Convert data storage between decimal units (KB, MB, GB, TB, PB) and binary units (KiB, MiB, GiB, TiB, PiB) — and see exactly why they don't match.
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| Decimal Unit | Bytes | Binary Unit | Bytes |
|---|---|---|---|
| 1 Kilobyte (KB) | 1,000 | 1 Kibibyte (KiB) | 1,024 |
| 1 Megabyte (MB) | 1,000,000 | 1 Mebibyte (MiB) | 1,048,576 |
| 1 Gigabyte (GB) | 1,000,000,000 | 1 Gibibyte (GiB) | 1,073,741,824 |
| 1 Terabyte (TB) | 1,000,000,000,000 | 1 Tebibyte (TiB) | 1,099,511,627,776 |
| 1 Petabyte (PB) | 1,000,000,000,000,000 | 1 Pebibyte (PiB) | 1,125,899,906,842,624 |
A data storage converter changes a measurement of digital storage capacity from one unit to another — bits and bytes, and their decimal (KB, MB, GB, TB, PB) or binary (KiB, MiB, GiB, TiB, PiB) multiples. Unlike most physical units, storage has two competing systems of "kilo," "mega," and "giga," so converting between them requires knowing which system each side is using.
There are two different definitions of "kilo," "mega," and "giga" in computing, and mixing them up is the single most common source of confusion in data storage:
That mismatch is exactly why a drive advertised as "1TB" (1,000,000,000,000 bytes, decimal) shows up in Windows as roughly 931 "GB" — really GiB — of usable space. No storage is missing; the same number of bytes is just being counted in a bigger unit.
Decimal (SI) units scale by powers of 1,000 from the byte:
| Unit | Bytes |
|---|---|
| Kilobyte (KB) | 1,000 |
| Megabyte (MB) | 1,000,000 |
| Gigabyte (GB) | 1,000,000,000 |
| Terabyte (TB) | 1,000,000,000,000 |
| Petabyte (PB) | 1,000,000,000,000,000 |
Binary (IEC) units scale by powers of 1,024 from the byte:
| Unit | Bytes |
|---|---|
| Kibibyte (KiB) | 1,024 |
| Mebibyte (MiB) | 1,048,576 |
| Gibibyte (GiB) | 1,073,741,824 |
| Tebibyte (TiB) | 1,099,511,627,776 |
| Pebibyte (PiB) | 1,125,899,906,842,624 |
Data storage conversions come up when buying storage and comparing advertised capacity across drives, estimating cloud storage or bandwidth pricing that's billed per GB or TB, checking file sizes against upload or attachment limits, comparing RAM specifications, and understanding why a freshly formatted "1TB" hard drive shows less than 1,000 GB of usable space in your operating system.
A KB (kilobyte) is a decimal unit equal to 1,000 bytes, following the SI standard. A KiB (kibibyte) is a binary unit equal to 1,024 bytes, following the IEC standard. They are close but not the same — a KiB is about 2.4% larger than a KB.
Drive manufacturers advertise capacity using decimal TB (1 TB = 1,000,000,000,000 bytes), but Windows reports capacity using binary math while labeling it "GB" or "TB" when it technically means GiB or TiB. Since a GiB (1,073,741,824 bytes) is larger than a GB (1,000,000,000 bytes), the same number of bytes produces a smaller number when counted in GiB — so a 1TB drive shows as roughly 931 GiB (labeled "GB") in Windows.
A decimal gigabyte (GB) is 1,000,000,000 bytes. A binary gibibyte (GiB) is 1,073,741,824 bytes.
There are 8 bits in a byte.
No. 1 GB (decimal) equals 1,000 MB. 1,024 MiB equals 1 GiB (binary). The "1024" figure is correct for binary units, not decimal ones.
Decimal units follow the international SI standard used for every other unit of measurement (kilograms, kilometers, and so on), where "kilo" always means 1,000. It also makes advertised capacity numbers larger than the equivalent binary figure would be.
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