Direct conversion
Convert gallon (UK) per 100 miles [gal/100 mi UK] to mile per gallon (UK) [mpg UK] instantly with formula, examples, chart, and FAQs.
Quick answer
Use the calculator below for any custom value, then check the formula, examples, chart, and reverse conversion links.
Fuel economy uses reciprocal conversion: 1 gallon (UK) per 100 miles [gal/100 mi UK] = 100 mile per gallon (UK) [mpg UK]. Enter any value for the exact reciprocal result.
Fuel economy uses reciprocal conversion: 1 gallon (UK) per 100 miles [gal/100 mi UK] = 100 mile per gallon (UK) [mpg UK]. Enter any value for the exact reciprocal result.
Example: 1 gallon (UK) per 100 miles [gal/100 mi UK] equals 100 mile per gallon (UK) [mpg UK].
Fuel consumption conversions use liter per 100 kilometers as the reference unit. Economy units such as mpg and km/L use reciprocal formulas.
Displayed results are rounded for readability. The calculator keeps enough precision for everyday use and switches to scientific notation for very large or very small values. Last reviewed: 2026-05-21.
The gallon (UK) per 100 miles (gal/100 mi UK) is a fuel consumption unit used to express measurements in this converter.
HistoryThis unit is included because it appears in practical measurement systems, technical references, product specifications, or everyday conversion needs.
Current useUse gallon (UK) per 100 miles when comparing fuel consumption values, checking specifications, converting between systems, or preparing quick estimates.
The mile per gallon (UK) (mpg UK) is a fuel consumption unit used to express measurements in this converter.
HistoryThis unit is included because it appears in practical measurement systems, technical references, product specifications, or everyday conversion needs.
Current useUse mile per gallon (UK) when comparing fuel consumption values, checking specifications, converting between systems, or preparing quick estimates.
| gallon (UK) per 100 miles [gal/100 mi UK] | mile per gallon (UK) [mpg UK] |
|---|---|
| 1 | 100 |
| 2 | 50 |
| 5 | 20 |
| 10 | 10 |
| 15 | 6.666667 |
| 20 | 5 |
| 25 | 4 |
| 30 | 3.333333 |
| 40 | 2.5 |
Use this formula: Fuel economy uses reciprocal conversion: 1 gallon (UK) per 100 miles [gal/100 mi UK] = 100 mile per gallon (UK) [mpg UK]. Enter any value for the exact reciprocal result. Enter your value in the calculator and the result updates instantly.
1 gallon (UK) per 100 miles [gal/100 mi UK] equals 100 mile per gallon (UK) [mpg UK].
Yes. Use the swap button in the calculator or open the related reverse conversion link when it is listed on this page.