21 MPG (US) to L/100km
11.2 L/100km
21 mpg = 11.2 L/100km.
L/100km
11.2L/100km
21 mpg = 11.2 L/100km
The short answer
How many L/100km is 21 MPG (US)?
21 mpg = 11.2 L/100km. L/100km = 235.214583 ÷ MPG (US), so the working is 235.214583 ÷ 21 = 11.2.
The working
MPG (US) and L/100km are reciprocals of each other, so the conversion is a division rather than a multiplication — which is why the two scales never line up evenly.
L/100km = 235.214583 ÷ MPG (US) 235.214583 ÷ 21 = 11.2
How much precision do you need?
Each row is the same answer cut at a different number of decimals, with what that choice costs you. Pick the shortest row whose error is smaller than whatever you are measuring with.
| Rounded to | Answer (L/100km) | Off by |
|---|---|---|
| Whole number | 11 | −0.20069 |
| 1 decimal | 11.2 | −0.00069 |
| 2 decimals | 11.20 | −0.00069 |
Round trip: take 11.2 L/100km back the other way and you land on 21.0013 mpg — a drift of 0.0013 mpg. That gap is the rounding, not the conversion.
What 21 mpg looks like
20 mpg
The CAFE schedule Congress wrote required carmakers to reach a 20.0 mpg passenger car fleet average by model year 1980.
22 mpg
Any new American car rated below 22.5 mpg combined on the unadjusted test attracts the federal gas guzzler tax.
Frequently asked questions
What is 21 MPG (US) in L/100km?
21 MPG (US) is 11.2 L/100km. L/100km = 235.214583 ÷ MPG (US), so the working is 235.214583 ÷ 21 = 11.2.
How accurate is 11.2 L/100km?
Rounding to 11.2 L/100km and converting straight back gives 21.0013 mpg, a drift of 0.0013 mpg from the 21 you started with. The factor itself is exact; every bit of that difference comes from the rounding, not the conversion.
Nearby values
Any value at all
MPG to L/100km Converter
Convert US MPG to L/100km — read a car’s economy the way the rest of the world quotes it.
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