Mebibyte to Kibibyte
MiB
KiB
Conversion History
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|---|---|---|
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Quick Reference Table (Mebibyte to Kibibyte)
| Mebibyte (MiB) | Kibibyte (KiB) |
|---|---|
| 1 | 1,024 |
| 4 | 4,096 |
| 8 | 8,192 |
| 16 | 16,384 |
| 32 | 32,768 |
| 64 | 65,536 |
| 128 | 131,072 |
About Mebibyte (MiB)
A mebibyte (MiB) equals exactly 1,048,576 bytes (2²⁰ bytes) in the IEC binary system. It is 4.86% larger than the decimal megabyte (1,000,000 bytes). The mebibyte is the standard unit for RAM display in Linux and many Unix-like systems, CD-ROM data capacity (a 74-minute CD holds 650 MiB), floppy disk capacities, and kernel and firmware image sizes. When a Linux system reports "free: 512 MiB", it means exactly 536,870,912 bytes — a precise binary figure aligned with hardware allocation. The mebibyte is broadly adopted in technical documentation.
A standard CD-ROM holds 650 MiB (681,574,400 bytes). Linux kernel images are typically 8–12 MiB. A standard 3.5-inch floppy disk held 1.44 MiB.
About Kibibyte (KiB)
A kibibyte (KiB) equals exactly 1,024 bytes (2¹⁰ bytes) in the IEC binary system. It is the binary equivalent of the kilobyte, introduced by the IEC in 1998 to end the ambiguity of using "kilobyte" to mean both 1,000 and 1,024 bytes. The kibibyte is 2.4% larger than the decimal kilobyte (1,000 bytes). Modern operating systems and file managers increasingly use KiB for file sizes; Linux tools (ls, df, free) display binary KiB by default. It is the natural unit for memory addressing, where hardware is organized in 1,024-byte blocks.
A standard floppy disk sector was 512 bytes; two sectors = 1 KiB. Linux displays a 1,024-byte file as "1.0K" by default, meaning 1 KiB.
Mebibyte – Frequently Asked Questions
What is the difference between MB and MiB?
MB (megabyte) = 1,000,000 bytes (SI decimal). MiB (mebibyte) = 1,048,576 bytes (IEC binary). MiB is 4.86% larger. This gap is why a file manager on Linux showing "512 MiB" of free RAM and a marketing sheet showing "512 MB" of RAM are technically different: the marketing sheet refers to fewer bytes.
Why is a CD 650 MB or 650 MiB?
The original CD-ROM standard defined capacity as 74 minutes of audio or 650,000,000 bytes. Technically this is 650 MB in SI terms, or approximately 620 MiB (since 650,000,000 ÷ 1,048,576 ≈ 620). However, the CD industry loosely used "MB" to mean 650 × 10⁶ bytes. Some media used 700 MB (≈ 668 MiB). This inconsistency is a classic example of the pre-IEC ambiguity.
Why are Docker and container image sizes often confusing in MiB vs MB?
Docker reports image sizes in decimal MB (e.g., "docker images" shows 150 MB), but the underlying layer storage on disk uses binary-aligned block sizes. A "150 MB" Docker image actually occupies roughly 143 MiB on disk before compression. Compressed layers further complicate things: a 150 MB uncompressed image might only transfer 50 MB over the network. Container registries like Docker Hub display compressed sizes, while "docker images" shows uncompressed — leading to frequent confusion in CI/CD pipeline size budgets.
How big is a mebibyte in practical terms?
One mebibyte (1,048,576 bytes) holds about: one minute of MP3 audio at 128 kbps (≈ 960 kB, so slightly under 1 MiB), a medium-resolution JPEG photo (0.5–2 MiB), about 200 pages of plain text, or the complete text of a short novel. A typical Linux kernel image at boot is 8–12 MiB compressed.
Why do RAM sticks come in powers of 2 (4, 8, 16 GiB) but USB drives don't?
RAM chips are physically organized as binary address grids — each address line doubles the capacity, so sizes must be exact powers of 2 (4 GiB = 2³² bytes, 8 GiB = 2³³ bytes). USB flash drives use NAND flash that is also binary internally, but manufacturers reserve variable amounts for wear levelling, bad block management, and controller firmware. A "64 GB" USB drive might have 64 GiB of raw NAND but only expose 59.6 GiB (64 × 10⁹ ÷ 2³⁰) to the user — the label uses decimal marketing, unlike RAM which honestly reflects binary sizing.
Kibibyte – Frequently Asked Questions
What is the difference between KB and KiB?
KB (kilobyte, SI) = 1,000 bytes. KiB (kibibyte, IEC binary) = 1,024 bytes. The difference is 24 bytes (2.4%) — small individually but the source of the well-known discrepancy between storage manufacturer labels and OS-reported sizes. Storage manufacturers use KB = 1,000 bytes; operating systems traditionally used KB = 1,024 bytes (now correctly called KiB).
Why does Linux use KiB by default?
Linux memory management, filesystem block sizes, and page sizes are all powers of 2 (typically 4,096 bytes = 4 KiB). Using kibibytes aligns with the physical hardware structure. The GNU coreutils (df, du, ls -h) display sizes in KiB, MiB, GiB by default for consistency with how the kernel allocates memory and disk blocks — decimal kilobytes would produce fractional values for normal aligned allocations.
How do programming languages handle KiB vs KB internally?
Most languages expose both conventions depending on the API. Java's Runtime.totalMemory() returns bytes aligned to KiB (binary), but Files.size() returns raw byte counts that file managers may display as decimal KB. Python's os.path.getsize() returns bytes — the developer chooses how to format. Go's humanize library defaults to IEC (KiB) while many JavaScript libraries default to SI (KB). This inconsistency means the same file can appear as different sizes across tools written in different languages.
What is a page in memory management and how does KiB relate?
A memory page is the smallest unit of memory the OS allocates from physical RAM. Most modern CPUs use 4 KiB (4,096 byte) pages; some support 2 MiB or 1 GiB "huge pages" for performance. Every memory allocation is rounded up to the nearest page boundary. This binary alignment is why computer memory sizes are always powers of 2 (4 GB, 8 GB, 16 GB RAM) rather than round decimal numbers (5 GB, 10 GB).
Why was the "1.44 MB" floppy disk not actually 1.44 MB or 1.44 MiB?
The 3.5-inch floppy's capacity was 1,474,560 bytes — which is neither 1.44 MB (1,440,000 bytes) nor 1.44 MiB (1,509,949 bytes). The label came from a hybrid calculation: 80 tracks × 2 sides × 18 sectors × 512 bytes = 1,474,560 bytes, then divided by 1,000 to get 1,474.56 KB, then divided by 1,024 to get "1.44 MB." This mix of decimal and binary division in the same label is one of the most famous unit blunders in computing history.