How many bytes are in a kilobyte?

In the SI decimal standard (used by storage manufacturers and most networking tools), 1 kilobyte (KB) = 1,000 bytes. In the IEC binary standard (used by most operating systems), 1 kibibyte (KiB) = 1,024 bytes. The two standards give slightly different byte counts for the same KB value.

Why does my OS report more bytes than the vendor KB spec?

Storage vendors advertise capacity using SI (1 KB = 1,000 bytes), while Windows and many operating systems calculate using binary (1 KiB = 1,024 bytes) but often still label the result "KB". A file described as 1 KB by a vendor is 1,000 bytes; the same file in OS binary terms is just under 1 KiB (0.977 KiB).

Which definition should I use?

Use SI (1 KB = 1,000 bytes) when working with storage specs, network throughput, and most developer APIs. Use binary (1 KiB = 1,024 bytes) when interpreting values reported by operating systems or doing low-level binary arithmetic.

What is a kibibyte (KiB)?

Kibibyte is the IEC 80000-13 standard term for exactly 1,024 bytes. It was introduced to remove the ambiguity of "kilobyte," which historically referred to both 1,000 and 1,024 bytes depending on context.

Can I convert larger units here?

This tool focuses on the kilobyte-to-byte step. For larger conversions (KB to MB, MB to GB, etc.) use the related tools linked below.

Kilobytes to Bytes Converter

Name: Kilobytes to Bytes Converter
Availability: InStock
Author: Nham Vu

Enter a kilobyte value and instantly get bytes using SI decimal (1 KB = 1,000 B) and binary IEC (1 KiB = 1,024 B), plus a quick-reference table.

Enter Kilobytes

Kilobytes (KB)

SI vs Binary: KB (kilobyte) = 1,000 bytes — used by storage manufacturers and networking. KiB (kibibyte) = 1,024 bytes — used by operating systems.

Result

Enter a kilobyte value to see the conversion.

Quick-Reference Table

Kilobytes (KB)	Bytes SI (× 1,000)	Bytes Binary (× 1,024)
0.5 KB	500 B	512 B
1 KB	1,000 B	1,024 B
4 KB	4,000 B	4,096 B
10 KB	10,000 B	10,240 B
64 KB	64,000 B	65,536 B
100 KB	100,000 B	102,400 B
512 KB	512,000 B	524,288 B
1,000 KB	1,000,000 B	1,024,000 B

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Summary

Enter a kilobyte value and instantly get bytes using SI decimal (1 KB = 1,000 B) and binary IEC (1 KiB = 1,024 B), plus a quick-reference table.

How it works

Enter any number of kilobytes in the input field.
The converter multiplies the KB count by 1,000 to get bytes (SI decimal).
It also multiplies by 1,024 to show what 1 KiB equals in bytes (IEC binary) as a secondary reference.
Results update instantly as you type.
The quick-reference table shows common KB values converted to both B (decimal) and B (binary).
Use the copy button next to each result to copy the value to your clipboard.

Use cases

Verify raw byte counts for packets or payloads expressed in KB.
Compare a storage spec listed in KB against actual bytes stored on disk.
Convert KB file size limits from upload restrictions into exact byte thresholds.
Cross-check API rate limits or buffer sizes that mix KB and byte units.
Calculate exact byte allocation for fixed-size memory blocks given in KB.
Understand why an OS shows a slightly different byte count than a vendor KB spec.

Frequently Asked Questions

Last updated: 2026-07-23 · Reviewed by Nham Vu