Image Compressor
Squeeze a photo down to a smaller file at the same pixel size, and see exactly how many bytes you saved.
Results
What this tool does
A camera photograph is usually several megabytes of detail that nobody will ever look at closely. Compressing it keeps the same width and height but spends fewer bytes describing them. Move the quality down until the picture still looks right to you, and the page tells you the new size, the old one, and the difference between them. Nothing is uploaded; the work is done by your own browser.
Formula
savings = (size before − size after) ÷ size before
Variables
| Symbol | Meaning | Unit |
|---|---|---|
quality | Quality | % |
bytes_in | Original size, in bytes | — |
bytes_out | New size, in bytes | — |
OUT | New file size | — |
BF | It was | — |
SV | Difference | — |
PC | Saved | % |
DR | Smaller or bigger | — |
Worked example
- Quality75 %
- Original size, in bytes2,400,000
- New size, in bytes380,000
- New file size371.1 kB
- It was2.29 MB
- Difference1.93 MB
- Saved84.2 %
- Smaller or biggerSmaller
Limitations
- The calculation runs entirely in your browser. The values you type are never sent to a server.
Frequently asked questions
Why does the same quality setting save different amounts on different photos?
Because JPEG spends its bytes on detail. A photograph of a brick wall or a forest is nearly all detail and stays large; a photograph of a clear sky or a plain studio background compresses to almost nothing at the same setting. The number you choose is how much detail to throw away, not how many kilobytes to end up with.
Why are the two byte boxes there if the file fills them in?
Opening an image fills them in for you, but they stay editable so the page is also a plain comparison of any two file sizes — useful when you already have a before and after from somewhere else and just want the percentage. The arithmetic is the same either way.