File Size Calculator
Convert file sizes between bytes, KB, MB, GB, and TB.
What is the File Size Calculator?
The File Size Calculator is a free browser tool that converts a file size from one unit into bytes, kilobytes, megabytes, gigabytes, and terabytes all at once. Type a number, pick its unit, and every equivalent value updates instantly.
It uses binary (base-1024) math, so 1 KB equals 1,024 bytes, 1 MB equals 1,048,576 bytes, and so on. This matches how operating systems and most storage tools report sizes, which is why a file shown as a round number in one unit often looks uneven in another.
Everything runs locally in your browser. There is no signup, no upload, and no data leaves your machine, so it works the same offline as it does online.
How to use the File Size Calculator
- 1Enter a numeric value in the Size field.
- 2Choose the unit that value is expressed in from the Unit dropdown: Bytes, KB, MB, GB, or TB.
- 3Read the five result cards, which show the same size converted to bytes, kilobytes, megabytes, gigabytes, and terabytes.
- 4Change the number or the unit at any time; the results recalculate automatically without a button press.
- 5Copy the value you need into a config file, ticket, or documentation.
What you can use it for
- Checking whether an upload fits inside a service limit expressed in a different unit, such as a 25 MB email attachment cap.
- Translating a byte count from a build log or API response into a human-readable MB or GB figure.
- Estimating storage or bandwidth costs when a provider quotes prices per GB but your data is measured in MB.
- Setting size thresholds in scripts or CI pipelines that expect raw byte values.
- Verifying that an asset bundle stays under a performance budget defined in kilobytes.
Key features
- Converts to all five units (bytes, KB, MB, GB, TB) from a single input.
- Uses binary base-1024 conversion to match operating-system reporting.
- Live recalculation as you type, with no submit step.
- Byte totals are shown with thousands separators for easier reading.
Frequently asked questions
How many bytes are in a kilobyte, megabyte, and gigabyte?
This calculator uses binary units: 1 KB is 1,024 bytes, 1 MB is 1,048,576 bytes, and 1 GB is 1,073,741,824 bytes. Each step up multiplies by 1,024. This is the convention most operating systems and disk tools use.
Why does my file size look different on disk than what the file size calculator shows?
Storage vendors and some interfaces use decimal units where 1 MB equals 1,000,000 bytes, while operating systems use binary units of 1,048,576 bytes. This calculator uses the binary convention, so its numbers match Windows, macOS, and Linux file properties rather than marketing capacity figures.
Is the file size calculator free and does it require an account?
Yes, it is completely free with no account or signup. The conversion runs entirely in your browser, so nothing is uploaded and the tool keeps working even without an internet connection.
Can I convert a value from MB to GB or KB to bytes?
Yes. Enter the value, select its current unit, and the tool shows the equivalent in all five units simultaneously, so any conversion between bytes, KB, MB, GB, and TB is covered in one step.
Does the file size calculator accept decimal numbers?
Yes. You can enter fractional values like 1.5 or 0.25, and the tool converts them accurately. Gigabyte and terabyte results are shown with extra decimal places so small fractions remain visible.
Does this tool actually measure a file, or just convert numbers?
It converts a size value you type in; it does not read or inspect an actual file. To convert a real file, first check its size in your file manager, then enter that number and unit here.