Large image files slow down websites, eat storage space, and make sharing cumbersome. The good news is that you can dramatically reduce image file sizes with little to no visible quality loss. Here is how.
Understanding Image Compression
There are two types of compression:
Lossless compression removes redundant data without discarding any visual information. The decompressed image is pixel-for-pixel identical to the original. PNG and WebP (lossless mode) use this approach.
Lossy compression discards some visual data that the human eye is unlikely to notice. This achieves much smaller file sizes but is irreversible — you cannot recover the discarded data. JPG and WebP (lossy mode) use this approach.
For more detail on how different formats handle compression, see our guide: Image File Formats Explained.
Method 1: Convert to a More Efficient Format
The single most impactful step is often choosing the right format:
PNG to WebP — WebP lossless images are typically 26% smaller than PNG with identical quality. Best for web use.
PNG to JPG — If your image does not require transparency, converting to JPG can reduce file size by 50-80%. See our PNG vs JPG comparison.
BMP to PNG — If you have uncompressed BMP files, converting to PNG provides lossless compression at a fraction of the size.
JPG to WebP — Modernise your photos with 25-34% smaller files for web use.
TIFF to JPG — Reduce print-quality TIFF files for web and email use.
BMP to JPG — Shrink uncompressed bitmaps dramatically.
HEIC to JPG — Convert iPhone photos to universally compatible, well-compressed JPG format.
PNG to AVIF — Next-gen format, up to 50% smaller than JPEG with equivalent quality.
Use our image converter or image compressor to try any of these conversions for free.
Method 2: Use Smart Compression
Modern compression algorithms can reduce file sizes significantly while preserving visual quality:
JPG quality 80-85 — This sweet spot typically reduces file size by 60-70% compared to quality 100, with differences invisible to the naked eye.
PNG optimisation — Tools can recompress PNG files more efficiently, often reducing size by 20-40% without any quality change.
WebP lossy at quality 80 — WebP's lossy mode at quality 80 produces files that are 70-80% smaller than uncompressed PNG with excellent visual quality. Convert with our PNG to WebP tool.
Method 3: Resize Your Images
Before compressing, consider whether your image is larger than it needs to be:
A 4000×3000 pixel photo displayed at 800×600 on a website is wasting 96% of its pixels.
Resize to the actual display dimensions before compressing for maximum file size reduction.
For specific size targets, use our tools: resize to 100KB, resize to 50KB, or resize to 200KB.
Method 4: Strip Metadata
Image files often contain hidden metadata — EXIF data from cameras, colour profiles, thumbnails, and editing history. Stripping this metadata can save 10-50 KB per image without affecting visual quality at all.
Method 5: Use the Right Format for the Right Context
Different situations call for different formats and compression levels:
Website images: Convert to WebP for best performance. See our website image optimisation guide.
Email attachments: Compress for email — stay under 25 MB Gmail limit.
Government forms: Resize to exact KB targets for portal uploads.
Printing: Keep high resolution — use TIFF or high-quality JPG.
Real-World Results
Here is what you can typically achieve with smart compression:
| Original | Conversion | Result | Savings |
|---|---|---|---|
| 5 MB PNG screenshot | PNG to WebP lossless | ~3.7 MB | 26% |
| 5 MB PNG screenshot | PNG to WebP lossy q85 | ~400 KB | 92% |
| 5 MB PNG screenshot | PNG to JPG q85 | ~500 KB | 90% |
| 3 MB JPG photo | JPG to WebP q80 | ~800 KB | 73% |
| 3 MB HEIC photo | HEIC to JPG | ~600 KB | 80% |
Results vary depending on image content. Photographs compress better than screenshots; simple graphics compress better than complex textures.
Frequently Asked Questions
What is the best image format for small file sizes?
For photos, WebP lossy produces the smallest files at excellent quality. For next-gen compression, AVIF is even smaller. For graphics with transparency, WebP lossless is smaller than PNG. See our complete format comparison.
How much can I compress a PNG without losing quality?
Converting PNG to WebP lossless reduces size by ~26% with zero quality loss. Converting PNG to JPG at quality 85 reduces size by 60-80% with minimal visible difference in photographs.
Does compressing images affect SEO?
Yes — positively. Smaller images improve page load speed, which is a confirmed Google ranking factor. Optimised images also improve Core Web Vitals scores. Convert to WebP for the best web performance.
What is the best free image compressor?
FileConvertTool offers free image compression and format conversion. Convert between PNG, JPG, WebP, AVIF, and more — no signup required. For specific size targets, use resize to 100KB.
How do I compress images for a website?
Convert to WebP for all modern browsers. Resize to display dimensions. Use quality 80-85 for lossy compression. See our complete website image optimisation guide.
Conclusion
Reducing image file sizes does not have to mean sacrificing quality. By choosing the right format, applying smart compression, and sizing images appropriately, you can achieve dramatic file-size reductions while keeping your images looking great.
Start converting: PNG to JPG · PNG to WebP · JPG to WebP · HEIC to JPG · Compress Images · Image Converter
For the complete guide to all image formats, read: Image File Formats Explained.