What this calculator does
Digital storage has two competing sets of units sharing the same names. Decimal units, kilobyte, megabyte, gigabyte, scale by powers of 1,000, the way a hard drive is usually marketed. Binary units, kibibyte, mebibyte, gibibyte, scale by powers of 1,024, the way an operating system usually reports the same storage.
That mismatch is why a drive sold as "1 TB" shows up as roughly 931 GiB in a file manager: no storage has gone missing, the two figures are simply counting in different-sized units for the same physical bytes.
The formula
This calculator keeps the two families separate: KB, MB, GB and TB scale by exactly 1,000 each step; KiB, MiB, GiB and TiB scale by exactly 1,024 each step, following the IEC binary-prefix standard introduced specifically to end the ambiguity. Both ultimately convert through the byte, which is itself 8 bits.
| Term | Meaning |
|---|---|
| Base unit | The byte (8 bits), which every other unit converts through. |
| Decimal prefix (KB, MB, GB…) | Scales by 1,000 per step: the convention used for marketing storage capacity. |
| Binary prefix (KiB, MiB, GiB…) | Scales by 1,024 per step: the convention operating systems typically use to report the same storage. |
The inputs explained
| Field | What to enter |
|---|---|
| Value | The value to convert. |
| From | The unit you are converting from. |
| To | The unit you want the answer in. |
When to use it
Working out why a drive shows less space than advertised
A drive marketed as 1 TB (1,000,000,000,000 bytes, decimal) reports as about 931 GiB in an operating system that counts in binary units: this calculator shows exactly where that gap comes from.
Sizing a file, download or backup
File sizes are usually shown in decimal units by web browsers and file listings alike, but understanding both scales avoids being caught out when planning storage or bandwidth close to a limit.
Converting a data rate or file size for a technical spec
Networking speeds are typically quoted in decimal bits or bytes per second, while memory capacity is typically quoted in binary units: this calculator handles both directions.
Understanding RAM versus storage figures
Computer memory (RAM) capacity is usually a true binary quantity by design, 8 GB of RAM is 8 GiB exactly, while storage drives are usually decimal, which is why RAM and disk figures are not directly comparable without conversion.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
One of each unit, converted to megabytes
A single unit of digital storage, each converted to decimal megabytes to compare true scale.
| From | In megabytes |
|---|---|
| Bit | 0.00000013 MB |
| Byte | 0.000001 MB |
| Kilobyte (10³) | 0.001 MB |
| Gigabyte (10⁹) | 1,000 MB |
| Terabyte (10¹²) | 1,000,000 MB |
| Kibibyte (2¹⁰) | 0.001024 MB |
| Mebibyte (2²⁰) | 1.048576 MB |
| Gibibyte (2³⁰) | 1,073.741824 MB |
Converting 1 GB to other units
A single decimal gigabyte, the unit storage is usually marketed in, expressed in the units it is more often reported in.
Questions
Why does my 1 TB drive show less than 1,000 GB in my computer?
The drive is marketed in decimal terabytes (10¹² bytes), but most operating systems display capacity in binary units, sometimes still labelled GB even though they mean GiB (2³⁰ bytes). The bytes are identical; only the counting convention differs, and the binary units are the larger measure per step.
What is the actual difference between a kilobyte and a kibibyte?
A kilobyte is 1,000 bytes; a kibibyte is 1,024 bytes: about 2.4 per cent more. The gap compounds at each step up, reaching almost 10 per cent by the gigabyte/gibibyte level and around 10 per cent again by terabyte/tebibyte.
Is RAM measured in decimal or binary units?
Binary, essentially always: memory chips are built in binary-sized blocks, so "8 GB of RAM" is a true 8 GiB (2³³ bytes) even though it is written with the decimal-looking label GB rather than GiB.
How many bits are in a byte?
Exactly 8. This is the one universally fixed relationship in digital storage: every conversion here treats a byte as 8 bits regardless of which prefix scale is in use.
Why were kibibyte, mebibyte and gibibyte introduced?
To remove the ambiguity of "kilobyte" meaning either 1,000 or 1,024 bytes depending on context. The IEC introduced KiB, MiB, GiB and so on in 1998 specifically to give the binary scale its own unambiguous names, leaving KB, MB and GB to mean the decimal values.
For a duration like a download or backup time, see the time converter. For the electricity a device draws while transferring or storing that data, use the electricity running cost calculator.