biggest impact to smallest.
Five ways to shrink an image, by impact
- 1
Resize to display size
A photo shown at 600px but delivered at 3000px carries ~25× the necessary data. Resizing to actual display dimensions is almost always the largest single saving.
- 2
Convert to a modern format
WebP is ~25–35% smaller than JPEG; AVIF is often ~50% smaller. Switching format compounds with resizing.
- 3
Compress appropriately
Use moderate lossy compression for photos and lossless for graphics. Maximum compression is for thumbnails and feeds.
- 4
Strip metadata
Remove EXIF unless you need it — it’s pure overhead for most web images and can leak location data.
- 5
Serve responsive sizes
Generate several widths and let srcset deliver the right one per device, so phones don’t download desktop-sized images.
What kind of savings to expect
Unoptimized JPEG and PNG assets commonly drop 40–80% once resized and converted to a modern format. The exact figure depends on the source, but the order of operations matters: resize first (it removes pixels), then convert (a more efficient codec), then compress (fine-tune quality). Doing them together in one pass avoids re-encoding artifacts.
Do it in one pass, at any scale
Optimagio resizes, converts, and compresses in a single step — for one image in the browser or a 50,000-file batch via the API.
Frequently asked questions
What is the fastest way to reduce image file size?
Resize the image to the dimensions it’s actually displayed at. Serving images larger than their rendered size is the most common and most wasteful cause of large files, so resizing usually saves more than any compression setting.
How much can I reduce image size without losing quality?
Commonly 40–80% for unoptimized JPEG/PNG assets, by resizing to display size and converting to WebP or AVIF, with no visible quality loss at normal viewing sizes.
In what order should I optimize an image?
Resize first (removes pixels), then convert to a modern format (more efficient codec), then compress to fine-tune quality. Doing them in one pass avoids repeated re-encoding.
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