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Convert Bytes to Kilobytes - Data Storage Converter

Quickly convert values expressed in bytes to kilobytes. This tool gives a precise numeric conversion and explains the two common conventions you may encounter when interpreting results.

There are two widely used definitions: the SI (decimal) kilobyte where 1 KB = 1,000 bytes, and the binary-derived kibibyte where 1 KiB = 1,024 bytes. The decimal definition is used by most storage manufacturers and SI standards; the binary definition is common in operating system displays and low-level computing contexts.

Updated Nov 28, 2025

Interactive Converter

Convert between byte and kilobyte with precision rounding.

Quick reference table

ByteKilobyte
1 B0 KB
5 B0.01 KB
10 B0.01 KB
25 B0.03 KB
50 B0.05 KB
100 B0.1 KB

Methodology

This converter performs a straightforward unit conversion using fixed numeric relationships. For clarity we present both conventions and the circumstances in which each is appropriate.

Standards bodies and federal laboratories define prefixes: the SI prefix kilo (k) equals 1,000 (see NIST SI prefixes), while international standards introduced binary prefixes (kibi, mebi) to denote powers of two (1 KiB = 1,024 bytes). When converting, pick the convention that matches your source: decimal (manufacturer marketing, SI) or binary (OS reports, memory addressing).

Results are computed with standard IEEE double-precision arithmetic for reliability on a broad range of inputs. Display rounding is configurable in the product UI; carry out large-scale or audit-grade conversions with exact integer arithmetic if you need bit-perfect accounting.

Worked examples

Example 1 (decimal): 5,000 bytes ÷ 1,000 = 5 KB

Example 2 (binary): 5,120 bytes ÷ 1,024 = 5 KiB (often displayed as 5 KB by operating systems)

Further resources

Expert Q&A

Which definition should I use: 1,000 or 1,024?

Use 1,000 (decimal) when matching manufacturer specs, storage device capacities, or SI-compliant reporting. Use 1,024 (binary) when working with low-level memory addressing, legacy software that reports in powers of two, or when your operating system explicitly describes sizes in binary units. Check the source of the byte value to pick the correct convention.

Why does my hard drive show a smaller capacity in my computer than on the box?

Manufacturers typically advertise capacities using decimal kilobytes (1 KB = 1,000 bytes). Many operating systems report sizes using binary-based units (1 KiB = 1,024 bytes) or historically label them as KB. The differing base (1000 vs 1024) explains the apparent discrepancy.

Is this converter exact for very large numbers?

The conversion is mathematically exact as an integer relationship (divide or multiply by 1,000 or 1,024). For presentation we use standard floating-point formatting; if you need exact integer results for extremely large values, use integer arithmetic or export the raw integer output to downstream tooling to avoid any display rounding.

Do standards bodies prescribe one definition over the other?

SI and NIST prescribe SI prefixes where kilo = 1,000. International electrotechnical standards introduced binary prefixes (kibi, mebi) to represent powers of two explicitly. Use the prefix that best matches your reporting or technical requirement and cite the appropriate standard as needed.

How should I report sizes in documentation or regulated filings?

Prefer unambiguous notation: give the numeric value and the unit (for example, “5,000 bytes (4.88 KB decimal)” or “5,120 bytes (5 KiB)”), and state which convention you used. Where applicable follow organizational or regulatory guidance and cite standards such as NIST or relevant ISO/IEC documents.

Can I convert back and forth between KB and KiB here?

Yes. Convert bytes to decimal kilobytes by dividing by 1,000, or to binary kibibytes by dividing by 1,024. To switch between KB (decimal) and KiB (binary), convert to bytes first then use the other divisor to avoid compounding rounding error.

Sources & citations