What is the difference between GB and GiB?

GB (gigabyte) uses the SI standard: 1 GB = 1,000,000,000 bytes. GiB (gibibyte) uses the IEC binary standard: 1 GiB = 1,073,741,824 bytes (2^30). Hard drive manufacturers use GB; operating systems like Windows and Linux often report sizes in GiB.

Why does my 1 TB hard drive show less space in Windows?

Drive makers measure 1 TB as 1,000,000,000,000 bytes (SI). Windows reports capacity in GiB but labels it GB, so 1 TB appears as about 931 GiB.

A petabyte (PB) is 1,000 terabytes in SI, or about 1 quadrillion bytes. A pebibyte (PiB) is 2^50 bytes = 1,125,899,906,842,624 bytes.

Which standard should I use?

Use SI (KB, MB, GB) when matching storage device specs or network transfer rates. Use IEC (KiB, MiB, GiB) when matching what most operating systems actually report.

Can I enter decimal values?

Yes. Any decimal number is accepted in any field.

Data Storage Converter

Enter any storage value and instantly see it in all units for both SI (1 KB = 1000 B) and binary IEC (1 KiB = 1024 B) standards.

Enter a value

Type in any field; all units update instantly.

Bit (b)

Byte (B)

Kilobyte (KB)

Megabyte (MB)

Gigabyte (GB)

Terabyte (TB)

Petabyte (PB)

Conversion Results

SI (1 K = 1,000) IEC (1 Ki = 1,024)

Enter a value on the left to see results.

Supports bits, bytes, KB through PB

Unit	SI value powers of 1,000	IEC value powers of 1,024

Summary

Convert data storage sizes between bytes, KB, MB, GB, TB, and PB using both the SI decimal standard (powers of 1000) and the IEC binary standard (powers of 1024). Useful for comparing hard drive specs, OS-reported sizes, and cloud storage quotas.

How it works

Enter a value in any unit field (e.g. type 1 in the GB field).
All other units update instantly in both SI and IEC columns.
Switch the input unit by typing into a different field.
Click "Clear all" to reset the form.

Use cases

Convert file sizes shown by an OS (IEC, base-1024) vs. a hard drive spec (SI, base-1000).
Calculate how many files fit on a storage device.
Understand the difference between GB and GiB when provisioning cloud storage.
Convert network transfer sizes for bandwidth planning.

Frequently Asked Questions

Last updated: 2026-05-23 · Reviewed by Nham Vu