データストレージユニットコンバーター（ビット、バイト、KB、MB、GB、TB）
ガイド
Data Storage Unit Converter
Convert between data storage units instantly with both SI (decimal) and IEC (binary) systems displayed side by side. Enter a value in bits, bytes, kilobytes, megabytes, gigabytes, terabytes, or any other unit and see all equivalents update in real time. Correctly distinguishes between KB (1000 bytes) and KiB (1024 bytes) — a difference that causes constant confusion in computing. Includes quick-select buttons for common storage sizes and a reference table.
使い方
Enter a storage value in any supported unit and all other units update simultaneously. The converter shows SI units (KB, MB, GB using powers of 1000) and IEC units (KiB, MiB, GiB using powers of 1024) in separate columns so you can see both systems at a glance. Use quick-select buttons to load common storage sizes like a floppy disk, CD, DVD, or SSD. Adjust decimal precision and copy individual values or all conversions.
特徴
- SI and IEC Side by Side – See both decimal (KB/MB/GB/TB/PB/EB) and binary (KiB/MiB/GiB/TiB/PiB/EiB) conversions simultaneously
- 15+ Units – Bit, nibble, byte, plus all SI prefixes (kilo through exa) and all IEC prefixes (kibi through exbi)
- Quick-Select Buttons – One-click common sizes: floppy disk, CD, DVD, Blu-ray, typical SSD and HDD capacities
- Comma-Formatted Output – Large numbers displayed with comma separators for readability
- 参考表 – Common storage media with their capacities in both SI and IEC units
- Configurable Precision – Set decimal places from 0 to 10
- Copy Values – Copy individual conversions or all results at once
よくある質問
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What is the difference between KB and KiB?
KB (kilobyte) uses the SI decimal definition where 1 KB = 1000 bytes. KiB (kibibyte) uses the IEC binary definition where 1 KiB = 1024 bytes. This distinction matters because operating systems, hard drive manufacturers, and software use different conventions. A drive advertised as 1 TB (1,000,000,000,000 bytes) shows as roughly 931 GiB in most operating systems that use binary counting. The IEC prefixes (kibi, mebi, gibi) were introduced in 1998 to eliminate this ambiguity.
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Why does my hard drive show less space than advertised?
Hard drive manufacturers use SI units where 1 TB = 1,000,000,000,000 bytes (powers of 1000). However, most operating systems report storage using binary units where 1 TiB = 1,099,511,627,776 bytes (powers of 1024). A 1 TB drive contains exactly the advertised number of bytes, but the OS displays it as approximately 931 GiB. The larger the drive, the bigger the apparent discrepancy. A 2 TB drive shows as about 1.82 TiB.
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How many bits are in a byte?
One byte contains exactly 8 bits. A bit (binary digit) is the smallest unit of data, representing a single 0 or 1. A nibble is 4 bits (half a byte). These relationships are fixed and universal in modern computing. All larger storage units (kilobytes, megabytes, etc.) are defined as multiples of bytes, with the multiplier depending on whether you use SI (powers of 1000) or IEC (powers of 1024) conventions.
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When should I use SI units versus IEC units?
Use SI units (KB, MB, GB) when discussing network speeds, hard drive capacities as marketed, and data transfer rates, since these industries consistently use powers of 1000. Use IEC units (KiB, MiB, GiB) when discussing RAM capacity, file sizes as reported by operating systems, and any context where binary precision matters. In programming, IEC units are more accurate since memory is allocated in powers of 2.
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