Is higher mpg better or worse?

Higher mpg is better — your car covers more miles per gallon of fuel. Lower L/100km is better for the same reason (less fuel used per 100 km driven).

Why is the conversion reciprocal instead of linear?

Because the units encode fuel consumption from opposite directions. mpg measures "distance per unit of fuel" (more is better); L/100km measures "fuel per unit of distance" (less is better). The two are mathematically inversely related, so the conversion is a division, not a multiplication.

Are US and UK gallons the same in mpg calculations?

No — this calculator uses US gallons (1 US gal = 3.785411784 L). A car rated 30 US mpg is rated about 36 UK mpg (1 imperial gal = 4.54609 L). If you need imperial mpg, multiply US mpg by 1.20095.

Unit converter — Fuel consumption

Miles per US gallon to kilometers per liter converter

Convert miles per US gallon (mpg) to kilometers per liter (km/L). Reciprocal relationship — more fuel used per distance gives lower mpg.

Results are mathematically exact for the displayed precision. How we calculate.

How it's calculated

Convert miles per US gallon to kilometers per liter— the formula

Fuel consumption is reciprocal — more fuel used per distance means lower miles per US gallon and higher L/100km. The conversion goes through L/100km as a canonical form.

Step 1: L/100km = 235.214583 ÷ mpg

Step 2: km/L = 100 ÷ (L/100km)

Reciprocal relationship (more fuel = lower mpg = higher L/100km). US mpg ↔ L/100km via 235.214583 = (3.785411784 L/gal × 100 / 1.609344 km/mi). km/L = 100 / L/100km.

Questions

Frequently asked questions

Is higher mpg better or worse?
Higher mpg is better — your car covers more miles per gallon of fuel. Lower L/100km is better for the same reason (less fuel used per 100 km driven).
Why is the conversion reciprocal instead of linear?
Because the units encode fuel consumption from opposite directions. mpg measures "distance per unit of fuel" (more is better); L/100km measures "fuel per unit of distance" (less is better). The two are mathematically inversely related, so the conversion is a division, not a multiplication.
Are US and UK gallons the same in mpg calculations?
No — this calculator uses US gallons (1 US gal = 3.785411784 L). A car rated 30 US mpg is rated about 36 UK mpg (1 imperial gal = 4.54609 L). If you need imperial mpg, multiply US mpg by 1.20095.