Data Storage
Bytes, KB, MB, GB, TB, PB
The Data Storage Converter handles the units used to measure digital storage and bandwidth: bytes, kilobytes, megabytes, gigabytes, terabytes, and petabytes. It supports both the decimal (SI, base-10) and binary (IEC, base-2) interpretations, which differ by about 7% at the gigabyte scale and grow further apart at larger units.
Mixing the two is the source of the famous "why does my 1 TB drive only show 931 GB?" question.
Decimal vs binary
- Decimal (SI): 1 KB = 1,000 bytes, 1 MB = 1,000,000 bytes, etc. Used by storage manufacturers and networking standards.
- Binary (IEC): 1 KiB = 1,024 bytes, 1 MiB = 1,048,576 bytes, etc. Used by most operating systems when reporting file and disk sizes.
The IEC "binary" units have explicit names (kibibyte, mebibyte, etc.) to disambiguate, although most software still labels them as "KB" and "MB" anyway.
Conversion factors
- 1 KB (decimal) = 1,000 bytes; 1 KiB (binary) = 1,024 bytes
- 1 MB (decimal) = 1,000² bytes; 1 MiB (binary) = 1,024² bytes
- 1 GB (decimal) = 1,000³ bytes; 1 GiB (binary) = 1,024³ bytes
- 1 TB (decimal) = 1,000⁴ bytes; 1 TiB (binary) = 1,024⁴ bytes
Why a 1 TB drive looks smaller
The drive manufacturer measures 1 TB as 1,000,000,000,000 bytes. Windows (and most operating systems) divide that by 1,024³ to display it as gigabytes:
1,000,000,000,000 / 1,073,741,824 ≈ 931.32 GB
Both numbers describe the same physical storage. The drive is not "missing" anything — the labelling conventions just differ.
When this is useful
Planning storage upgrades, estimating backup sizes, comparing cloud storage quotas, sizing video or photo libraries, and understanding why a download progress bar uses one set of units while file properties use another.
Network speeds vs file sizes
Internet speeds are usually quoted in megabits per second (Mb/s), while file sizes are in megabytes (MB). 1 byte = 8 bits, so a 100 Mb/s link transfers at most about 12.5 MB/s — explaining why downloads are slower than the headline speed suggests.
Frequently asked questions
Is a "KB" 1,000 or 1,024 bytes?
Both are in use. Storage manufacturers and most standards bodies use 1,000. Operating systems typically display 1,024 (technically a KiB) but label it as KB. This tool supports both.
What is a kibibyte?
The IEC name for the binary (1,024-byte) unit, abbreviated KiB. The intent is to distinguish it cleanly from the decimal kilobyte (1,000 bytes).
Why are network speeds in bits and storage in bytes?
Historical: networking measures the actual signal rate (bits on the wire), while storage measures addressable bytes. Multiply network speed in megabits by 0.125 to get megabytes per second.