Imperial Gallons (imp gal) to US Gallons (gal)

Imperial Gallons (imp gal) to US Gallons (gal) conversion guide

Imperial Gallons (imp gal) to US Gallons (gal) expresses the same volume in a different unit. The direction matters: a value given in Imperial Gallons (imp gal) is multiplied by the source-to-target factor to obtain US Gallons (gal). Keep the original measurement and its unit together when copying a result into a calculation.

Conversion formula using calculator presets

This calculator uses fixed unit coefficients, some rounded. The factor and examples below reproduce those presets rather than asserting exact conventional equivalence. Small differences from a standards-based conversion can remain even before display rounding.

Value in US Gallons (gal) = value in Imperial Gallons (imp gal) × (454609 / 378541). The factor is approximately 1.200950491. Derive it by dividing the source unit value in the base unit by the destination unit value in the same base unit.

About these units

Imperial Gallons (imp gal): The Imperial liquid measure is used. It differs from the US liquid unit with a similar name. The calculator uses a fixed coefficient that may be rounded; its preset is not a claim that this rounded number is the exact conventional definition. The source coefficient shown below is the calculator preset. The source preset corresponds to 0.00454609 cubic meters.

US Gallons (gal): The US customary liquid measure is used. A US legal nutrition-labeling cup or spoon may use a different rounded metric definition. The calculator uses a fixed coefficient that may be rounded; its preset is not a claim that this rounded number is the exact conventional definition. The destination coefficient shown below is the calculator preset. The destination preset corresponds to 0.00378541 cubic meters.

Worked examples

• 1 Imperial Gallons (imp gal) = approximately 1.200950491 US Gallons (gal)
• 2.5 Imperial Gallons (imp gal) = approximately 3.002376229 US Gallons (gal)
• 10 Imperial Gallons (imp gal) = approximately 12.00950491 US Gallons (gal)

Precision and interpretation

Examples are rounded for display. Keep the unrounded factor for intermediate calculations and round the final answer to match the precision of the original measurement. Extra decimal places do not make a measured quantity more accurate.

Volume and mass are different quantities. A conversion to grams or kilograms requires density. Do not mix US liquid and Imperial definitions.

Common questions

How do I reverse this conversion?

Divide the target-unit value by the forward factor, or use the inverse converter. Multiplying by the same factor again is not the inverse operation.

Why can the displayed answer differ slightly?

Display rounding and numerical precision can produce a small difference from an exact fractional calculation. For technical work, retain sufficient precision and confirm the unit convention required by the source.

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