Toolarithm

Fuel Economy Converter

Fuel Economy Converter

Convert vehicle fuel economy labels across US mpg, imperial mpg, kilometers per liter, and liters per 100 kilometers. The tool makes reciprocal fuel-consumption units visible so lower L/100 km values are not confused with higher mpg values.

Live converter

Fuel economy inputs

Convert distance-per-fuel and fuel-per-distance labels across US mpg, imperial mpg, kilometers per liter, and liters per 100 kilometers.

mpg (US)

Converted result

7.84048611111 L/100 km

Input

30 mpg (US)

Output unit

L/100 km

Base method

km per liter

Liters per 100 kilometers is an inverse fuel-consumption unit, so lower numbers indicate better economy.

Fuel economy in every supported unit

UnitConverted valueUnit nameNote
mpg (US)30Miles per US gallonDistance per US liquid gallon.
mpg (Imp)36.0284977651Miles per imperial gallonDistance per imperial gallon.
km/L12.7543112229Kilometers per literDistance per liter.
L/100 km7.84048611111Liters per 100 kilometersFuel consumed per 100 kilometers; lower is better.

Base route

km/L

Supported units

4

Includes

mpg + L/100 km

No sign-upFormula shownPrint-friendly
What Can You Create?

Compare vehicle efficiency labels without mixing systems

Car research

Compare listings or reviews that quote US mpg, imperial mpg, km/L, or L/100 km.

Trip notes

Convert dashboard or manual readings into the label used by your budget, region, or spreadsheet.

Fleet checks

Keep reciprocal fuel-consumption values visible when comparing mixed vehicle data sources.

Formula

Fuel economy conversion formula

The converter uses kilometers per liter as the base route. Liters per 100 kilometers is the reciprocal form, so it must be inverted rather than multiplied by a simple factor.

Working formulas

US mpg to km/L

km/L = mpg x 1.609344 / 3.785411784

One mile is 1.609344 km and one US gallon is 3.785411784 L.

km/L to L/100 km

L/100 km = 100 / km/L

This reciprocal step is why lower L/100 km values indicate better economy.

Imperial mpg to km/L

km/L = mpg(Imp) x 1.609344 / 4.54609

Imperial gallons are larger than US liquid gallons.

Symbols

mpg - miles per gallon
Distance traveled per gallon of fuel.
L/100 km - fuel consumed per distance
Liters needed to travel 100 kilometers.
Why Users Love This Tool

Why fuel economy conversions need the inverse check

Prevents direction mistakes

  • Higher mpg and km/L values are better, while lower L/100 km values are better.
  • The table keeps all four labels visible so the reciprocal relationship is easier to audit.
  • US and imperial gallons are separate, preventing a common vehicle-listing mismatch.

Better vehicle comparisons

  • Regional ratings can be translated into the unit used by your spreadsheet or buying checklist.
  • The method uses exact mile, US gallon, and imperial gallon relationships.
  • Trip-computer readings can be compared with published ratings without manual formula work.
Perfect For

Useful for vehicle and travel decisions

Car shoppers

Translate fuel economy labels when comparing vehicles from different countries or review sources.

Fleet managers

Normalize mixed mpg and L/100 km records before cost or emissions analysis.

Travel planners

Convert efficiency assumptions before estimating fuel use for road trips.

How It Works

How it works in three quick steps.

1

Enter the vehicle rating

Type the fuel economy value from a window sticker, manual, trip computer, or comparison table.

2

Choose fuel economy labels

Select US mpg, imperial mpg, kilometers per liter, or liters per 100 kilometers.

3

Check the inverse unit

Remember that L/100 km measures fuel consumed per distance, so a lower value is better.

Download & Print

Save fuel economy comparisons

Copy labeled results

Copy the selected conversion with source and target unit labels for recipes, vehicle notes, utility comparisons, or homework.

Print the comparison table

Print the full table when repeated conversions need to stay visible at a counter, desk, shop, lab, or classroom.

Keep the method nearby

Use the formula notes to confirm whether the converter used milliliters, km/L, joules, or watts as the base route.

FAQ

Frequently Asked Questions

Why is L/100 km lower when fuel economy is better?
Liters per 100 kilometers measures fuel consumed over a fixed distance. A smaller value means the vehicle needs less fuel to travel the same distance. MPG and km/L work in the opposite direction because they measure distance traveled per fuel volume.
Is US mpg the same as imperial mpg?
No. A US liquid gallon is 3.785411784 liters, while an imperial gallon is 4.54609 liters. The same vehicle can therefore show a different mpg number depending on which gallon definition was used.
What base unit does this converter use?
The converter normalizes each value to kilometers per liter. MPG values are converted with exact mile and gallon relationships, while L/100 km is inverted into km/L before being converted into the target unit.
Can this converter estimate trip fuel cost?
This page only converts fuel economy labels. To estimate trip cost, combine the converted fuel economy with trip distance and local fuel price. L/100 km is often convenient for consumption estimates because it already expresses fuel per fixed distance.
Why do official ratings differ from real driving?
Published ratings are measured under specific test cycles. Real-world fuel use can change with speed, terrain, traffic, cargo, tires, temperature, and driving style. Use the converter to compare labels, not to guarantee actual consumption.
About This Tool

About this fuel economy converter

Fuel economy labels are not all the same kind of measurement. Miles per gallon and kilometers per liter describe distance per fuel volume, so bigger numbers are better. Liters per 100 kilometers describes fuel volume per distance, so smaller numbers are better. Treating all labels as direct multipliers can reverse the meaning of a result.

This converter uses kilometers per liter as the internal route because it provides a clear bridge between distance-per-fuel units and L/100 km. US mpg uses the US liquid gallon, imperial mpg uses the imperial gallon, and L/100 km is converted with a reciprocal formula. That makes the table useful for car research, fleet notes, road-trip estimates, and spreadsheet cleanup.

Editorial Transparency

Who maintains this page

Ownership and review

Written and maintained by the Toolarithm editorial team. No review date is shown without a maintained editorial record. No independent professional review is claimed.

Methodology

Conversion factors are normalized to canonical units and checked in both directions. Exact definitions and offset formulas are preferred over rounded lookup values.

Read the editorial methodology

Dates and sources

Review dates change only after a substantive method or content check.

Keep building

Explore more unit converters

Converters