Byte Converter (KB, MB, GB, TB)
Convert bytes, KB, MB, GB and TB — decimal and binary side by side, plus why a 1 TB drive shows 931 GB.
Converted in your browser — nothing is sentConvert bytes to KB, MB, GB and TB — decimal and binary side by side
Decimals: use a period or a comma — 1.5 or 1,5.
| Unit | Decimal — SI (1 KB = 1000 bytes) | Binary — IEC (1 KiB = 1024 bytes) |
|---|
Why there are two kinds of gigabyte
Quick answer: 1 GB is 1,000,000,000 bytes in the decimal (SI) system that drive makers, macOS and network speeds use, and 1,073,741,824 bytes (1024³) in the binary system Windows and RAM use — that second one is properly called a gibibyte, GiB. Pick any amount and unit above and the table shows it in every unit, decimal and binary side by side. Starting from 1 TB it shows the classic surprise: 931.32 GiB, which Windows displays as “931 GB”.
Nothing is missing from that drive: 1 TB is 1,000,000,000,000 bytes either way, and the “lost” 9% is only the difference between dividing by 1000 and by 1024, compounded at every step — a KiB is 2.4% larger than a KB, a MiB 4.9%, a GiB 7.4% and a TiB 10%. Internet-speed units (Mb, megabits) convert too, because plans are sold in bits and downloads are shown in bytes: 100 Mbps is 12.5 MB/s. Everything runs in your browser.
Data storage units chart
| Below the kilobyte | Size |
|---|---|
| Bit (b) | One binary digit: 0 or 1 |
| Nibble | 4 bits — one hexadecimal digit |
| Byte (B) | 8 bits — one ASCII character |
| Decimal unit (SI) | Bytes | Binary unit (IEC) | 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 |
| Petabyte (PB) | 1,000,000,000,000,000 | Pebibyte (PiB) | 1,125,899,906,842,624 |
| Exabyte (EB) | 10¹⁸ | Exbibyte (EiB) | 1,152,921,504,606,846,976 |
| Zettabyte (ZB) | 10²¹ | Zebibyte (ZiB) | 1,180,591,620,717,411,303,424 |
| Yottabyte (YB) | 10²⁴ | Yobibyte (YiB) | 1,208,925,819,614,629,174,706,176 |
| Ronnabyte (RB) | 10²⁷ | — | — |
| Quettabyte (QB) | 10³⁰ | — | — |
Ronna and quetta were added to the SI in November 2022; there are no binary equivalents yet. Each decimal step is ×1000 and each binary step is ×1024.
Why drives look smaller in Windows
| Sold as | Bytes | Windows shows | macOS shows |
|---|---|---|---|
| 128 GB | 128,000,000,000 | 119 GB | 128 GB |
| 256 GB | 256,000,000,000 | 238 GB | 256 GB |
| 500 GB | 500,000,000,000 | 465 GB | 500 GB |
| 512 GB | 512,000,000,000 | 476 GB | 512 GB |
| 1 TB | 1,000,000,000,000 | 931 GB | 1 TB |
| 2 TB | 2,000,000,000,000 | 1.81 TB | 2 TB |
| 4 TB | 4,000,000,000,000 | 3.63 TB | 4 TB |
| 8 TB | 8,000,000,000,000 | 7.27 TB | 8 TB |
Windows divides by 1024 at each step and cuts the result to three digits, so a 2 TB drive (1.819 TiB) reads 1.81 TB. The formatted capacity is a little lower still, because the file system reserves some space for itself.
Internet speed: Mbps to MB/s
| Plan (Mbps) | Download (MB/s) | 1 GB file takes at least |
|---|---|---|
| 10 | 1.25 | 13 min 20 s |
| 50 | 6.25 | 2 min 40 s |
| 100 | 12.5 | 1 min 20 s |
| 300 | 37.5 | 27 s |
| 500 | 62.5 | 16 s |
| 1000 (1 Gbps) | 125 | 8 s |
Excel / Google Sheets, bytes in A2:
=A2/10^9 → decimal gigabytes (GB)
=A2/1024^3 → binary gigabytes (GiB, what Windows shows)
Internet speed in Mbps in B2:
=B2/8 → MB/sReference tables
FAQ
Is 1 KB 1000 or 1024 bytes?
Both are in use. By the SI and IEC standards, 1 KB (kilobyte) is 1000 bytes and 1 KiB (kibibyte) is 1024 bytes. Drive makers, macOS and network speeds use 1000; Windows and RAM sizes use 1024 but still write “KB”, which is where the confusion comes from.
Why does my 1 TB hard drive show 931 GB?
The drive holds 1,000,000,000,000 bytes, as advertised. Windows divides by 1024 three times instead of 1000, gets 931.32, and labels it “GB”. macOS divides by 1000 and shows 1 TB for the same drive. A 500 GB drive shows as 465 GB and a 256 GB SSD as 238 GB for the same reason.
What is the difference between Mb and MB?
Lowercase b is bits, uppercase B is bytes, and a byte is 8 bits. Internet plans are sold in megabits per second (Mbps); downloads show megabytes per second (MB/s). Divide by 8: 100 Mbps is 12.5 MB/s, so a 5 GB file takes about 6 minutes 40 seconds at best.
How many bytes are in a gigabyte?
1,000,000,000 in decimal (GB) or 1,073,741,824 in binary (GiB). A terabyte is 1,000,000,000,000 bytes; a tebibyte is 1,099,511,627,776.