Web image compression is a balancing act — reduce the file size enough to load fast without making the image look bad. The good news is that you can typically reduce image file size by 60–80% with no visible quality loss using the right technique.
Lossy vs Lossless Compression
There are two types of image compression: lossy (removes some image data — JPG, WebP) and lossless (compresses without removing data — PNG, WebP lossless). For photos, lossy compression at 80–85% quality is completely invisible to the human eye and can reduce file size by 80%. For graphics with text and sharp edges, use lossless compression to preserve clarity.
Optimal Quality Settings by Format
| Format | Quality Setting | Typical Size Reduction |
|---|---|---|
| JPG (photos) | 80–85% | 70–80% reduction |
| PNG (lossless) | N/A | 20–40% reduction |
| WebP (photos) | 80–85% | 75–85% reduction |
How to Compress for Web at imgresizr.com
Upload your image to imgresizr.com. First, resize to the dimensions at which it will display on your website — there is no point serving a 4000px image in a 800px-wide column. Then use the Compress tool. For JPG photos, 82% quality is a good starting point — it is nearly indistinguishable from 100% quality but 5–7× smaller. For PNG graphics, use the lossless compressor to shave 30–40% off without changing a single pixel.
The Secret Sauce: Resize First, Then Compress
- Step 1: Resize to display dimensions (never serve images larger than they display)
- Step 2: Choose the right format (JPG for photos, PNG for graphics)
- Step 3: Apply compression at 80–85% for JPG or lossless for PNG
- Step 4: Test on your website — load time should improve dramatically
Compress images for web at imgresizr.com with zero quality loss — free, instant, and works on every image format.