Data Storage Converter
Convert data storage sizes between bytes, KB, MB, GB, TB, and PB. Uses both decimal (1 KB = 1,000 bytes) and binary (1 KiB = 1,024 bytes) standards.
Reviewed by Richard Ross · Last updated April 2026
How Data Storage Converter works
Decimal (SI) vs binary (IEC) units
Storage manufacturers use decimal units: 1 KB = 1,000 bytes; 1 MB = 1,000,000 bytes. Operating systems traditionally used binary: 1 KiB = 1,024 bytes. This causes the familiar discrepancy: a "1 TB" hard drive appears as ~931 GB in Windows.
IEC standard
To remove ambiguity, the IEC introduced the kibibyte (KiB), mebibyte (MiB), gibibyte (GiB), and tebibyte (TiB) for binary units. Modern operating systems (macOS, Linux) now use decimal GB consistently; Windows still uses binary GiB but labels them as GB.
Real-world file and device sizes
Understanding storage sizes helps you plan capacity. A typical MP3 song is 3–5 MB; a high-quality FLAC file is 20–40 MB. A 1080p HD film is roughly 4–8 GB; a 4K Blu-ray rip can be 50–80 GB. A smartphone camera photo (12 MP) is approximately 3–6 MB. A standard UK broadband plan might include a 1 TB monthly data cap — equivalent to streaming around 500 hours of HD video.
Broadband speed vs storage size
Broadband speeds are measured in megabits per second (Mbps), not megabytes. There are 8 bits in a byte. A 100 Mbps broadband connection can theoretically download at 12.5 MB/s. Downloading a 1 GB file at 100 Mbps takes approximately 80 seconds. UK average broadband speeds rose to around 80 Mbps in 2024; full fibre (FTTP) connections commonly offer 900 Mbps.
Common mistakes and clarifications
The KB/KiB confusion is one of the most common sources of misunderstanding in consumer technology. When a phone manufacturer advertises 256 GB of storage, this is decimal — the device will show approximately 238 GiB available. Similarly, a 2 TB external hard drive contains 2,000 GB (decimal) but appears as roughly 1.82 TiB in binary-calculating systems. Always check whether a spec sheet uses decimal or binary when comparing storage products.
Frequently asked questions
Why does my 1 TB drive show as 931 GB?
Drive manufacturers use 1 TB = 1,000,000,000,000 bytes. Windows divides by 1,073,741,824 (1024³) to get GiB, but labels the result as GB. 1,000,000,000,000 ÷ 1,073,741,824 = 931.3 GiB.
How many GB in a TB?
1 TB (decimal) = 1,000 GB. 1 TiB (binary) = 1,024 GiB.
How many MB in a GB?
1 GB (decimal) = 1,000 MB. 1 GiB (binary) = 1,024 MiB.
What is a gigabyte?
A gigabyte (GB) in the decimal system is 1,000,000,000 bytes (10⁹). In the binary system, a gibibyte (GiB) is 1,073,741,824 bytes (2³⁰).
How many GB is a typical film download?
A standard-definition film is roughly 700 MB–1.5 GB. An HD (1080p) film is typically 4–8 GB. A 4K HDR film can be 15–80 GB depending on compression. Streaming services use lower bitrates — Netflix HD uses around 3 GB per hour.
What is the difference between Mbps and MB/s?
Mbps (megabits per second) measures network/broadband speed. MB/s (megabytes per second) measures file transfer speed. Since 1 byte = 8 bits, divide Mbps by 8 to get MB/s. A 100 Mbps connection transfers approximately 12.5 MB/s.
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