File Size Converter
Convert file sizes between bytes, KB, MB, GB, and TB. See binary (1024) and decimal (1000) conversions side by side instantly.
Binary (Base 1024)
Used by operating systems (Windows, Linux)
Decimal (Base 1000)
Used by storage manufacturers (SI standard)
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Understanding File Sizes
File sizes can be measured using two different systems, which often causes confusion. The binary system (base 1024) is used by operating systems, while the decimal system (base 1000) is used by storage manufacturers and follows the SI standard.
| Unit | Binary (1024) | Decimal (1000) |
|---|---|---|
| 1 KB / 1 KiB | 1,024 bytes | 1,000 bytes |
| 1 MB / 1 MiB | 1,048,576 bytes | 1,000,000 bytes |
| 1 GB / 1 GiB | 1,073,741,824 bytes | 1,000,000,000 bytes |
| 1 TB / 1 TiB | 1,099,511,627,776 bytes | 1,000,000,000,000 bytes |
This difference explains why a 1 TB hard drive shows as approximately 931 GiB in Windows. The manufacturer uses decimal (1 TB = 1,000,000,000,000 bytes) while Windows uses binary (1 TiB = 1,099,511,627,776 bytes).
Frequently Asked Questions
What is the difference between KB and KiB?
KB (kilobyte) uses decimal (1000 bytes), while KiB (kibibyte) uses binary (1024 bytes). Operating systems often display sizes in binary but label them as KB, which causes confusion.
Why do hard drives show less space than advertised?
Hard drive manufacturers use decimal (1 GB = 1,000,000,000 bytes) while operating systems use binary (1 GB = 1,073,741,824 bytes). A 1 TB drive shows as about 931 GB in Windows.
How many bytes are in a megabyte?
In decimal (SI): 1 MB = 1,000,000 bytes. In binary: 1 MiB = 1,048,576 bytes. This converter shows both systems side by side.
What is the largest file size unit?
Common units go up to TB (terabyte). Beyond that: PB (petabyte), EB (exabyte), ZB (zettabyte), and YB (yottabyte). This converter supports bytes through TB.
Last updated: June 2026