30 mpg (US) to L/100 km
- US miles per gallon (mpg (US))
- 30 mpg (US)
- Liters per 100 km
- 7.8404861111 L/100 km
Checked against: Exact-fraction computation from the legal unit definitions
US miles per gallon to liters per 100 km converter
Convert US miles per gallon to liters per 100 km (mpg to L/100km) with the exact formula, a conversion chart and worked steps.
By AdminDrafted with AI writing toolsUpdated Checked examples: 3
Liters per 100 km
L/100 km
Liters per 100 km: 7.84048611111 L/100 km
- Conversion
- 30 mpg (US) = 7.8404861111 L/100 km
- 1 L/100 km in US miles per gallon
- 235.2145833mpg (US)
30 mpg (US) is about 7.8404861111 L/100 km. In the other direction, 1 L/100 km ≈ 235.21458333 mpg (US).
US miles per gallon to liters per 100 km
Mpg to L/100km chart
| US miles per gallon | Liters per 100 km |
|---|---|
| 10 | 23.5215 |
| 15 | 15.681 |
| 20 | 11.7607 |
| 25 | 9.4086 |
| 30 | 7.8405 |
| 35 | 6.7204 |
| 40 | 5.8804 |
| 50 | 4.7043 |
| 60 | 3.9202 |
How it's calculated S
Apply the formula
About the US miles per gallon to liters per 100 km converter
A US miles-per-gallon rating describes distance traveled for a fixed fuel amount. Converting it to consumption per distance reverses the scale: a larger mpg value becomes a smaller liters-per-100-kilometers value. UK imperial mpg needs a different gallon definition.
mile per US gallon → litre per 100 km uses a reciprocal formula: fuel consumption per distance is the reciprocal of distance per fuel. For example, 30 mpg (US) is about 7.8405 L/100 km.
At 1 US mpg, fuel consumption is approximately 235.214583 L/100 km, calculated as 100 km × 3.785411784 L/US gal ÷ 1.609344 km/mi. Higher mpg means lower L/100 km, and the relationship is a curve, not a straight line.
How to convert mpg to L/100 km
Divide 235.215 by the US mpg figure: L/100 km = 235.214583… ÷ US mpg. So 30 mpg is 7.84 L/100 km and 50 mpg is 4.70 L/100 km. The conversion is reciprocal: higher mpg means fewer liters, and doubling the mpg halves the consumption.
Where 235.215 comes from
Miles per gallon is distance per unit of fuel, while L/100 km is fuel per fixed distance, so one is the inverse of the other.
A US gallon is 3.785411784 L and a mile is 1.609344 km, so 100 × 3.785411784 ÷ 1.609344 = 235.214583… (NIST SP 811, Appendix B).
UK figures use the imperial gallon of 4.54609 L (imperial definition), which makes the constant 282.481. For mental math, 235 ÷ US mpg is within 0.1%.
US mpg to L/100 km chart
| US mpg | Liters per 100 km |
|---|---|
| 10 | 23.521458 |
| 15 | 15.680972 |
| 20 | 11.760729 |
| 30 | 7.840486 |
| 40 | 5.880365 |
| 50 | 4.704292 |
Why each extra mpg saves less fuel
Because the scale is reciprocal, the same mpg step saves less fuel the higher you go. Moving from 10 to 20 mpg saves 11.76 L every 100 km; moving from 30 to 40 mpg saves only 1.96 L.
Doubling 30 mpg to 60 mpg cuts consumption from 7.84 to 3.920243 L/100 km. When the question is how much fuel you will buy, compare L/100 km, which rises in step with the fuel used.
Trip fuel and averages
Consumption multiplies directly by distance. At 30 mpg, a 500 km trip uses 5 × 7.8404861111 ≈ 39.202431 liters; the trip fuel cost calculator adds the price.
Averages work in L/100 km but not in mpg. Equal distances driven at 20 mpg and 40 mpg average 8.82 L/100 km, which is 26.67 mpg, not 30.
Common mistakes
- Applying the US constant to UK mpg. A UK rating of 40 mpg is 7.06 L/100 km; dividing 235.215 by 40 gives 5.88, about 17% too low.
- Looking for a multiplier. No single factor converts every value, because the answer falls as mpg rises. Divide the constant by the mpg each time.
- Converting MPGe. The MPGe on an electric car's label is an energy equivalent, not liters of fuel (FuelEconomy.gov).
Related fuel conversions
The L/100 km to mpg converter goes the other way, the fuel economy converter handles UK mpg and km/L, and the gas mileage calculator works out mpg from fill-ups.
Worked examples
25 mpg (US) to L/100 km
- US miles per gallon (mpg (US))
- 25 mpg (US)
- Liters per 100 km
- 9.4085833333 L/100 km
Checked against: Exact-fraction computation from the legal unit definitions
50 mpg (US) to L/100 km
- US miles per gallon (mpg (US))
- 50 mpg (US)
- Liters per 100 km
- 4.7042916667 L/100 km
Checked against: Exact-fraction computation from the legal unit definitions
Questions
What is the formula to convert mile per US gallon → litre per 100 km?
Divide 235.214583 by the value: 30 US mpg → 235.214583 ÷ 30 ≈ 7.84 L/100 km; 6 L/100 km → 235.214583 ÷ 6 ≈ 39.2 mpg. The same formula works in both directions because each unit is the reciprocal of the other, scaled. The constant shown is rounded.
About this calculator
Sources
Checked against references
This calculator includes 3 worked examples with independently sourced answers. They run in the test suite, and you can run them here too.