Image compression is the process of reducing an image's file size while preserving acceptable visual quality. Smaller images load faster on websites, consume less storage, and are easier to share over email or messaging apps. The Privatool Image Compressor reduces JPG, PNG, and WebP file sizes by up to 80% — entirely in your browser, with no file upload.
Lossy vs lossless compression
Lossy compression (JPG, WebP) permanently removes some image data to achieve smaller file sizes. The quality slider controls how much data is discarded. At quality 80, most people cannot see any difference compared to the original.
Lossless compression (PNG) reorganizes data more efficiently without removing any information. File size reduction is smaller (typically 10–30%) but quality is identical to the original.
| Format | Compression type | Best use |
|---|---|---|
| JPG | Lossy | Photos, complex images |
| PNG | Lossless | Screenshots, logos, text graphics |
| WebP | Both | Web images (modern browsers) |
How much can you compress?
Results vary by image content and the quality setting used:
| Image type | Typical size reduction |
|---|---|
| High-resolution photo (JPG) | 60–80% |
| Screenshot (PNG) | 20–40% |
| Logo with transparency (PNG) | 10–30% |
| WebP photo | 50–70% |
A 5 MB DSLR photo typically compresses to under 1 MB at quality 80 with no visible difference on screen.
Why file size matters for websites
Page load speed is a confirmed Google ranking factor. Images are typically the largest assets on a web page — unoptimized images are the single biggest cause of slow load times.
- Every 1-second delay in page load reduces conversions by ~7% (Akamai)
- Google's Core Web Vitals measure Largest Contentful Paint (LCP) — often an image
- Mobile users on slower connections are most affected by large images
The recommended maximum image file size for web use is 200 KB per image. Hero images can go up to 500 KB if necessary.
Quality slider guide
| Quality | File size | Visual quality |
|---|---|---|
| 60 | Very small | Noticeable artifacts on close inspection |
| 70 | Small | Minor artifacts on complex textures |
| 80 | Medium | No visible difference for most images |
| 90 | Large | Virtually indistinguishable from original |
| 95+ | Very large | No difference, not recommended for web |
80 is the recommended default for web publishing. Use 90+ only when images will be viewed at large sizes or printed.
Batch compression
The tool supports up to 5 images at once. Each image gets its own quality setting — you can compress a photo at 75 and a logo PNG at 90 in the same session. All compressed images download individually; use a ZIP tool to bundle them if needed.
Privacy: why no upload matters
Most image compression services — TinyPNG, Squoosh, Compressor.io — upload your images to their servers for processing. This means:
- Your images are transmitted over the internet
- They may be stored on third-party servers
- You depend on their uptime and privacy policies
Privatool compresses images using the browser-image-compression library running in WebAssembly directly in your browser. Your images never leave your device.
Comparing Privatool vs TinyPNG
| Feature | Privatool | TinyPNG |
|---|---|---|
| File upload | No — browser only | Yes — server upload |
| Free limit | Unlimited | 20 images/month |
| Batch size | 5 images | 20 images |
| Format support | JPG, PNG, WebP | JPG, PNG, WebP |
| Quality control | Manual slider | Automatic |
| Privacy | Files stay local | Files sent to servers |
How to compress images free
- Go to Image Compressor
- Upload up to 5 JPG, PNG, or WebP images
- Adjust the quality slider per image (default 80 is recommended)
- View before/after file size comparison in real time
- Download each compressed image
Related tools
- Image Resizer — resize to exact pixel dimensions before compressing
- Image Converter — convert PNG to WebP for even smaller web files
- Image Cropper — remove unnecessary parts of an image first
- PDF Compressor — reduce PDF file sizes the same way