💾 Data Storage

Data Storage Converter

Why is a "500 GB" drive only 465 GiB? Convert between decimal (1000-based) and binary (1024-based) data units to see exactly what your storage means. Press Convert to compare.

Written and reviewed by SM Arijul Islam · Last reviewed 28 October 2026 · Editorial standards · Report an error

Decimal vs binary units

Drive manufacturers use decimal prefixes (1 GB = 1,000,000,000 bytes) while most operating systems report binary values (1 GiB = 1,073,741,824 bytes). That gap of roughly 7% per step is why advertised capacity and reported capacity rarely match.

What the units mean

1 byte = 8 bits
1 KB = 1,000 bytes · 1 KiB = 1,024 bytes
1 MB = 10⁶ bytes · 1 MiB = 1,048,576 bytes
1 GB = 10⁹ bytes · 1 GiB = 1,073,741,824 bytes
1 TB = 10¹² bytes · 1 TiB = 1,099,511,627,776 bytes

Data transfer rates use bits, not bytes: 100 Mbps = 12.5 MB/s. Remember to divide by 8.

How to convert digital storage

Digital storage is counted in bits and bytes, where one byte holds eight bits. Two systems are in use at the same time: decimal (SI) units such as kilobyte, megabyte and terabyte that step up by 1,000, and binary units such as kibibyte, mebibyte and gibibyte that step up by 1,024. Drives are sold using decimal units while many operating systems report binary ones, which is the reason a nominal capacity can appear to shrink once it is formatted.

Common digital storage conversions

One gigabyte (10⁹) expressed in other units of digital storage
Unit	1 gigabyte (10⁹) equals
Kilobyte (1000) (KB)	1,000,000
Megabyte (10⁶) (MB)	1,000
Mebibyte (1024²) (MiB)	953.67432
Gibibyte (1024³) (GiB)	0.93132257
Terabyte (10¹²) (TB)	0.001
Tebibyte (1024⁴) (TiB)	0.0009094947

Everyday uses

Comparing drive, phone and memory-card capacity
Estimating download and upload times
Cloud storage plans and backups
Mobile data allowances and bandwidth
Video, photo and audio file sizes

Storage is quoted differently by manufacturers and operating systems. Always compare like with like before judging a capacity.

Common storage conversions

Everyday digital storage queries, all computed the same way as the converter above
Search-style query	Decimal answer	Binary note
1 GB in MB	1,000 MB	about 953.7 MiB in binary units
1 TB in GB	1,000 GB	about 931.3 GiB in binary units
500 GB in MB	500,000 MB	about 465.7 GiB on a computer
2 TB in GB	2,000 GB	about 1,862.6 GiB in binary units
100 MB to GB	0.1 GB	about 0.0977 GiB in binary units
1024 MB to GB	1.024 GB	1 GiB in binary units
100 Mbps to MB/s	12.5 MB/s	megabits per second divide by 8
mbps vs MB/s	Mbps is speed in bits; MB/s is size in bytes	divide Mbps by 8 to compare with MB/s

Frequently asked questions

Why does my 1 TB drive show about 931 GB?

Manufacturers use decimal units (1 TB = 1,000,000,000,000 bytes), while many systems report binary units (1 TiB = 1,099,511,627,776 bytes) — a difference of roughly 9%.

What is the difference between MB and MiB?

MB is a decimal megabyte, 1,000,000 bytes; MiB is a binary mebibyte, 1,048,576 bytes.

How many bits are in a byte?

Eight. That is why a 100 megabit-per-second connection moves about 12.5 megabytes per second.

Does a kilobyte mean 1,000 or 1,024 bytes?

Officially 1,000 — the 1,024 value is a kibibyte. Everyday usage is often looser than the standard.

More worked examples

A 500 GB drive holds 500,000,000,000 bytes, which is 465.66 GiB, and that is why the operating system reports about 465 GB.
One TiB is 1,024 GiB, or 1,099,511,627,776 bytes.
One GB is 1,000 MB in decimal terms, but 953.67 MiB in binary terms.
A 4 MiB photo is 4,194,304 bytes.

Decimal and binary units

Decimal and binary data units side by side
Decimal (SI)	Binary (IEC)
1 kilobyte (kB) = 1,000 bytes	1 kibibyte (KiB) = 1,024 bytes
1 megabyte (MB) = 1,000 kB	1 mebibyte (MiB) = 1,024 KiB
1 gigabyte (GB) = 1,000 MB	1 gibibyte (GiB) = 1,024 MiB
1 terabyte (TB) = 1,000 GB	1 tebibyte (TiB) = 1,024 GiB

Common mistakes to avoid

Expecting a drive advertised as 500 GB to show 500 GB in the file manager. Manufacturers use decimal units and most operating systems used binary ones.
Mixing MB and MiB inside one calculation. The gap is about 5 percent at the megabyte scale and about 7 percent at the gigabyte scale.
Assuming file sizes and network speeds use the same base. Storage marketing is decimal, and connection speeds are decimal too.
Confusing bits and bytes. A 100 Mbps connection is about 12.5 MB per second, because there are eight bits in a byte.

Further questions

Why does my hard drive show less space than advertised?

Two reasons. The maker uses decimal units, so 500 GB means 500 billion bytes, and the operating system historically divided by 1,024, which gives 465.66 GiB. Filesystem overhead takes a little more.

What is the difference between a GB and a GiB?

A gigabyte is 1,000,000,000 bytes and a gibibyte is 1,073,741,824 bytes, which is 1,024 mebibytes.

How many megabytes are in a gigabyte?

1,000 MB in decimal notation, or 1,024 MiB if you are working in binary units. Using the wrong base is a common source of confusion.

Are internet speeds measured in bits or bytes?

Bits. A speed quoted in Mbps is megabits per second, so divide by eight to compare it with a download size in megabytes.

Sources and standards

A byte is eight bits, but storage and memory count differently: SI prefixes are powers of ten, while the binary prefixes Ki, Mi and Gi are powers of two. NIST publishes the prefix rules, and the page shows both readings when a drive capacity is ambiguous.

GB to MB, MB to KB and TB to GB

How many MB in a GB has two correct answers: 1000 MB in decimal storage and 1024 MiB in the binary notation Windows uses. How many GB in a TB follows the same split — 1000 or 1024. That is why a 1 TB drive shows 931 GB in Windows, and why 1 TB to GB is quoted as 1,000 GB by manufacturers.

Data size equivalents in decimal and binary units
Value	Decimal	Binary (IEC)
1 MB to KB	1,000 KB	1,024 KiB
1 GB to MB	1,000 MB	1,024 MiB
1 TB to GB	1,000 GB	1,024 GiB
1 KB to bytes	1,000 bytes	1,024 bytes
1 byte to bits	8 bits, always

The dedicated pages GB to MB, TB to GB, KB to MB and bytes to bits explain the difference in full — including why a 100 Mbps connection downloads at 12.5 MB/s.