Comparing cars across markets
A car rated 30 US MPG is 7.84 L/100km. The same car sold in the UK might be advertised at 36 MPG because the Imperial gallon is larger — the vehicle is identical.
Fuel Economy
Convert mpg to l/100km
1 mile per gallon (us) equals 235.21458 liters per 100 km. Enter a value below to convert instantly.
Miles per gallon to litres per 100 km is not a multiplication — it is a reciprocal. MPG measures distance per unit of fuel and L/100km measures fuel per unit of distance, so as one rises the other falls. This page uses the US gallon; UK MPG figures are about 20% higher for the same car.
1 mpg (US)
235.21458 L/100km
Mile per Gallon (US) and Liter per 100 km are related through the category's base unit. Distance-per-fuel and fuel-per-distance measures are reciprocals, so the calculation inverts the value where needed. How this is calculated
Need the other direction? Convert liter per 100 km to mile per gallon (us) →
Formula
Mile per Gallon (US) and Liter per 100 km are related through the category's base unit. Distance-per-fuel and fuel-per-distance measures are reciprocals, so the calculation inverts the value where needed.
Not a simple multiplication. One of these units is a reciprocal of the other's quantity, so the conversion inverts the value instead of scaling it.
Step by step
- Start with 1 mpg (US).
- Apply the Mile per Gallon (US)-to-Liter per 100 km formula.
- The result is 235.21458 L/100km.
Miles per Gallon (US) to Liters per 100 km conversion table
| Miles per Gallon (US) (mpg (US)) | Liters per 100 km (L/100km) |
|---|---|
| 5 | 47.042917 |
| 10 | 23.521458 |
| 15 | 15.680972 |
| 20 | 11.760729 |
| 25 | 9.4085833 |
| 30 | 7.8404861 |
| 40 | 5.8803646 |
| 50 | 4.7042917 |
| 60 | 3.9202431 |
Where miles per gallon (us) and liters per 100 km are used together
Judging the value of an upgrade
Going from 15 to 20 MPG saves 1.67 gallons per 100 miles. Going from 40 to 50 MPG saves only 0.5 gallons per 100 miles, despite being a larger MPG jump. This is the 'MPG illusion', and it is why US labels now also show gallons per 100 miles.
Budgeting fuel for a trip
L/100km makes the arithmetic direct: 8 L/100km over a 600 km trip is 48 litres. Doing the same from MPG requires dividing rather than multiplying, which is why consumption units are preferred for planning.
Fleet and emissions reporting
CO₂ output is proportional to fuel burned per distance, so it tracks L/100km linearly and MPG inversely. Regulatory targets are therefore set in consumption or emissions terms, not in MPG.
Everyday miles per gallon (us) worth knowing
Values people actually look up, with the reason each one comes up. Every figure is calculated with the same engine as the converter above.
| Mile per Gallon (US) (mpg (US)) | Liter per 100 km (L/100km) | What it is |
|---|---|---|
| 15 | 15.680972 | A large SUV or truck |
| 20 | 11.760729 | A large vehicle |
| 25 | 9.4085833 | A mid-size car |
| 30 | 7.8404861 | An efficient mid-size car |
| 35 | 6.7204167 | A compact car |
| 40 | 5.8803646 | A very efficient car |
| 50 | 4.7042917 | A hybrid |
| 60 | 3.9202431 | A high-efficiency hybrid |
How these two units are defined
Fuel economy (MPG, km/L) is distance divided by fuel; fuel consumption (L/100km) is fuel divided by distance. They describe the same thing inverted, which is why converting between them means dividing rather than multiplying. The constant for US gallons is 235.215; for Imperial gallons it is 282.481, because an Imperial gallon is 20% larger. Test procedures differ too — EPA, WLTP and JC08 cycles produce different figures for the same vehicle, and no unit conversion reconciles them.
Rounding and precision
Because the relationship is reciprocal, precision behaves unevenly: at low consumption a small change in L/100km moves the MPG figure a lot, while at high consumption it barely moves it. Quote two significant figures for MPG and one decimal place for L/100km. Remember too that any published figure is a test-cycle result — real-world economy varies with driving style, load, temperature and terrain by considerably more than any rounding here.
Mistakes people make with this conversion
-
Converting as if it were linear
Doubling MPG halves L/100km; it does not double it. Any conversion that multiplies rather than divides is wrong.
-
Mixing US and UK MPG
35 US MPG is 42 UK MPG for the same car. UK figures look better purely because the Imperial gallon is 20% larger.
-
Averaging MPG figures directly
The average of 20 MPG and 40 MPG over equal distances is not 30 MPG — it is 26.7, because you must average the consumption, not the economy. Averaging L/100km works correctly.
Read more about these units
Sources for this page
- Learn More About the Fuel Economy Label for Gasoline Vehicles
- Special Publication 811 — Guide for the Use of the International System of Units (SI)
Content on this page last reviewed 12 August 2026. Spotted an error? Report it — see also how these values are calculated.
Convert Mile per Gallon (US) to other fuel economy units
1 mpg (US) expressed in every other fuel economy unit on this site.
- Kilometer per Liter km/L 0.42514371
- Meter per Liter m/L 425.14371
- Kilometer per Gallon (US) km/gal (US) 1.609344
- Mile per Liter mi/L 0.26417205
- Mile per Gallon (US) mpg (US) 1
- Mile per Gallon (UK) mpg (UK) 1.2009499
- Nautical Mile per Liter nmi/L 0.22955924
- Nautical Mile per Gallon (US) nmi/gal (US) 0.86897624
- Centimeter per Liter cm/L 42,514.371
- Dekameter per Liter dam/L 42.514371
- Hectometer per Liter hm/L 4.2514371
- Megameter per Liter Mm/L 0.00042514371
- Gigameter per Liter Gm/L 4.2514371e-7
- Terameter per Liter Tm/L 4.2514371e-10
- Petameter per Liter Pm/L 4.2514371e-13
- Exameter per Liter Em/L 4.2514371e-16
- Meter per Gallon (US) m/gal (US) 1,609.344
- Meter per Gallon (UK) m/gal (UK) 1,932.7416
- Meter per Quart (US) m/qt (US) 402.336
- Meter per Quart (UK) m/qt (UK) 483.18539
- Meter per Pint (US) m/pt (US) 201.168
- Meter per Pint (UK) m/pt (UK) 241.59269
- Meter per Cup (US) m/cup (US) 100.584
- Meter per Cup (UK) m/cup (UK) 120.79635
- Meter per Fluid Ounce (US) m/fl oz (US) 12.573
- Meter per Fluid Ounce (UK) m/fl oz (UK) 12.079635
- Meter per Cubic Meter m/m³ 425,143.71
- Meter per Cubic Yard m/yd³ 325,045.69
- Meter per Cubic Foot m/ft³ 12,038.729
- Meter per Cubic Inch m/in³ 6.9668571
- Liter per 100 km L/100km 235.21458
- Liter per Kilometer L/km 2.3521458
- Liter per 10 km L/10km 23.521458
- Gallon (US) per 100 mi gal/100mi (US) 100
- Gallon (US) per Mile gal/mi (US) 1
- Gallon (UK) per 100 mi gal/100mi (UK) 83.267418
- Gallon (UK) per Mile gal/mi (UK) 0.83267418
About the mile per gallon (us)
The mile per gallon (us) (mpg (US)) is a US unit of fuel economy. The US window-sticker figure, based on the 3.785 L US gallon.
About the liter per 100 km
The liter per 100 km (L/100km) is a Metric unit of fuel economy. The standard European consumption figure — lower is better.
Related conversions
Frequently asked questions
What is the formula for MPG to L/100km?
L/100km = 235.215 ÷ MPG for US gallons, or 282.481 ÷ MPG for Imperial gallons. The constants fold the gallon-to-litre and mile-to-kilometre conversions into a single number.
Why is going from 15 to 20 MPG worth more than 40 to 50?
Over 100 miles, 15 MPG burns 6.67 gallons and 20 MPG burns 5 — a saving of 1.67 gallons. At 40 and 50 MPG the figures are 2.5 and 2, a saving of only 0.5 gallons. MPG compresses the differences at the efficient end, which is why US fuel labels also show gallons per 100 miles.
Is this US or UK MPG?
This page uses US MPG, based on the 3.785 L US gallon. For UK figures use the Imperial MPG converter — the same car reads about 20% higher in UK MPG.
How many liters per 100 km are in a mile per gallon (us)?
One mile per gallon (us) equals 235.21458 liters per 100 km.
How do you convert miles per gallon (us) to liters per 100 km?
Mile per Gallon (US) and Liter per 100 km are related through the category's base unit. Distance-per-fuel and fuel-per-distance measures are reciprocals, so the calculation inverts the value where needed.
What is 1 liter per 100 km in miles per gallon (us)?
One liter per 100 km equals 235.21458 miles per gallon (us).
When would I convert miles per gallon (us) to liters per 100 km?
This conversion is common when comparing vehicle efficiency across countries.