Gigabytes to Megabytes Calculator

Direct answer

Multiply the entered gigabytes value by 1000 to express it in megabytes (MB). This converts gigabyte (GB) to megabyte (MB) within the documented data size family.

Variables and formula

• Gigabytes (GB): the source value measured in gigabyte.
• Megabytes (MB): the same quantity expressed in megabyte.
• Conversion factor: 1000 megabytes per gigabyte.

Megabytes = Gigabytes × 1000

The generator emits numeric factors with at most 15 significant digits. Calculator results keep up to 10 significant digits for display; this formatting does not increase the precision of the measurement.

Unit definitions and named variants

Source unit: gigabyte (GB). A gigabyte uses the decimal SI prefix giga: 1 GB = 1000000000 B exactly. Named variant used: Decimal gigabyte; not gibibyte. Reference: Bureau International des Poids et Mesures: The International System of Units (SI), 9th edition, version 4.01; National Institute of Standards and Technology: Definitions of the SI Units: The Binary Prefixes; National Institute of Standards and Technology: NIST Special Publication 330, Section 3: Decimal Multiples and Submultiples of SI Units.

Target unit: megabyte (MB). A megabyte uses the decimal SI prefix mega: 1 MB = 1000000 B exactly. Named variant used: Decimal megabyte; not mebibyte. Reference: Bureau International des Poids et Mesures: The International System of Units (SI), 9th edition, version 4.01; National Institute of Standards and Technology: Definitions of the SI Units: The Binary Prefixes; National Institute of Standards and Technology: NIST Special Publication 330, Section 3: Decimal Multiples and Submultiples of SI Units.

The GB-to-MB direction remains inside the data size quantity; it changes the unit label and numerical scale, not the kind of quantity being measured.

Relationship and precision

The named unit relationships are defined or exact, so the conversion is exact before display rounding and source-measurement uncertainty.

• GB relationship: The decimal-prefix relationship is exact.
• MB relationship: The decimal-prefix relationship is exact.

To audit the factor through the family base unit, divide the raw dataset factors 1000000000 by 1000000. The generator emits that quotient once at 15 significant digits as the canonical direct factor 1000; runtime calculations do not divide the already-emitted base factors again.

Reproducible example

For 10 gigabytes, 10 × 1000 = 10000 megabytes. Repeating the same multiplication with the stated factor reproduces the displayed conversion before interface rounding.

Directional scale check

Because one gigabyte contains 1000 megabytes, the target number is larger than the source number for every positive input. Zero maps to zero, while negative inputs are rejected because this family models non-negative magnitudes.

Interpretation

Read the result as megabytes, not gigabytes. A value entered as GB leaves the calculator labelled MB; this directional distinction matters even when the two units describe the same data size quantity.

Assumptions and limitations

• Only non-negative data-size values are accepted by this family.
• A conversion does not add significant figures to the source measurement.
• One byte is eight bits in this family; bit-rate and transfer-time conversions are outside scope.

Common mistakes

• 1 GB is 1000000000 B; a binary gibibyte is 1073741824 B.
• Mb denotes megabit, while MB denotes megabyte.

Continue within the Data Size family

See the Data Size conversion hub for its five-unit reference table and all 20 directed routes.

• Reverse the direction: Megabytes to Gigabytes
• Compare another data size route: Gigabytes to Bytes
• Compare another data size route: Gigabytes to Kilobytes
• Compare another data size route: Gigabytes to Kibibytes
• Compare another data size route: Megabytes to Bytes

Assumptions

• The entered value uses gigabytes exactly as labelled.
• Only non-negative data-size values are accepted by this family.
• Rounding and measurement uncertainty remain the user's responsibility.

Sources and methodology

CalcMotive publishes the formula and assumptions so you can decide whether the estimate fits your use case. See our methodology standards.

• The International System of Units (SI), 9th edition, version 4.01; Bureau International des Poids et Mesures; accessed Aug 7, 2026
• Definitions of the SI Units: The Binary Prefixes; National Institute of Standards and Technology; accessed Aug 7, 2026
• NIST Special Publication 330, Section 3: Decimal Multiples and Submultiples of SI Units; National Institute of Standards and Technology; accessed Aug 7, 2026