Quality 90% (excellent)
- Input
- 4,2 MB JPEG original (12 MP)
- Expected output
- ~1,1 MB
Imperceptible difference in most photographs. Ideal for archiving.
compress JPG online
Compress JPG online: reduce photo size without visible quality loss
JPEG is the dominant format for digital photographs because it uses DCT (Discrete Cosine Transform) compression — a technique that discards color information imperceptible to the human eye. At 75–90% quality, the size reduction is significant and the visual difference is practically nonexistent. This tool processes the file entirely in the browser: no pixel is transmitted.
Continue in the tool
Open full toolHow JPEG compression works in practice
- JPEG compression divides the image into 8×8 pixel blocks and applies DCT to each block, converting pixel values into frequencies. High frequencies (fine details) are discarded more aggressively than low frequencies (large color areas). This is why sharp edges and text blur before large sky or skin areas are affected.
- Re-compression quality matters. A JPEG saved at 90% and then re-compressed at 90% is not the same as a JPEG saved at 90% once — each compression cycle accumulates artifacts. Always work from the highest-resolution original available.
- EXIF metadata can add 5 to 50 KB to the file. Re-encoding through the Canvas API removes them automatically, contributing to the final reduction — and eliminating information like GPS coordinates and device model.
Typical savings by quality level
Quality 80% (great)
- Input
- 4,2 MB JPEG original (12 MP)
- Expected output
- ~600 KB
Industry standard for web. Excellent quality/size balance.
Quality 60% (web/social)
- Input
- 4,2 MB JPEG original (12 MP)
- Expected output
- ~280 KB
Visible artifacts in gradients. Suitable for thumbnails and low-resolution previews.
Full tool FAQ
It depends on the compression level and format. Lossy formats like JPEG and WebP discard color information imperceptible to the human eye. At 75–90% quality, the difference is rarely visible — but aggressive compression below 60% introduces visible artifacts, especially on edges and gradient areas.
Frequently asked questions
What quality should I use to compress JPG without losing quality?
80–85% is the sweet spot for most photographs: significant size reduction with barely perceptible visual difference. For high-fidelity archiving, use 90%. For social media and thumbnails, 70–75% is acceptable.
Why did my compressed JPG end up larger than the original?
If the original was saved at very low quality, re-encoding it at high quality can produce a larger file. Use quality equal to or lower than the original. Also check that the original file does not have a .jpg extension but is actually another format.