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.
Governance
Record 77355199d5e7 • Reviewed by Fidamen Standards Committee
Interactive Converter
Convert between gigabyte and megabyte with precision rounding.
Quick reference table
| Gigabyte | Megabyte |
|---|---|
| 1 GB | 125 MB |
| 5 GB | 625 MB |
| 10 GB | 1,250 MB |
| 25 GB | 3,125 MB |
| 50 GB | 6,250 MB |
| 100 GB | 12,500 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.
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.
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.
F.A.Q.
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
- NIST reference on SI prefixes and units — https://physics.nist.gov/cuu/Units/prefixes.html
- ISO/IEC standards for quantities and units (including binary prefixes) — https://www.iso.org/standard/35480.html
- MIT OpenCourseWare — computing fundamentals and data representation (educational resource) — https://ocw.mit.edu
- IEC 80000-13:2008 — Information science and technology — https://www.iso.org/standard/31898.html
- NIST SP 811 — Guide for the Use of the International System of Units — https://www.nist.gov/pml/special-publication-811
Further resources
Versioning & Change Control
Audit record (versions, QA runs, reviewer sign-off, and evidence).
Record ID: 77355199d5e7What changed (latest)
v1.0.0 • 2025-11-17 • MINOR
Initial publication and governance baseline.
Why: Published with reviewed formulas, unit definitions, and UX controls.
Public QA status
PASS — golden 25 + edge 120
Last run: 2026-01-23 • Run: golden-edge-2026-01-23
Versioning & Change Control
Audit record (versions, QA runs, reviewer sign-off, and evidence).
What changed (latest)
v1.0.0 • 2025-11-17 • MINOR
Initial publication and governance baseline.
Why: Published with reviewed formulas, unit definitions, and UX controls.
Public QA status
PASS — golden 25 + edge 120
Last run: 2026-01-23 • Run: golden-edge-2026-01-23
Engine
v1.0.0
Data
Baseline (no external datasets)
Content
v1.0.0
UI
v1.0.0
Governance
Last updated: Nov 17, 2025
Reviewed by: Fidamen Standards Committee (Review board)
Credentials: Internal QA
Risk level: low
Reviewer profile (entity)
Fidamen Standards Committee
Review board
Internal QA
Entity ID: https://fidamen.com/reviewers/fidamen-standards-committee#person
Semantic versioning
- MAJOR: Calculation outputs can change for the same inputs (formula, rounding policy, assumptions).
- MINOR: New features or fields that do not change existing outputs for the same inputs.
- PATCH: Bug fixes, copy edits, or accessibility changes that do not change intended outputs except for previously incorrect cases.
Review protocol
- Verify formulas and unit definitions against primary standards or datasets.
- Run golden-case regression suite and edge-case suite.
- Record reviewer sign-off with credentials and scope.
- Document assumptions, limitations, and jurisdiction applicability.
Assumptions & limitations
- Uses exact unit definitions from the Fidamen conversion library.
- Internal calculations use double precision; display rounding follows the unit's configured decimal places.
- Not a substitute for calibrated instruments in regulated contexts.
- Jurisdiction-specific rules may require official guidance.
Change log
v1.0.0 • 2025-11-17 • MINOR
Initial publication and governance baseline.
Why: Published with reviewed formulas, unit definitions, and UX controls.
Areas: engine, content, ui • Reviewer: Fidamen Standards Committee • Entry ID: 874ab82ee577