Data Storage Converter

Convert between decimal SI units (base 1000) and binary IEC units (base 1024) with complete discrepancy comparisons.

Value

From Unit

SI Decimal System (Base 1000)1 KB = 10³ B

Bits (b)

8000000000

Nibbles

2000000000

Bytes (B)

1000000000

Kilobytes (KB)

1000000

Megabytes (MB)

1000

Gigabytes (GB)

Terabytes (TB)

0.001

Petabytes (PB)

0.000001

Exabytes (EB)

1.000000e-9

Zettabytes (ZB)

1.000000e-12

Yottabytes (YB)

1.000000e-15

IEC Binary System (Base 1024)1 KiB = 2¹⁰ B

Bits (b)

8000000000

Nibbles

2000000000

Bytes (B)

1000000000

Kibibytes (KiB)

976562.5

Mebibytes (MiB)

953.674316406

Gibibytes (GiB)

0.931322574615

Tebibytes (TiB)

0.000909494701773

Pebibytes (PiB)

8.881784e-7

Exbibytes (EiB)

8.673617e-10

Zebibytes (ZiB)

8.470329e-13

Yobibytes (YiB)

8.271806e-16

SI vs. IEC Capacity Discrepancy

Scale Level	SI Marketed Value (Base 1000)	IEC Operating System Value (Base 1024)	Discrepancy (OS Loss Ratio)
Kilo / Kibi	1000000	976562.5	2.34%
Mega / Mebi	1000	953.674316406	4.63%
Giga / Gibi	1	0.931322574615	6.87%
Tera / Tebi	0.001	0.000909494701773	9.05%
Peta / Pebi	0.000001	8.881784e-7	11.18%
Exa / Exbi	1.000000e-9	8.673617e-10	13.26%
Zetta / Zebi	1.000000e-12	8.470329e-13	15.30%
Yotta / Yobi	1.000000e-15	8.271806e-16	17.28%

Discrepancy Explanation: Storage drive manufacturers advertise capacities in decimal base 1000 (e.g., 1 TB = 1,000,000,000,000 bytes). However, operating systems (like Windows) calculate space using binary base 1024 (Tebibytes). The shortfall is not a single figure — it compounds with each step, because it is exactly 1 − (1000/1024)ⁿ for the n-th prefix: 2.34% at kilo, 4.63% at mega, 6.87% at giga and 9.05%at tera. That is why a 1 TB drive shows up as about 931 GB (0.909 TiB) in your file manager: nothing is missing, the two systems are just counting in different bases.

Decimal vs. binary storage unit differences

Digital storage capacities are measured using two competing units standards. The International System of Units (SI) uses decimal prefix conversions: 1 KB = 1000^1 Bytes. This is standard for network bandwidth, marketing hard disk capacities, and USB flash memory chips.

Conversely, the International Electrotechnical Commission (IEC) standard defines binary subdivisions:1 KiB = 1024^1 Bytes, representing true powers of two (2¹⁰). This matches RAM capacities and file system storage descriptors in computer architecture.

Built and maintained by Meet Shah · Last updated 1 August 2026

What this tool is used for

Converting a size between bytes, megabytes and gigabytes.
Checking a file size against an upload limit in different units.
Comparing a drive's advertised capacity against reported free space.
Converting a size quoted in one unit into the unit a tool reports.
Adding several file sizes quoted in different units into one total.

Frequently Asked Questions

What is the difference between GB and GiB?: A gigabyte is 1,000³ bytes; a gibibyte is 1,024³. The IEC introduced the binary names in 1998 precisely because the same prefix was being used for both, and the gap widens at every step up the scale.
Why does my 1 TB drive show as 931 GB?: Because the manufacturer counts in decimal terabytes and the operating system displays binary ones. 1,000⁴ bytes divided by 1,024⁴ is 0.909, so a 1 TB drive genuinely holds what it says — Windows just labels GiB as GB.
How large is the discrepancy?: It is 1 − (1000/1024)ᵖ where p is the number of prefix steps, so it does not depend on the size at all: 2.4% at kilo, 4.9% at mega, 7.4% at giga, 9.9% at tera. Every 1 TB drive is short by the same 9.9%.
Which system does networking use?: Decimal, and in bits rather than bytes — a 100 Mbps link is 100,000,000 bits per second, about 11.9 MiB/s. That factor of eight, plus protocol overhead, is why a connection never downloads at the number in its name.
Which one should I use?: Whichever your audience expects, stated explicitly. Storage vendors and networking use decimal; RAM is always binary because addressing is; operating systems are inconsistent. Ambiguity is the problem, not the choice.
Why does RAM never show this mismatch?: Because memory is addressed in powers of two, so an 8 GB module really is 8 GiB and every layer counts it the same way. Storage has no such constraint, which is what let the two conventions diverge.

Common errors and gotchas

Mixing decimal and binary prefixes, where a gigabyte may mean 10^9 or 2^30 bytes.
Confusing bits with bytes, a factor of eight that appears throughout networking figures.
Being surprised a drive shows less than advertised, which is this difference and not a fault.
Rounding near a hard limit, where the boundary is exactly what matters.
Comparing a compressed size against an uncompressed one.