Why does your “1 TB” hard drive show up as 931 GB in Windows Explorer? It’s because storage vendors and operating systems use two different, equally valid conventions for the same unit names. This tool converts your value into every common unit under both systems simultaneously, so the discrepancy is never a mystery again.
What Is the File Size Converter?
Enter a value and a unit, and instantly see its equivalent in every common data size unit — from bytes up to petabytes — computed both the decimal (SI, 1000-based: KB/MB/GB/TB/PB) way and the binary (IEC, 1024-based: KiB/MiB/GiB/TiB/PiB) way, side by side.
How to Use It
- Open the tool at /tools/file-size-converter.
- Enter your value and select its unit.
- Compare the decimal (SI) and binary (IEC) conversion tables side by side.
Key Features
- Both unit systems at once, so you never have to guess which convention a number is using.
- Full unit range, from bytes through petabytes.
- Automatic scientific notation for extremely large or small results, keeping the display readable.
- Instant, live conversion as you type or change units.
When to Use This Tool
- Understanding why a drive’s advertised capacity doesn’t match what your OS reports.
- Converting file sizes for documentation, invoices, or technical specs that need to be unambiguous.
- Estimating storage or bandwidth requirements where the decimal vs. binary distinction actually matters.
Try It Now
Open File Size Converter directly, or press ⌘K and type the tool name from anywhere on the site.
Part of the Math & Numbers collection on WebdevToolbox — free, browser-based developer tools with no login required.