Image Compressor
Upload an image and compress it using a quality slider. See the before/after comparison and KB reduction display, then download the compressed image.
Image Compressor
Compress images instantly in your browser
Click or drag image here
Compressed image reduces file size by lowering JPEG quality (for JPG) or compression level (for PNG). The quality slider controls the balance between file size and visual fidelity.
How Image Compression Works
Image compression reduces file size by adjusting the compression parameters:
**JPG compression**: The JPEG format uses discrete cosine transform (DQ) and quantization. Lower quality values mean more aggressive quantization, which: - Removes high-frequency detail (fine textures, subtle color gradations) - Introduces compression artifacts (blocking, ringing near sharp edges) - Reduces file size proportionally to quality reduction
**PNG compression**: PNG uses zlib deflate compression. The compression level (0-9) controls: - Level 0: Fastest, largest output (minimal compression) - Level 9: Slowest, smallest output (maximum compression) - Level 6 is the default balance
**Quality trade-off guide**: - 100%: No visible difference from original, largest file - 80-90: Small file, very high visual quality, minimal artifacts - 60-70: Moderate file size, good for web, some artifacts possible - 40-50: Small file, noticeable artifacts, suitable for web only - Below 40: Significant artifacts, rarely used
- 100% private - images never uploaded to server
- Real-time quality preview
- Before/after comparison toggle
- JPG and PNG support
Worked Example
Example: Compressing a 2MB photograph for web use:
Original JPG: 2.0 MB (85% quality source)
- Quality 100: 1.9 MB (0.1 MB reduction, nearly identical) - Quality 80: 650 KB (67% reduction, high visual quality) - Quality 60: 350 KB (82% reduction, good web quality, minor artifacts) - Quality 40: 180 KB (91% reduction, noticeable artifacts, web-only)
The calculator displays the estimated KB reduction in real-time as you move the slider, so you can choose the exact quality point where the image still looks good at the desired file size.
JPG vs PNG Compression
- **JPG**: Photographs, complex color gradients, images without transparency. Compression is based on discarding imperceptible visual data. - **PNG**: Graphics, logos, images with text or transparency areas. Compression is based on deflate algorithm (same as ZIP files). PNG is lossless - no quality degradation regardless of compression level, but file sizes are typically larger than JPG at equivalent visual quality. - This calculator supports both formats and adjusts the compression algorithm based on the input file type.
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Open calculator →Frequently Asked Questions
Will image compression reduce the file size significantly?
Yes. Typical compression can reduce JPG files by 50-80% at high visual quality (80-90 on the slider). PNG files see more modest reduction (20-40%) since they're already compressed losslessly.
Can I compress an image and still maintain sharp text?
Yes, especially at quality levels 80+. For images with text, PNG format is recommended as it preserves sharp edges losslessly. At JPG quality 80+, text remains crisp in most cases.
What's the difference between compressing once vs. multiple times?
Compressing an already-compressed image (e.g., another JPG pass) introduces generation loss each time. It's best to start with the highest-quality source image possible and compress once to your target size.
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