4KB

4 KB is a unit of digital information equal to 4,096 bytes. In precise terms, it is 4 KiB, since 1 KiB equals 1,024 bytes; the term “KB” is often used interchangeably in non-technical contexts but can denote 1,000 or 1,024 bytes depending on convention.

Most modern computer systems use 4 KiB as the standard page size for virtual memory. A memory page is the smallest unit of data that the operating system can manage for virtual memory, and addresses are translated to physical frames in increments of 4 KiB. Larger page sizes, known as huge or large pages (such as 2 MiB or 1 GiB), exist to reduce page-table overhead for certain workloads.

In storage, many filesystems use 4 KiB as the fundamental block or cluster size. Examples include ext4, NTFS, and XFS defaults, though block sizes can vary by filesystem and configuration. I/O operations are often aligned to 4 KiB boundaries to improve throughput and reduce fragmentation. Disk drives historically used 512-byte sectors; many modern drives support 4 KiB sectors (advanced format) for improved efficiency and error correction.

Calculation notes: 1 page equals 4,096 bytes; 256 pages total 1,048,576 bytes, i.e., 1 MiB. The 4 KiB size is a balance between granularity for small data and overhead for managing many memory blocks; it remains a common default across architectures, though some systems employ larger page sizes for specific performance goals.