Direct conversion
Convert gallon (US) per 100 miles [gal/100 mi US] to mile per gallon (US) [mpg US] 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 (US) per 100 miles [gal/100 mi US] = 100 mile per gallon (US) [mpg US]. Enter any value for the exact reciprocal result.
Fuel economy uses reciprocal conversion: 1 gallon (US) per 100 miles [gal/100 mi US] = 100 mile per gallon (US) [mpg US]. Enter any value for the exact reciprocal result.
Example: 1 gallon (US) per 100 miles [gal/100 mi US] equals 100 mile per gallon (US) [mpg US].
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 (US) per 100 miles (gal/100 mi US) 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 (US) per 100 miles when comparing fuel consumption values, checking specifications, converting between systems, or preparing quick estimates.
Miles per US gallon measures how many miles a vehicle travels using one US gallon of fuel.
HistoryMPG became common in countries using miles and US liquid gallons for driving and fuel sales.
Current useMPG is used for vehicle economy, car shopping, fuel budgeting, and comparing engine efficiency.
| gallon (US) per 100 miles [gal/100 mi US] | mile per gallon (US) [mpg US] |
|---|---|
| 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 (US) per 100 miles [gal/100 mi US] = 100 mile per gallon (US) [mpg US]. Enter any value for the exact reciprocal result. Enter your value in the calculator and the result updates instantly.
1 gallon (US) per 100 miles [gal/100 mi US] equals 100 mile per gallon (US) [mpg US].
Yes. Use the swap button in the calculator or open the related reverse conversion link when it is listed on this page.