Data Storage Converters 12
Is a kilobyte 1,000 bytes or 1,024? Both answers are correct — and that's the problem. Hard drive manufacturers use decimal (1,000), operating systems use binary (1,024), and the 1998 IEC tried to fix it with "kibibytes" which nobody adopted. Our converters default to the decimal/SI convention used on product packaging, but every converter page explains both. For data transfer rates (Kbps, Mbps, Gbps), the decimal convention is universal — networking has always used powers of 10.
Read the Data Storage Conversion Guide
Why your 1 TB drive shows 931 GB. The class-action lawsuits, the IEC standard nobody adopted, and why Windows and macOS give different file sizes for the same byte count.
Open the full guide →Data Storage: Why 1 GB Is Not 1,024 MB — And Sometimes It Is
Data storage units suffer from a 66-year-old naming collision between binary addressing (powers of 2) and decimal marketing (powers of 10). Computer memory is inherently binary: RAM is addressed in powers of 2, so 1 kilobyte of RAM = 1,024 bytes (2¹⁰). But hard drive manufacturers have always used decimal: 1 kilobyte = 1,000 bytes (10³). The difference compounds: by the time you reach terabytes, the gap is 9.95% — which is why your "1 TB" hard drive shows only 931 GB in Windows.
The IEC attempted to resolve this in 1998 by introducing binary prefixes: kibibyte (KiB = 1,024 bytes), mebibyte (MiB), gibibyte (GiB), tebibyte (TiB). Almost nobody adopted them. Windows still uses "GB" to mean GiB. macOS switched to decimal GB in 2009. Linux distributions vary. The result: a file that is "100 MB" in macOS might show as "95.4 MB" in Windows — same bytes, different counting.
Data Transfer vs. Storage
1 Mbps = 1,000,000 bits per second (data transfer — always decimal)
1 Gbps = 1,000 Mbps | 1 MB/s = 8 Mbps (bytes vs bits — another trap)
1 kB = 1,000 bytes (SI) or 1,024 bytes (binary) — context matters
The class-action lawsuits over hard drive capacities in the 2000s — Western Digital, Seagate, and others — all settled. The customer lost. For the full story of the binary-decimal war, see the Data Storage Conversion Guide.
The Class-Action Lawsuits: When Hard Drive Marketing Met Consumer Expectations
Between 2003 and 2007, Western Digital, Seagate, and Hitachi faced class-action lawsuits over hard drive capacity labeling. A drive sold as "80 GB" would show approximately 74.5 GB in Windows. The plaintiffs argued deceptive marketing; the manufacturers argued that they were using the correct SI prefix (giga- = 10⁹, so 80 GB = 80,000,000,000 bytes), and that it was Windows reporting in GiB while calling it GB — Microsoft's labeling error, not theirs. Courts agreed with the manufacturers. The cases settled for modest sums (coupons for future purchases, free backup software), and the industry adopted disclaimer labels: "1 GB = 1,000,000,000 bytes. Actual formatted capacity may be less."
The real impact of these lawsuits was regulatory, not financial. The settlements forced hard drive packaging to display the actual byte count and the decimal definition in fine print. But they also cemented the status quo: drive manufacturers continue using decimal, operating systems continue using binary, and the consumer continues seeing a ~7% discrepancy at the gigabyte scale and a ~10% discrepancy at the terabyte scale. The IEC's 1998 kibibyte standard was the correct solution to a real problem; its failure to achieve adoption is a case study in how standards lose to installed base inertia.
Cloud Storage and Data Transfer: Where the Decimal Convention Actually Helps
1 TB cloud storage = 1,000,000,000,000 bytes — cloud providers use decimal TB
1 Gbps fiber = 1,000,000,000 bits per second — networking is always decimal
1 MB/s download = 8 Mbps line rate — plus ~3% overhead (TCP/IP headers)
100 Mbps plan ≈ 11.9 MiB/s actual throughput — decimal-to-binary + protocol overhead
Networking and telecommunications have used decimal prefixes since the invention of the modem — 56 Kbps always meant 56,000 bits per second, not 57,344. This consistency across the entire networking stack is why data transfer conversions are unambiguous: Kbps, Mbps, and Gbps always use powers of 10. The confusion is confined to storage. When your ISP sells you "100 Mbps," they mean 100,000,000 bits per second — roughly 11.9 MiB/s after accounting for TCP/IP overhead and the decimal-to-binary byte conversion. Nobody disputes the networking prefix. The storage industry's decimal convention would be uncontroversial if the memory industry's binary convention had used different words from the start. The failure was in naming, not in mathematics.