File Size Calculator – Convert Bytes, KB, MB, GB & More
About the File Size Calculator
The File Size Calculator instantly converts between bits, Bytes, Kilobytes, Megabytes, Gigabytes, Terabytes, and Petabytes using the binary (base-1024) standard that operating systems use to display file sizes. Drag and drop any file directly into the tool to see its exact size across every unit, or enter a value manually to convert between units on the fly.
It’s built for anyone checking upload limits, comparing storage plans, or converting file sizes for documentation and specs. Once you know your file’s size, the Storage & Bandwidth Calculator is useful for estimating monthly bandwidth or storage needs at scale, and the Pixel Calculator helps relate image dimensions to file size for web optimization.
The BigToolSite Team tested the drag-and-drop file reader and every unit conversion pair to confirm the results stay accurate down to very small and very large file sizes.
How to Use the File Size Calculator
- Drag and drop a file onto the drop zone, or click it to browse and select a file.
- Alternatively, enter a File Size value manually and choose its From Unit (bits, Bytes, KB, MB, GB, TB, or PB).
- View the converted value across all seven units instantly in the results grid.
- Click Copy on any result card to copy that specific converted value and unit.
Example Usage
Input: 1 file dropped, size shown as 5,242,880 Bytes
Output: 5.24 MB, 0.005 GB, 41,943,040 bits, and the equivalent value in KB, TB, and PB — all shown at once.
Manual Input: 2.5 GB
Output: 2,560 MB, 2,621,440 KB, 0.00244 TB.
Frequently Asked Questions
It uses the binary standard (1 KB = 1024 Bytes), which matches how most operating systems like Windows and macOS report file sizes, rather than the decimal (1000-based) standard used for network speeds.
Some providers use the decimal (base-1000) standard for storage and bandwidth billing, while this calculator and most file managers use the binary (base-1024) standard, which can create small differences in the displayed number.
Yes, use the manual input fields to enter any number and select its unit, and the tool will convert it across all seven size units without needing to upload anything.
No, the file is only read locally in your browser to determine its size — it’s never uploaded or transmitted anywhere.
Yes, it’s completely free with no signup required.
