This fuel unit converter helps you instantly convert MPG, L/100km, KM/L, miles, kilometers, gallons and litres. Whether you are comparing fuel economy ratings from different countries or converting a trip distance, this calculator gives you accurate results using standard international conversion factors.

ou found a car’s fuel economy listed in a unit that means nothing to you. A US listing says 32 MPG, but you think in L/100km. A European spec sheet says 6.5 L/100km, but you only know MPG. Manually converting between unit systems means remembering constants and doing division by hand, which is easy to get wrong under pressure. We built this gas mileage converter so you get an instant, accurate result every time, no spreadsheet or manual math required.

Written by the FuelConsumptionCalc Research Team

Formulas and figures on this page are cross-checked against standard international unit conversion constants and EPA fuel economy data. Sources: EPA fuel economy data, international unit conversion standards (SI and Imperial systems).

Sources: See our full methodology page for how we verify every figure on this site.

Last Reviewed: June 2026

FUEL UNIT CONVERTER

Switch between MPG, L/100km, KM/L, miles, km, gallons and litres

L/100km = 235.214 ÷ MPG | KM/L = MPG × 0.425144

Value you know

Enter your starting figure

MPG

Unit of that value

Your Converted Result

Want to calculate MPG from a real fill-up instead? Try our MPG Calculator

Enter any MPG, L/100km, or KM/L value above and the converter instantly shows the equivalent figure in every other unit, with both US and UK gallon options for MPG.

KM = Miles × 1.60934 | Litres = US Gal × 3.78541 | Litres = UK Gal × 4.54609

Distance value (optional)

Convert miles ↔ kilometers

Distance unit

Volume value (optional)

Convert gallons ↔ litres

US gal

Volume unit

Your Converted Result

Planning a trip with your converted distance? Use our Trip Fuel Calculator

Enter a distance in miles or kilometers, a fuel volume in US gallons, UK gallons, or litres, or both at once, and your converted result appears instantly.

Quick Answer

L/100km = 235.214 / MPG
1 mile = 1.60934 km
1 US gallon = 3.78541 litres
1 UK gallon = 4.54609 litres

MPG (US)	L/100km	KM/L
20 MPG	11.8 L/100km	8.5 KM/L
25 MPG	9.4 L/100km	10.6 KM/L
30 MPG	7.8 L/100km	12.8 KM/L
35 MPG	6.7 L/100km	14.9 KM/L
40 MPG	5.9 L/100km	17.0 KM/L

How This Fuel Unit Converter Works

This calculator instantly switches between the three most common fuel economy formats used worldwide, MPG, L/100km, and KM/L. Enter any one value, MPG, L/100km, or KM/L, and the tool calculates the other two automatically using standard ternational conversion constants.

A separate section handles distance and volume conversions on their own,miles to kilometers and gallons to litres, useful when you are converting trip distances or fuel quantities rather than a full fuel economy rating. Our fuel consumption calculator uses these same constants internally, so figures stay consistent across every tool on this site.

Conversion Formulas Used

MPG to L/100km: L/100km = 235.214 / MPG
L/100km to MPG: MPG = 235.214 / L/100km
MPG to KM/L: KM/L = MPG x 0.425144
Miles to Kilometers: KM = Miles x 1.60934
Kilometers to Miles: Miles = KM x 0.621371
US Gallons to Litres: Litres = US Gallons x 3.78541
UK Gallons to Litres: Litres = UK Gallons x 4.54609

Example Conversions

A car rated at 32 MPG (US) converts as follows.

L/100km = 235.214 / 32 = 7.35 L/100km
KM/L = 32 x 0.425144 = 13.6 KM/L

A trip of 450 kilometers converts to miles as follows.

Miles = 450 x 0.621371 = 279.6 miles

If you are planning that same 450 km trip, our trip fuel calculator takes your converted distance directly and estimates fuel needed and total cost.

How to Use This Converter

Pick what you are converting from, MPG, L/100km, distance, or volume,enter your known value, and your converted result appears instantly in every other relevant unit.

Pick What You Are Converting

Choose between Fuel Economy (MPG, L/100km, KM/L) or Distance and olume (miles, km, gallons, litres) using the tabs above the calculator. Each tab handles a different type of conversion since fuel economy and simple distance or volume units use different formulas.

Enter Your Known Value

Type in whatever figure you lready have, a manufacturer’s MPG rating, a European L/100km spec, or a trip distance in either miles or kilometers.You only need one value, the calculator fills in very equivalent unit automatically.

Read Your Converted Result

Your result shows all relevant units at once, so you can reference whichever one matches the context you are orking in. Use your MPG calculator or L/100km calculator if you want to calculate a resh fuel economy figure from an ctual fill-up rather than converting a number you already have.

Distance and Volume Unit Reference

One mile equals 1.60934 kilometers. One US gallon equals 3.78541 litres.One UK gallon equals 4.54609 litres, which is meaningfully larger than a US gallon and a common source of conversion errors.

Miles to Kilometers

Multiply your mile figure by 1.60934 to get kilometers. A 100 mile trip converts to 160.9 kilometers.

Kilometers to Miles

Multiply your kilometer figure by 0.621371 to get miles. A 100 kilometer trip converts to 62.1 miles.

US Gallons to Litres

Multiply your US gallon figure by 3.78541 to get litres. A 15 US gallon tank holds 56.8 litres.

UK Gallons to Litres

Multiply your UK gallon figure by 4.54609 to get litres. A 15 UK gallon tank holds 68.2 litres, noticeably more than the same number of US gallons.

US Gallon vs UK Gallon, Why It Matters

A US gallon and a UK imperial gallon are not the same volume, despite sharing the name. A US gallon equals 3.78541 litres, while a UK gallon equals 4.54609 litres, about 20 percent larger. This means an MPG figure calculated using US gallons is not directly comparable to one calculated using UK gallons, even if both say “MPG.”

A vehicle rated at 40 MPG using US gallons would show a different,higher number if the same fuel consumption were expressed in MPG using UK gallons, since each UK gallon represents more actual fuel. Always confirm which gallon definition a source is using before comparing MPG figures across countries. Our km/l calculator sidesteps this ambiguity entirely, since kilometers per litre does not depend on gallon size at all.

Converting US MPG to UK MPG

Since US and UK gallons are different volumes, converting an MPG figure between the two systems uses a separate ratio rather than the L/100km constant.

US MPG to UK MPG: UK MPG = US MPG x 1.20095
UK MPG to US MPG: US MPG = UK MPG x 0.83267

A vehicle rated at 30 MPG (US) converts to 30 x 1.20095, which equals 36.0 MPG (UK). The same vehicle would never show “30 MPG” on a UK specification sheet, since UK gallons hold more fuel, so the same distance per tank produces a higher MPG number when calculated using the UK gallon. This is purely a unit conversion, the vehicle’s actual fuel efficiency has not changed.

Common Conversion Mistakes to Avoid

Mixing up US and UK gallons is the most frequent error, since both use the word “gallon” but represent different volumes. Always check the source country before treating two MPG figures as directly comparable. Rounding too early in a multi-step conversion compounds small errors into larger ones by the final result. Carry full decimal precision through each step and round only the final answer.

orgetting that L/100km is inverted compared to MPG catches many people switching between systems for the first time. A lower L/100km number means better efficiency, while a lower MPG number means worse efficiency, the exact opposite relationship. Confusing fuel economy conversion with fuel cost conversion is another common mix-up. This page converts units of efficiency, not money. Use our fuel cost calculator once you have your converted MPG or L/100km figure and want an actual dollar cost for a trip.

Fuel Economy Conversion Reference Table

MPG (US)	L/100km	KM/L	MPG (UK)
10 MPG	23.5 L/100km	4.3 KM/L	12.0 MPG
15 MPG	15.7 L/100km	6.4 KM/L	18.0 MPG
20 MPG	11.8 L/100km	8.5 KM/L	24.0 MPG
25 MPG	9.4 L/100km	10.6 KM/L	30.0 MPG
30 MPG	7.8 L/100km	12.8 KM/L	36.0 MPG
35 MPG	6.7 L/100km	14.9 KM/L	42.0 MPG
40 MPG	5.9 L/100km	17 .0 KM/L	48.0 MPG
45 MPG	5.2 L/100km	19.1KM/L	54.0 MPG
50 MPG	4.7 L/100km	21.3 KM/L	60.1 MPG
60 MPG	3.9 L/100km	25.5 KM/L	72.1 MPG

Methodology

Conversions on this page use internationally standardized constants. MPG to L/100km uses 235.214 as the conversion constant. MPG to KM/L uses 0.425144. Miles to kilometers uses 1.60934. US gallons to litres uses 3.78541. UK gallons to litres uses 4.54609. These figures are sourced from EPA fuel economy data and tandard SI and Imperial unit definitions.

Frequently Asked Questions

Divide 235.214 by your MPG figure to get the equivalent L/100km. A car rated at 30 MPG converts to 235.214 divided by 30, which equals 7.84 L/100km. This constant works specifically for US gallon based MPG figures, since the underlying conversion accounts for the US gallon definition of 3.78541 litres. If your MPG figure comes from a UK source using imperial gallons, the same formula will not produce an accurate result without first adjusting for the different gallon size.

Divide 235.214 by your L/100km figure to get the equivalent MPG. A car averaging 7 L/100km converts to 235.214 divided by 7, which equals 33.6 MPG. This is the exact reverse of the MPG to L/100km conversion, using the same constant in both directions. The calculator above performs this instantly and shows your KM/L figure at the same time, so you get all three common formats from a single entry.

It depends on which gallon you mean. A US gallon equals 3.78541 litres,the standard used throughout the United States for fuel pricing and tank capacity. A UK imperial gallon equals 4.54609 litres, about 20 percent larger than the US gallon, and is the standard historically used across the United Kingdom and some Commonwealth countries. Always confirm hich gallon definition applies to your specific source before converting, since using the wrong constant produces a meaningfully incorrect result.

No, they are different volumes despite sharing the same name. A UK imperial gallon equals 4.54609 litres, while a US gallon equals 3.78541 litres, making the UK gallon roughly 20 percent larger. This difference means MPG figures alculated using UK gallons are not directly comparable to MPG figures calculated using US gallons, even though both are expressed in the same unit name. A vehicle could show two different MPG numbers depending on which gallon definition was used in the underlying calculation, despite representing the exact same fuel efficiency.

Multiply your mile figure by 1.60934 to get the equivalent distance in kilometers. A 50-mile trip converts to 50 times 1.60934, which equals 80.5 kilometers. This constant is based on the internationally defined length of one mile, which is fixed at exactly 1,609.344 meters. The reverse conversion, kilometers to miles, multiplies by 0.621371 instead, the mathematical inverse of the miles to kilometers constant.

Multiply your MPG figure by 0.425144 to get the equivalent KM/L. A vehicle rated at 30 MPG converts to 30 times .425144, which equals 12.75 KM/L. This constant accounts for both the mile to kilometer conversion and the US gallon to litre conversion combined into a single multiplier,which is why it differs from the simpler mile and gallon constants used individually elsewhere on this page.

SSmall differences usually come from rounding at different stages of the calculation, or from a site using a slightly different precision for the underlying constants. Some sites also default to UK gallon based MPG without stating it clearly, which produces noticeably different results from US gallon based MPG for the same fuel efficiency. This calculator uses full-precision standard constants and clearly separates US and UK gallon figures to avoid that specific source of confusion.