Convert

Miles per US gallon to Miles per imperial gallon

Exact answer: mpg imp = mpg US × 1.200950 (inverse relationship, not a linear factor)

Miles per US gallon and Miles per imperial gallon run in opposite directions. A higher value in one unit means a lower one in the other. Consumption figures appear in vehicle data, test reports and travel cost calculations.

Unit console

Convert units with formula, context and precision

UnitCloud is a local measurement lab for everyday work, engineering, IT, energy, mobility and design. Every conversion shows result, formula, base unit, rounding and the common mistake.

What do you want to convert?

From10 mpg US

Result12.009499 mpg imp

FactorInverse formula

Source basisNIST Guide to SI Appendix B

Examples

0110 mpg US = 12.009499 mpg imp

Example value from the reference table. Internal calculation uses stored factors; display output is rounded.

02Common mistake

mpg and l/100 km move in opposite directions. Higher mpg means lower consumption; higher l/100 km means higher consumption.

03Base unit: l/100 km

Fuel units are normalised through litres per 100 kilometres; mpg and km/l are inverse values.

Table

Miles per US gallon to Miles per imperial gallon
Miles per US gallon	Miles per imperial gallon
10	12.009499
20	24.018999
30	36.028498
40	48.037997
50	60.047496
80	96.075994

Formula

Fuel units are normalised through litres per 100 kilometres; mpg and km/l are inverse values.

Sources

NIST Guide to SI Appendix BNIST conversion-factor method and non-SI factors.

Related conversions

Miles per US gallon to Litres per 100 kilometresmpg US → l/100 kmFuel economy Litres per 100 kilometres to Miles per US gallonl/100 km → mpg USFuel economy Miles per imperial gallon to Litres per 100 kilometresmpg imp → l/100 kmFuel economy Litres per 100 kilometres to Miles per imperial gallonl/100 km → mpg impFuel economy

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Factor origin

Factors come from the stored source family and are not derived from rounded display values.

Rounding rule

UnitCloud keeps calculating with stored factors and rounds only the displayed output by selected precision.

When not to use

Do not use as the sole basis for official, medical, safety-critical or contractual decisions.

Citation

Citation note: UnitCloud, conversion with formula, sources reviewed: September 2026. Fuel economy. Source basis: NIST Guide to SI Appendix B.

Common questions

Which formula applies to Miles per US gallon to Miles per imperial gallon?

mpg imp = mpg US × 1.200950

Which formula does Miles per US gallon to Miles per imperial gallon use?

Fuel units are normalised through litres per 100 kilometres; mpg and km/l are inverse values.

What is the most common mistake?

mpg and l/100 km move in opposite directions. Higher mpg means lower consumption; higher l/100 km means higher consumption.

When should I verify the result?

Do not use as the sole basis for official, medical, safety-critical or contractual decisions.