Storage Size Converter — bytes, KB, MB, GB, TB

How it works

To convert a data size between units, express both units in bytes and take the ratio:

result = value × (bytes per from-unit ÷ bytes per to-unit)

This converter uses the decimal (SI) prefixes, where each step up is a factor of 1,000:

• 1 kilobyte (KB) = 1,000 bytes = 10³ B
• 1 megabyte (MB) = 1,000 KB = 10⁶ B
• 1 gigabyte (GB) = 1,000 MB = 10⁹ B
• 1 terabyte (TB) = 1,000 GB = 10¹² B

These are the units storage makers and networks quote — a "1 TB" drive holds 10¹² bytes. Operating systems sometimes report sizes with the binary prefixes (kibibyte, mebibyte, gibibyte), which step by 1,024, so a 1 TB drive shows as about 0.91 TiB. This tool uses the decimal definitions.

Worked example

1 GB in megabytes is 1 × (10⁹ ÷ 10⁶) = 1,000 MB. Going the other way, 500 MB is 500 × (10⁶ ÷ 10⁹) = 0.5 GB. A 1 TB drive is 1,000 GB, or 1,000,000 MB.

Frequently asked questions

How many MB are in a GB?

1,000 MB, using the decimal (SI) prefixes that storage and networking use: 1 GB = 10⁹ bytes and 1 MB = 10⁶ bytes, so 1 GB ÷ 1 MB = 1,000. Under the binary definition (1 GiB = 1,024 MiB) it is 1,024, but drives and bandwidth are quoted decimally.

What is the difference between decimal and binary prefixes?

Decimal prefixes (KB, MB, GB) step by 1,000; binary prefixes (KiB, MiB, GiB) step by 1,024. Storage capacity and data rates are quoted in decimal units, while some operating systems display file sizes in binary units, which is why a 1 TB drive can show as about 931 GB.

How many bytes are in a terabyte?

One terabyte is 10¹² bytes — 1,000,000,000,000 bytes — under the decimal definition. That is 1,000 gigabytes or one million megabytes. The binary tebibyte (TiB) is 2⁴⁰ bytes, about 10% larger.

Why does my hard drive show less space than advertised?

The drive maker counts a "1 TB" drive as 10¹² bytes (decimal), but your operating system may divide by 1,024s (binary), reporting about 931 GiB. No space is missing — it is two different definitions of the same number of bytes.

How many KB are in a MB?

1,000 KB, using the decimal prefixes: 1 MB = 10⁶ bytes and 1 KB = 10³ bytes, so 1 MB ÷ 1 KB = 1,000. Under the binary definition a mebibyte is 1,024 kibibytes, but storage and file transfers are quoted decimally.

What unit should I use for a file size?

Small files are convenient in kilobytes (KB) or megabytes (MB); photos and videos in megabytes or gigabytes (GB); and disks and large backups in gigabytes or terabytes (TB). Pick the unit that keeps the number readable — 4 GB is clearer than 4,000 MB — and this converter moves between them.