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Convert Gigabytes to Megabytes – Data Converter

This tool converts values from gigabytes (GB) to megabytes (MB). It shows the standard mathematical relationships and explains the difference between decimal (SI) and binary (IEC) interpretations so you can pick the one that matches your context.

Storage manufacturers commonly use the decimal definition (1 GB = 1,000 MB), while many operating systems and technical tools use the binary interpretation (1 GiB = 1,024 MiB). This converter supports the canonical unit mapping (gigabyte → megabyte) and the explanatory material below helps you choose the correct interpretation for reporting, procurement, or technical analysis.

For regulated reporting or technical documentation, we reference standards and guidance from recognized authorities so you can cite the correct convention in audits or specifications.

Updated Nov 17, 2025

Interactive Converter

Convert between gigabyte and megabyte with precision rounding.

Quick reference table

GigabyteMegabyte
1 GB125 MB
5 GB625 MB
10 GB1,250 MB
25 GB3,125 MB
50 GB6,250 MB
100 GB12,500 MB

Methodology

The converter uses fixed unit definitions from the standard conversions library. When you enter a gigabyte value, the library returns the equivalent megabytes using the defined unit mapping.

Two common conventions exist: the decimal (SI) convention uses powers of 10 (1 GB = 1,000 MB) and is favored by storage manufacturers and many specifications; the binary (IEC) convention uses powers of 2 (1 GiB = 1,024 MiB) and is often used in operating systems and low-level software. The library exposes distinct unit IDs for these where needed (e.g., gibibyte, mebibyte) so technical workflows can remain unambiguous.

Rounding and display precision are handled at the presentation layer; for reporting or compliance requirements, present converted values with the precision required by the regulating body or specification.

Worked examples

Example — decimal (manufacturer convention): 1 GB = 1,000 MB. 128 GB = 128,000 MB.

Example — binary (technical/OS convention): 1 GiB = 1,024 MiB. 128 GiB = 131,072 MiB (commonly displayed by some operating systems).

Manual check: To convert 7.2 GB to MB (decimal): 7.2 × 1,000 = 7,200 MB.

Key takeaways

This converter provides a single-step conversion from gigabytes to megabytes using the configured unit definitions. Be explicit about whether you mean decimal (GB → MB, ×1,000) or binary (GiB → MiB, ×1,024) to avoid ambiguity in documentation and reporting.

When in doubt for regulatory or procurement contexts, cite the applicable standards (NIST, ISO/IEC) and state the convention used in your report.

Expert Q&A

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

Use 1,000 (decimal) when you’re following manufacturer datasheets, marketing, or SI-based documentation. Use 1,024 (binary/IEC) when working with low-level software, memory addressing, or when the specification explicitly uses GiB/MiB. For formal standards or regulatory reporting, follow the convention specified by the governing document.

Why does my computer show less capacity than the manufacturer states?

Manufacturers typically quote decimal gigabytes (1 GB = 1,000 MB). Many operating systems report storage using binary units (1 GiB = 1,024 MiB) but label them as 'GB' for historical reasons, which makes the displayed number smaller. Converting between the two conventions explains the discrepancy.

Are GB and GiB interchangeable?

No. GB normally means decimal gigabyte (1,000³ bytes) while GiB (gibibyte) is a binary unit (1,024³ bytes). For technical accuracy, use 'GiB'/'MiB' when you mean binary multiples and 'GB'/'MB' when you mean decimal multiples.

How precise is the conversion?

The mathematical relationships are exact for the defined conventions: multiplication by 1,000 (decimal) or 1,024 (binary). Display precision (number of decimal places) is a UI choice; for audits or specs, round according to the required number of significant digits in your documentation.

Which references define these conventions?

The International Electrotechnical Commission (IEC) defines binary prefixes such as kibibyte, mebibyte, and gibibyte for powers-of-two. SI prefixes and decimal conventions are documented by metric standards authorities. See the citations below for authoritative guidance.

Sources & citations