What is the difference between GiB and GB?

A gibibyte (GiB) = 2^30 = 1,073,741,824 bytes. A gigabyte (GB) uses the SI decimal standard where 1 GB = 1,000,000,000 bytes. The IEC introduced GiB in 1998 to remove ambiguity. Windows reports disk sizes in GiB but labels them "GB," which is why a 1 TB drive appears as ~931 GB in the OS.

What is the difference between MB and MiB?

A megabyte (MB) = 1,000,000 bytes (decimal, SI standard). A mebibyte (MiB) = 1,048,576 bytes (binary, IEC standard). The 4.8% difference grows larger at higher unit sizes and is the main source of confusion when comparing storage values across tools.

How many MB are in 1 GiB?

1 GiB = 1,073,741,824 bytes. Divided by 1,000,000 = 1,073.741824 MB (decimal). As MiB it equals 1,024 MiB (binary). The MB result is the one disk manufacturers and most networking tools use.

Why does my OS show fewer GB than advertised on the drive?

Drive manufacturers use decimal GB (1 GB = 10^9 bytes), while Windows uses binary GiB (2^30 bytes) but calls them "GB." A 1 TB drive (1,000,000,000,000 bytes) becomes ~931.32 GiB when divided by 2^40, so Windows displays ~931 GB.

Can I use this for RAM sizes?

Yes. RAM is always specified and measured in binary units (GiB, MiB). This tool converts those binary GiB values to both decimal MB and binary MiB, useful when comparing specs across datasheets.

Gibibytes to Megabytes Converter

Name: Gibibytes to Megabytes Converter
Availability: InStock
Author: Nham Vu

Convert gibibytes (GiB) to megabytes (MB) or mebibytes (MiB), or reverse — with side-by-side decimal and binary results.

Input Value

Amount

Convert from

Quick presets

Results

Enter a value and click Convert to see results.

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Summary

Convert gibibytes (GiB) to megabytes (MB) or mebibytes (MiB), or reverse — with side-by-side decimal and binary results.

How it works

Enter a value in gibibytes (GiB) or switch the direction to start from megabytes or mebibytes.
The converter multiplies GiB by 1,073,741,824 to get the raw byte count.
It divides bytes by 1,000,000 to get the SI decimal megabyte (MB) result.
It also divides bytes by 1,048,576 to get the binary mebibyte (MiB) result.
Use the Swap button to convert in the opposite direction.
Copy any individual result with the copy button next to it.

Use cases

Understand why a 2 GiB RAM module shows a different value in Windows versus a spec sheet.
Convert file sizes reported by Linux utilities (GiB) to MB for reporting.
Verify storage allocation when provisioning cloud volumes.
Compare OS-reported disk usage (binary GiB) with manufacturer specs (decimal GB).
Calculate video file sizes when tools report in GiB but encoding targets are in MB.
Cross-check backup sizes across tools that use different unit conventions.

Frequently Asked Questions

Last updated: 2026-07-22 · Reviewed by Nham Vu