Convert data size between bits, bytes and decimal units (KB, MB, GB, TB, powers of 1000) or binary units (KiB, MiB, GiB, TiB, powers of 1024). Free, in your browser.
Decimal vs binary data units
There are two competing systems for data sizes, and mixing them up is the classic source of 'missing' disk space. Decimal (SI) units go up in powers of 1,000: 1 KB = 1,000 bytes, 1 GB = 10⁹ bytes — this is what drive manufacturers and network speeds use. Binary (IEC) units go up in powers of 1,024: 1 KiB = 1,024 bytes, 1 GiB = 2³⁰ = 1,073,741,824 bytes — this is what operating systems and RAM sizes typically use, sometimes while confusingly printing 'GB'. The gap compounds with each step: a '1 TB' drive holds 10¹² bytes, which is only about 931 GiB. All conversions here go through the byte, and a byte is 8 bits.
1 GB = 10⁹ B · 1 GiB = 2³⁰ B = 1,073,741,824 B · 1 B = 8 bitsFrequently asked questions
Is anything I enter uploaded anywhere?
No. The conversion runs locally in your browser — nothing you enter is sent to a server, logged or stored. Only the value and selected units appear in the URL so you can share the exact conversion.
Why does my 1 TB drive show only about 931 GB?
The drive really holds 1 TB = 10¹² bytes, but many operating systems report sizes in binary units — 10¹² ÷ 2³⁰ ≈ 931 GiB — while labelling them 'GB'. Nothing is missing; the two sides are simply using different definitions of the same prefix.
What's the difference between a KB and a KiB?
1 KB (kilobyte) is 1,000 bytes under the SI standard; 1 KiB (kibibyte) is 1,024 bytes under the IEC binary standard. The difference is only 2.4% at kilo scale but grows to 4.9% at mega, 7.4% at giga and 10% at tera — which is why the distinction matters most for large drives.
Last updated: 8 July 2026
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