Data Storage Converter
MB, GB, TB — and why your computer shows a different number.
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1 GB = 1,000,000,000 bytes
The same size, read both ways
| Scale | Decimal (×1000) | Binary (×1024) | Gap |
|---|---|---|---|
| Kilo | 1,000,000 kB | 976,563 KiB | 2.4% |
| Mega | 1,000 MB | 953.674 MiB | 4.9% |
| Giga | 1 GB | 0.931323 GiB | 7.4% |
| Tera | 0.001 TB | 0.000909495 TiB | 10.0% |
| Peta | 0.000001 PB | 8.88178e-7 PiB | 12.6% |
Drives are sold using the first column. Windows shows the second column but still calls it “GB” — that’s where the “missing” space goes. Nothing is actually missing.
Broadband is advertised in megabits per second. Eight bits to a byte, so a 100 Mbps line moves about 12.5 MB per second at best.
to transfer 1 GB at 100 Mbps
The fastest it could possibly be. Real downloads are usually a bit slower.
1 GB in every other unit
- Bit (bit)8,000,000,000
- Kilobit (kbit)8,000,000
- Megabit (Mbit)
Broadband is sold in megabits per second, which is why a "100 Mb" line downloads at about 12.5 MB/s.
8,000 - Gigabit (Gbit)8
- Byte (B)1,000,000,000
- Kilobyte (kB)1,000,000
- Megabyte (MB)1,000
- Terabyte (TB)0.001
- Petabyte (PB)0.000001
- Kibibyte (KiB)976,562.5
- Mebibyte (MiB)953.6743
- Gibibyte (GiB)
What Windows and most tools call a "GB" when reporting a drive’s size.
0.9313226 - Tebibyte (TiB)0.0009094947
- Pebibyte (PiB)8.881784e-7
Your files stay on your device
How to use it
Enter a size like 1 TB to see it in MB, GB, and more — the way drives are sold and the way computers count — plus download times.
Bought a 1 TB drive and your computer says 931 GB? Nothing is missing. Drive makers count 1 GB as 1,000,000,000 bytes, but Windows counts it as 1,073,741,824 bytes — and still calls it “GB”. This tool shows both numbers side by side.
Enter a size and pick its unit to see it in every other unit.
Want to know how long a download will take? Enter your internet speed. Speeds are sold in megabits and files are measured in megabytes — 8 bits make a byte — so a 100 Mbps connection downloads at most 12.5 MB per second.
Macs, by the way, count the same way drive makers do, so the same drive shows as 1 TB on a Mac.
Decimal and binary, compared
What a drive is sold as, and what your computer will usually show.
| Sold as (decimal) | Reported as (binary) |
|---|---|
| 500 GB | 465.66 GiB |
| 1 TB | 931.32 GiB |
| 2 TB | 1.819 TiB |
| 4 TB | 3.638 TiB |
| 8 TB | 7.276 TiB |
| 16 TB | 14.55 TiB |
Bytes in each unit
The exact number of bytes in each unit. Every conversion here uses these, so the results are exact.
| Unit | Bytes |
|---|---|
| Kilobyte (kB) | 1,000 |
| Kibibyte (KiB) | 1,024 |
| Megabyte (MB) | 1,000,000 |
| Mebibyte (MiB) | 1,048,576 |
| Gigabyte (GB) | 1,000,000,000 |
| Gibibyte (GiB) | 1,073,741,824 |
| Terabyte (TB) | 1,000,000,000,000 |
| Tebibyte (TiB) | 1,099,511,627,776 |
Megabits and megabytes
Internet speeds are sold in megabits; files are measured in megabytes. Divide your speed by 8 for the fastest possible download rate.
| Connection speed | Best-case transfer |
|---|---|
| 10 Mbps | 1.25 MB/s |
| 50 Mbps | 6.25 MB/s |
| 100 Mbps | 12.5 MB/s |
| 500 Mbps | 62.5 MB/s |
| 1 Gbps | 125 MB/s |
FAQ
Why does my 1 TB drive only show 931 GB?
Your computer counts gigabytes in a slightly bigger unit but still calls them “GB”. The drive has its full space.
How many MB are in a GB?
1,000 the way drive makers count, or 1,024 the way most computers count.
What’s the difference between GB and GiB?
A GB is 1,000,000,000 bytes. A GiB is 1,073,741,824 bytes — about 7% more.
How long will my download take?
Enter the file size and your internet speed. The estimate is the best case; real downloads are a bit slower.
Is a megabit the same as a megabyte?
No. A megabyte is 8 megabits. Small “b” means bits; big “B” means bytes.
How it worksFor the curious
SI prefixes are powers of 1,000 (kB, MB, GB, TB). IEC binary prefixes are powers of 1,024 (KiB, MiB, GiB, TiB). Windows and most programming languages compute in binary but label with SI names. The gap grows at each step: 2.4% at kilo, 4.9% at mega, 7.4% at giga, 10% at tera. The IEC introduced GiB in 1998 to end the ambiguity.
macOS has reported storage in decimal units since OS X 10.6.
Download time divides by eight to convert bits to bytes and is a theoretical best case: protocol overhead, the server’s upload limit, and other traffic all make real transfers slower.