A data storage converter that separates decimal and binary sizes
This data storage converter turns a file, drive or download size between bits and bytes, the decimal units KB, MB, GB, TB, PB and EB (powers of 1,000) and the binary units KiB, MiB, GiB, TiB, PiB and EiB (powers of 1,024). The two families are kept in separate groups so you can see exactly where the “missing” space on a new drive went.
It answers the questions people actually have: why a 1 TB hard drive shows as 931 GB in Windows, how many megabytes a 100 Mbps connection downloads per second, how big 16 GB of RAM is in bytes, or whether a 25 MB email limit fits a 24.5 MiB attachment. Every answer is exact — data units are defined by whole powers of 10 and 2, so there is no rounding in the factors.
How to use the Data Storage Converter
- Type a size in the Value box, for example 500 or 1.5.
- Pick the unit you have in From. Search “GB”, “GiB” or “Mb” — capital B means bytes, small b means bits.
- Pick the unit you want in To; the round swap button reverses the direction.
- Read the result and formula, raise Precision to see every digit of a large byte count, and press Copy.
- Compare all units in the list below, grouped into bits, decimal bytes and binary bytes. Tap a row to make it the target unit.
Data Storage Converter features
Decimal and binary side by side
KB/MB/GB/TB (×1,000) and KiB/MiB/GiB/TiB (×1,024) are listed in separate groups with their symbols.
Bits for network speeds
Kilobits, megabits, gigabits and terabits, so broadband and Wi-Fi speeds convert straight into MB per second.
Exact large numbers
Byte counts up to 2⁵³ are shown in full — 1 PiB is exactly 1,125,899,906,842,624 bytes.
Explains the 931 GB mystery
The default example converts 1 TB into binary units so you can see the difference instantly.
Copy-ready values
Copy plain numbers without separators for spreadsheets, scripts and config files.
Decimal vs binary units
In the International System of Units, kilo means 1,000, mega 1,000,000 and giga 1,000,000,000 — and storage makers use exactly those meanings. But computer memory is addressed in powers of two, so for decades programmers used “kilobyte” to mean 1,024 bytes. To end the confusion, the International Electrotechnical Commission introduced binary prefixes in 1998: kibi (Ki), mebi (Mi), gibi (Gi), tebi (Ti) and so on, now part of the IEC 80000-13 standard.
| Decimal unit | Bytes | Binary unit | Bytes | Difference |
|---|---|---|---|---|
| Kilobyte (KB) | 1,000 | Kibibyte (KiB) | 1,024 | 2.4% |
| Megabyte (MB) | 1,000,000 | Mebibyte (MiB) | 1,048,576 | 4.9% |
| Gigabyte (GB) | 10⁹ | Gibibyte (GiB) | 1,073,741,824 | 7.4% |
| Terabyte (TB) | 10¹² | Tebibyte (TiB) | 1,099,511,627,776 | 10.0% |
| Petabyte (PB) | 10¹⁵ | Pebibyte (PiB) | 1,125,899,906,842,624 | 12.6% |
Why does a 1 TB drive show 931 GB?
A drive sold as 1 TB holds 1,000,000,000,000 bytes. Windows divides that by 1,024³ (1,073,741,824) to report gigabytes, gets 931.32, and labels the result “GB” even though it is really GiB. Nothing is missing — the same number of bytes is being counted with a bigger unit. The gap grows with size: a 2 TB drive shows about 1,863 “GB”, and a 4 TB drive about 3.64 “TB”.
Formatting then takes a little more for the file system’s own bookkeeping, and some phones and laptops reserve space for the operating system, which is why usable space is lower still. macOS and some Linux file managers report sizes in decimal units, so the same drive shows close to 1 TB there.
Bits, bytes and internet speed
A byte is 8 bits. Internet plans and Wi-Fi are sold in bits per second (Mbps, Gbps), while browsers and download managers show bytes per second (MB/s). Divide by 8 to compare: a 100 Mbps connection can move at most 12.5 MB per second, so a 1 GB file takes at least 80 seconds. Real downloads are a little slower because of protocol overheads. Test your actual speed with the internet speed test.
Worked example: a phone plan gives 2 GB of data a day. That is 2,000 MB, or about 1,907 MiB in binary terms — enough for roughly 13 minutes of a 20 Mbps video stream (20 Mbps is 2.5 MB/s, and 2,000 ÷ 2.5 = 800 seconds).
Common data size conversions
| From | To |
|---|---|
| 1 B | 8 bit |
| 1 KB | 1,000 B |
| 1 KiB | 1,024 B |
| 1 MB | 1,000 KB |
| 1 GB | 1,000 MB |
| 1 GiB | 1,024 MiB |
| 1 GiB | 1.073741824 GB |
| 1 TB | 931.3225746 GiB |
| 500 GB | 465.6612873 GiB |
| 1 TiB | 1.099511628 TB |
| 100 Mb | 12.5 MB |
| 1 Gb | 125 MB |
Data Storage Converter FAQ
How many MB are in a GB?
In decimal (SI) units, 1 GB = 1,000 MB. In binary units, 1 GiB = 1,024 MiB. Storage makers and network speeds use the decimal meaning; Windows and RAM sizes use the binary one, often still written as GB.
Why does my 1 TB hard drive only show 931 GB?
Because the drive is labelled in decimal terabytes (10¹² bytes) but Windows reports binary gibibytes (2³⁰ bytes each) while calling them GB. 10¹² ÷ 2³⁰ = 931.32. The data storage converter shows both units side by side.
What is the difference between GB and GiB?
A gigabyte (GB) is 1,000,000,000 bytes; a gibibyte (GiB) is 1,073,741,824 bytes, about 7.4% more.
How do I convert Mbps to MB/s?
Divide by 8, because there are 8 bits in a byte. 100 Mbps ÷ 8 = 12.5 MB/s, and 1 Gbps ÷ 8 = 125 MB/s.
Is a kilobyte 1,000 or 1,024 bytes?
Officially 1,000 bytes. The 1,024-byte unit is properly called a kibibyte (KiB), although older software and RAM specifications still use “KB” for it.
How many bytes are in a terabyte?
A terabyte is 1,000,000,000,000 bytes (10¹²). A tebibyte is 1,099,511,627,776 bytes (2⁴⁰).