Block to Kibibyte
blk
KiB
Conversion History
| Conversion | Reuse | Delete |
|---|---|---|
| No conversion history to show. | ||
Quick Reference Table (Block to Kibibyte)
| Block (blk) | Kibibyte (KiB) |
|---|---|
| 512 | 0.0625 |
| 1,024 | 0.125 |
| 2,048 | 0.25 |
| 4,096 | 0.5 |
| 8,192 | 1 |
| 65,536 | 8 |
About Block (blk)
A block (also called a disk block or storage block) is a fixed-size unit of data used by filesystems and storage devices when reading or writing to disk. Block size is not fixed across systems — common sizes are 512 bytes (the historic disk sector size), 4,096 bytes (4 KiB, the modern standard for HDDs and SSDs), and larger sizes (64 KiB, 1 MiB) for enterprise storage arrays. Filesystems allocate space in whole blocks: a 1-byte file still consumes one full block on disk. Block size affects performance (larger blocks favor sequential reads) and space efficiency (smaller blocks waste less space on small files).
A 4,096-byte (4 KiB) block filesystem storing a 1-byte text file uses 4,096 bytes of disk space — 4,095 bytes are wasted. On a system with 1 million tiny files, this slack space becomes significant.
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.
Block – Frequently Asked Questions
What is the default block size for modern hard drives and SSDs?
Modern hard drives (2011+) and SSDs use 4,096-byte (4 KiB) physical sectors — known as "Advanced Format" or AF. Legacy drives used 512-byte sectors. Filesystems (NTFS, ext4, APFS) typically use 4 KiB logical block sizes to match physical sectors, which avoids the performance penalty of misaligned writes. Enterprise SSDs may use larger block sizes (16 KiB or more) for better parallelism.
What is block size in cloud storage?
Cloud block storage services (AWS EBS, Azure Managed Disks, GCP Persistent Disk) use I/O block sizes typically of 4 KiB or 16 KiB. Performance is measured in IOPS (I/O operations per second) and throughput (MB/s) — both depend on block size. A throughput-optimized workload (sequential video) benefits from large blocks; an IOPS-optimized workload (database random reads) uses small blocks.
Why does a tiny file take up so much disk space?
Filesystems allocate disk space in whole blocks. On a system with 4 KiB blocks, every file — no matter how small — occupies at least 4,096 bytes. A directory of 10,000 small configuration files (each 100 bytes of content) uses 40 MB of disk space (10,000 × 4,096 bytes) rather than 1 MB (10,000 × 100 bytes). This is called "block slack" or "internal fragmentation".
What is the difference between a disk block and a database block?
Disk blocks (filesystem blocks) are typically 512 bytes to 4 KiB. Database blocks (database pages) are the unit of I/O for a database engine — typically 8 KiB (PostgreSQL, SQL Server), 16 KiB (MySQL InnoDB), or 32 KiB (Oracle, configurable). Database blocks usually align to multiples of disk blocks for efficiency. Reading one database page may involve reading 2–8 disk blocks.
What is RAID stripe size and how does it relate to block size?
RAID stripe size (or chunk size) is the amount of data written to each drive before moving to the next drive in the array — typically 64 KiB to 512 KiB. It should be set to match your workload: sequential large-file workloads benefit from larger stripe sizes; random small-block workloads benefit from stripe sizes closer to the filesystem block size. Mismatched stripe and block sizes cause write amplification and reduce RAID performance.
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.