Data Storage Size Converter
Data storage sizes are expressed in two incompatible systems: SI decimal (where 1 KB = 1,000 bytes, used by storage manufacturers) and IEC binary (where 1 KiB = 1,024 bytes, used in computing and memory). This converter shows both simultaneously so you can understand the true size of any storage value. Enter a value and unit, and the calculator instantly shows the equivalent in bytes, all decimal SI prefixes (KB, MB, GB, TB, PB), and all binary IEC prefixes (KiB, MiB, GiB, TiB, PiB).
Decimal (SI) units
Binary (IEC) units
Data storage conversion factors
Decimal: 1 KB = 1,000 B | 1 MB = 1,000,000 B | 1 GB = 1e9 B | 1 TB = 1e12 B
Binary: 1 KiB = 1,024 B | 1 MiB = 1,048,576 B | 1 GiB = 1,073,741,824 B
IEC 80000-13 (2008) standardized the binary prefixes. Conversion routes through bytes for exact computation.
When each standard applies
- Hard drives and SSDs: Marketed using decimal GB and TB.
- RAM and flash memory chips: Sized in binary powers (GiB) even if labeled GB.
- Network speeds: Megabits per second (Mbps) use decimal SI.
- File sizes in operating systems: Windows traditionally used binary but displayed GB; macOS switched to SI decimal in 2009.
Data storage converter: frequently asked questions
What is the difference between a gigabyte and a gibibyte?
A gigabyte (GB) in the SI/decimal standard equals 1,000,000,000 bytes. A gibibyte (GiB) in the IEC binary standard equals 2^30 = 1,073,741,824 bytes. Hard drive manufacturers use GB (decimal); operating systems historically used binary units but called them GB, causing the apparent size discrepancy you see when formatting a drive.
Why does my 1 TB hard drive show less space on my computer?
Drive makers market 1 TB as 1,000,000,000,000 bytes (SI). Your OS converts this to binary: 1,000,000,000,000 / 2^40 = approximately 0.909 TiB, which it may display as 909 GB. This is not missing space; it is a units conversion difference.
What standard do memory (RAM) chips use?
RAM is manufactured and addressed in binary multiples. A 16 GB RAM stick contains exactly 2^34 = 17,179,869,184 bytes. The industry uses binary units for RAM even when labeling it in GB. This converter's binary tab shows the IEC prefixes (KiB, MiB, GiB, TiB).
What does KiB mean and how is it different from KB?
KiB (kibibyte, IEC 80000-13) = 2^10 = 1,024 bytes exactly. KB in practice means different things: in SI it is 1,000 bytes; in computing it has traditionally meant 1,024 bytes. IEC standardized KiB in 1999 to remove the ambiguity. This converter shows both.
How many bytes is a terabyte?
Decimal TB (SI): 1,000,000,000,000 bytes (10^12). Binary TiB (IEC tebibyte): 1,099,511,627,776 bytes (2^40). The difference is about 9.95%. Always check which standard a storage device uses; storage media uses decimal, memory and file sizes use binary.
Official sources
- IEC 80000-13:2008: NIST on IEC binary prefixes.
- BIPM SI Brochure: SI prefixes (kilo, mega, giga, tera).
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.