Modern computing depends heavily on data compression. Whether you are streaming a video, storing photos, or sending a document over the internet, compression algorithms shrink the amount of data required. This saves bandwidth and storage but can also affect quality if the technique is lossy. The compression ratio tells you exactly how much smaller the compressed file is compared to its original size. Mathematically, the ratio is represented as . A larger number means more aggressive compression.
Simply enter the original file size and the size after compression. The calculator then divides the original by the compressed amount to find the ratio. It also computes the percentage of space saved, calculated as multiplied by 100. A table appears below the result illustrating typical ratios for common file types so you can see how your data compares.
Some algorithms sacrifice exact fidelity for higher ratios. JPEG images, MP3 audio, and most video codecs fall into this category. Others preserve every bit, like ZIP archives or PNG graphics. The choice depends on whether perfect reconstruction is required. This calculator works for either scenario because it only needs the final file sizes. Keep in mind that extremely high ratios for lossy formats can degrade quality beyond acceptable limits.
A ten megabyte document compressed down to two megabytes has a ratio of 5:1, meaning it is five times smaller. In percentage terms, you saved 80% of the space. Compare that with a large raw photo that starts at 25 MB and compresses to 5 MB. The ratio is also 5:1, but whether the resulting image looks satisfactory depends on the method used. The table below lists common scenarios.
| File Type | Typical Ratio |
|---|---|
| Text (ZIP) | 2:1 – 5:1 |
| Raw Images to JPEG | 5:1 – 10:1 |
| Uncompressed Video to H.264 | 20:1 – 50:1 |
Use these values only as a rough guide. Actual results depend on the content and compression settings.
Compression is an essential part of digital life. By understanding ratios and percentages, you can choose the right balance between file size and quality. This calculator helps you quantify those trade-offs quickly and privately in your browser.
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