What is the difference between KB and KiB?

KB (kilobyte) uses the SI decimal standard where 1 KB = 1000 bytes. KiB (kibibyte) uses the binary standard where 1 KiB = 1024 bytes. The IEC introduced the KiB notation in 1998 to eliminate ambiguity, but many systems still use "KB" to mean 1024 bytes.

Why does my OS show a different file size than the file manager?

Windows uses binary units (1024) but labels them as KB/MB/GB, while macOS uses SI units (1000) for display. This causes the same file to appear different sizes across operating systems.

Which standard should I use?

Use SI (1000) for networking, storage marketing, and data transfer rates. Use binary (1024) when working with RAM, operating system file sizes, or programming contexts where memory addressing is involved.

How accurate is this converter?

Results are computed in JavaScript using 64-bit floating-point arithmetic and displayed to up to 6 decimal places, which is more than sufficient for any practical file size conversion.

Can I convert kilobytes back to bytes?

Yes. Use the Convert from dropdown to choose KB or KiB, then enter a value to get the equivalent byte count.

Bytes to Kilobytes Converter

Convert bytes to kilobytes using SI (1 KB = 1000 B) or binary (1 KiB = 1024 B) standards.

Input Value

Amount

Convert from

Results

Enter a value and click Convert to see results.

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Summary

This tool converts a byte value into kilobytes using both the SI decimal standard (1 KB = 1000 bytes) and the binary standard (1 KiB = 1024 bytes). The SI standard is used by storage manufacturers and networking, while the binary standard (officially kibibytes) is used by operating systems and memory. Seeing both values side by side removes any ambiguity when working with file sizes or data transfer.

How it works

Enter any byte value in the input field.
The converter instantly calculates the SI result: bytes divided by 1000.
It also calculates the binary result: bytes divided by 1024.
Results are displayed to up to 6 decimal places.
Use the copy buttons to grab either value for your work.
Use the Convert from dropdown to enter kilobytes or kibibytes and convert them to bytes.

Use cases

Understand file size differences reported by Windows vs. macOS.
Convert network transfer metrics from bytes to kilobytes.
Clarify storage capacity between drive manufacturers and OS reports.
Quickly check KB values when reading API documentation.
Compare SI and binary byte counts for academic or technical writing.
Validate data payloads during software development and testing.

Frequently Asked Questions

Last updated: 2026-10-05 · Reviewed by Nham Vu