Data Size Converter
Convert digital storage between bits and bytes, decimal KB/MB/GB/TB and binary KiB/MiB/GiB/TiB — and see why they differ.
How it works
bits = value × factor(from) · result = bits ÷ factor(to) (1 byte = 8 bits · 1 MB = 10⁶ B · 1 MiB = 2²⁰ B)
All sizes convert through the bit, with one byte equal to 8 bits. The catch is that "kilo/mega/giga" have two meanings: the decimal SI prefixes (KB, MB, GB) are powers of 1000, while the binary prefixes (KiB, MiB, GiB) are powers of 1024. Storage vendors label drives in decimal GB, but operating systems often report binary GiB, which is why a "1 TB" drive shows as about 931 GiB.
Worked example
Convert 1 GB to MB: 1 × 8×10⁹ = 8×10⁹ bits, then ÷ 8×10⁶ = 1000 MB. But 1 GiB = 8×2³⁰ bits ÷ 8×10⁶ = 1073.74 MB, showing the decimal-versus-binary gap.
Sources: Binary prefix — Wikipedia
Frequently asked questions
Why does my 1 TB drive show as 931 GB?
The drive is 1 TB in decimal terms (10¹² bytes), but your operating system reports in binary gibibytes (2³⁰ bytes) while still labelling them "GB". 10¹² ÷ 2³⁰ ≈ 931, so the capacity looks smaller even though nothing is missing.
What is the difference between MB and MiB?
A megabyte (MB) is 1,000,000 bytes; a mebibyte (MiB) is 1,048,576 bytes (2²⁰). MiB is about 4.9% larger. The binary units (KiB, MiB, GiB) were introduced to end the ambiguity.
How many bits are in a byte?
Eight. A byte is 8 bits, enough to represent 256 distinct values (2⁸). Network speeds are usually quoted in bits per second, while file sizes are in bytes, so an 8× factor separates them.
Related calculators
This calculator is for educational purposes. Double-check important results before acting on them.