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Convert Gallons to Liters – Volume Converter

This converter translates volumes measured in US liquid gallons to liters using the internationally recognized definitions of the units. It is intended for everyday conversions, lab reporting, inventory tracking, and regulatory documentation where clear identification of the gallon type is required.

The tool uses the exact relationship between the US liquid gallon and the liter based on SI definitions of length and volume. Users who need conversions for other gallon definitions (for example imperial gallons) should use the appropriate converter or consult the notes below.

Results are presented with suggested rounding for readability but users should apply domain-specific rounding or uncertainty propagation for legal, trade, or laboratory reporting. See the methodology and FAQs for guidance on calibration, measurement uncertainty, and applicable standards.

Updated Nov 13, 2025

Interactive Converter

Convert between us gallon and liter with precision rounding.

Quick reference table

US GallonLiter
1 gal3.7854 L
5 gal18.9271 L
10 gal37.8541 L
25 gal94.6353 L
50 gal189.2705 L
100 gal378.541 L

Methodology

Unit definitions follow international standards: the liter is a derived SI unit equal to one cubic decimeter and US liquid gallon is defined via cubic inches with the international inch to meter relationship. The numeric conversion factor is derived from these exact definitions.

We reference national and international standards and guidance for units and reporting to ensure traceability: NIST guidance on SI use and unit definitions, ISO 80000 series on quantities and units, and general standards bodies for reporting conventions.

This tool performs a deterministic multiplication by the exact conversion factor. It does not add measurement uncertainty; users responsible for compliance must include instrument calibration and uncertainty calculations per their sector standards.

Worked examples

Example 1: 1 US gallon → 1 × 3.785411784 = 3.785411784 L (commonly rounded to 3.7854 L for display).

Example 2: 5 US gallons → 5 × 3.785411784 = 18.92705892 L (round as required, for example 18.9271 L).

Example 3 (imperial context): 1 imperial gallon → 4.54609 L (use the imperial factor only when the source explicitly states imperial gallons).

Expert Q&A

Which gallon does this converter use?

This converter uses the US liquid gallon (often abbreviated gal US). If you need an imperial (UK) gallon conversion, use a converter that specifies the imperial gallon or apply the imperial factor of 4.54609 L per imperial gallon.

Is the conversion factor exact or approximate?

The numeric factor 3.785411784 for the US liquid gallon to liter conversion is derived from exact definitions (231 in3 and 0.0254 m per inch) and is conventionally used as the exact factor for conversion. Displayed results may be rounded for readability.

How should I handle rounding and reporting for regulatory or lab use?

Round and report according to your domain requirements and the applicable standard. For laboratory and legal reporting include measurement uncertainty, instrument calibration status, and significant figures according to your lab protocol, ISO guidance, or national metrology office recommendations.

Does this tool account for measurement uncertainty or temperature effects?

No. This converter performs a mathematical unit conversion only. It does not account for measurement uncertainty, thermal expansion of liquids, or instrument calibration. For precision work, calculate uncertainty per ISO/IEC 17025, NIST guidance, or your organization's procedures and apply temperature corrections as needed.

Can I convert fuel volumes or mass-to-volume using this tool?

This tool converts volume units only. Converting between mass and volume requires density at the relevant temperature and pressure. Refer to product-specific density data and use a density-based calculation to convert between mass and volume.

Sources & citations