Convert litres per 100 km to miles per gallon. Divide 235.21 by the consumption figure, with both gallons compared.

The formula

mpg (US)        = 235.2146 ÷ L/100km
mpg (imperial)  = 282.4809 ÷ L/100km

The same division as the reverse conversion, because the relationship is reciprocal and therefore its own inverse. See mpg to L/100km.

Quick reference

L/100km	mpg (US)	mpg (UK)	km/L
3.0	78.4	94.2	33.3
4.0	58.8	70.6	25.0
5.0	47.0	56.5	20.0
6.0	39.2	47.1	16.7
7.0	33.6	40.4	14.3
8.0	29.4	35.3	12.5
9.0	26.1	31.4	11.1
10.0	23.5	28.2	10.0
12.0	19.6	23.5	8.3
15.0	15.7	18.8	6.7

10 L/100 km is exactly 10 km/L, and it is the only point where the two agree.

Reading a European or Asian car’s figures

L/100 km is the unit on European type approval documents, on Taiwanese and Japanese specifications alongside km/L, and on most trip computers outside the US:

Class	L/100km	mpg (US)
Large SUV	12–15	15.7–19.6
Family petrol	7–9	26.1–33.6
Small petrol	5.5–6.5	36.2–42.8
Diesel	4.5–5.5	42.8–52.3
Hybrid	3.5–4.5	52.3–67.2

Consumption is the honest unit

L/100 km is linear in the thing you pay for. Halving it halves the fuel bill; halving the mpg does not double it.

L/100km	Fuel per 10,000 km	Change from the row above
12	1200 L	—
10	1000 L	−200 L
8	800 L	−200 L
6	600 L	−200 L
4	400 L	−200 L

Every two-litre step saves exactly 200 litres. The same table in mpg — 19.6, 23.5, 29.4, 39.2, 58.8 — has steps of 3.9, 5.9, 9.8 and 19.6, which look like accelerating gains and are not. See the MPG illusion on the fuel economy converter.

Which gallon the answer is in

This page’s default is the US gallon. If the figure is going into a British context, the expected unit is the imperial gallon, which produces a number 20% larger for the same car:

6 L/100km = 39.2 mpg (US) = 47.1 mpg (imperial)

Estimating in your head

Divide 235 by the number. 8 L/100 km → 235 ÷ 8 ≈ 29 mpg, against a true 29.4. For imperial, divide 282 instead.

L/100 km to mpg