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We compressed 28 photos at 15 settings: the results
Going from JPEG quality 95 to 82 cut the typical photo’s file size by about half, while it stayed very similar to the original by a standard measure. Going lower saves less each step and costs more. Here are the numbers, and the raw data.
Updated October 30, 2026
The results for JPEG
Each row is the middle result (median) across all 28 photos, which were 10.8 megapixels at the median. “Saved” compares each photo with its own version at quality 95. Similarity runs from 0 to 1, where 1 means identical to the source.
| JPEG quality | Typical size (KB) | Saved | Similarity (SSIM) |
|---|---|---|---|
| 95 | 2,608 | 0% | 0.998 |
| 90 | 1,932 | 20% | 0.997 |
| 85 | 1,446 | 41% | 0.986 |
| 82 | 1,172 | 51% | 0.978 |
| 80 | 1,071 | 54% | 0.974 |
| 75 | 832 | 65% | 0.967 |
| 70 | 720 | 69% | 0.961 |
| 60 | 570 | 76% | 0.944 |
| 50 | 463 | 80% | 0.934 |
What we found
- The first cuts are the cheapest. Quality 95 to 82 saved about 51% and moved the similarity score from 0.998 to 0.978. Quality 60 to 50 saved only a little more, while the score fell from 0.944 to 0.934.
- WebP helps. WebP at quality 80 was about 26% smaller than JPEG at quality 82, with a similarity score about 0.009 lower.
- The same setting gives very different sizes. At JPEG quality 82, photos of plants ran about 178 KB per megapixel and food about 85 KB. Those groups are small (4 and 2 photos), but detailed scenes do cost more.
Quality alone rarely hits a small limit
Upload forms and web guides often ask for under 500 KB or 1 MB. Here’s how many photos got there with quality alone, at their full pixel size:
| JPEG quality | Under 500 KB | Under 1 MB |
|---|---|---|
| 82 | 1 of 28 | 7 of 28 |
| 75 | 4 of 28 | 17 of 28 |
| 60 | 10 of 28 | 25 of 28 |
| 50 | 17 of 28 | 26 of 28 |
For a small limit, reduce the pixel size first. Our compress to size tool does this for you, and shrinks the photo only if quality alone can’t reach your limit.
How we tested, and the limits
- Photos: 28 photographs from Wikimedia Commons, all marked CC0: people, landscapes, cities, night scenes, plants, food and indoor scenes.
- Encoders: MozJPEG and libwebp through the jSquash libraries, the same ones our tools use, run on a Mac on October 30, 2026.
- Similarity: SSIM on brightness only, with an 11-pixel window.
- Small sample: treat these as a guide, not a law. 28 photos can’t represent every kind of picture.
- Already-compressed sources: these are JPEG files as published, not camera originals, and that can flatter the scores at high settings.
- SSIM isn’t your eyes: it’s a math score. We didn’t run a test with human viewers, so we don’t claim which setting “looks the same.”
Get the data
Download the full results (CSV): every photo at every setting, with a link to each source image. Free to reuse; please link to this page if you cite it.