Units & Conversion · GB 与 MB（数据单位） · Updated 2026-10-25
What Is GB and MB?
Definition
Data units come in two conventions: decimal (SI, 1 KB=1000 B — drive makers and carriers) and binary (IEC, 1 KiB=1024 B — OS memory). Windows' "GB" is really GiB, so a 1 TB drive shows 931 GB (10^12 ÷ 2^40). Mobile data bills 1 GB = 1000 MB (decimal) while download tools show MB/s often on 1024 — the progress bar and the carrier read differently but nothing is lost.
Formula
1 GiB = 1024 MiB = 2³⁰ B; 1 GB = 1000 MB = 10⁹ B
Worked Example
A 1 TB drive holds 10^12 bytes; Windows shows 10^12/2^40 ≈ 909 GiB as "931 GB" — no shortfall, just convention.
Common Misconception
"Drive makers shortchange me" — decimal is the SI standard; the binary-labeled OS creates the gap. And "300M broadband = 300 MB/s" — bandwidth uses bits: 300 Mbps÷8 = 37.5 MB/s, an 8× gap from storage bytes.
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