Fuel Economy Calculator
This fuel economy calculator turns your distance traveled and fuel used into a clear efficiency figure in every common format at once — L/100km, km/L, MPG (US), and MPG (UK). Enter two numbers and the result appears instantly, with a color-coded rating from Excellent to Poor.
It is built for drivers who want to budget fuel, compare cars on real-world mileage, watch for rising consumption that hints at maintenance, or plan a road trip. A second Trip Cost tab estimates what a journey will cost from your distance, consumption rate, and fuel price.
How to Calculate Your Fuel Economy
Choose your units
Pick Metric (kilometers, liters) or Imperial (miles, US gallons). Every input, label, and result updates automatically when you switch.
Enter the distance traveled
Type the distance for the trip, or tap a Quick distance preset. Presets adjust to your chosen unit system.
Enter the fuel used
Add the liters or gallons consumed over that distance. The result appears instantly in L/100km, km/L, MPG (US), and MPG (UK).
Read the efficiency rating
Check the gauge and rating badge to see where your vehicle lands — from Excellent to Poor — then switch to the Trip Cost tab to estimate fuel expenses.
Features
Economy From Distance & Fuel
Enter how far you drove and how much fuel you used, and your efficiency is calculated instantly.
Multi-Format Results
See L/100km, km/L, MPG (US), and MPG (UK) together — no manual converting between systems.
Visual Efficiency Gauge
A color-coded gauge and rating badge place your result from Excellent to Poor at a glance.
Trip Cost Estimator
Enter trip distance, consumption rate, and fuel price to see the total cost and fuel needed.
Cost Breakdown
The trip tab shows cost per kilometer or mile and cost per 100 km or 100 mi.
Metric & Imperial
Toggle between kilometers/liters and miles/US gallons; all fields and labels update automatically.
Quick Distance Presets
One-tap preset buttons fill common distances and adjust to your selected unit system.
Efficiency Reference
A built-in ratings reference shows what counts as good or poor economy in L/100km and MPG.
Frequently Asked Questions
How do I calculate fuel economy or MPG?
Divide the distance traveled by the fuel used. In imperial units, miles ÷ gallons gives you MPG. In metric units, the tool computes L/100km as (fuel used ÷ distance) × 100, plus km/L as distance ÷ fuel. Just enter the two numbers and every format is filled in for you.
How do I convert between MPG and L/100km?
The standard formulas are MPG (US) = 235.215 ÷ L/100km and MPG (UK) = 282.481 ÷ L/100km. Because they are inverse measures, a higher MPG matches a lower L/100km. The calculator applies these conversions automatically, so you never have to do the math.
What is a good fuel economy?
Below 7 L/100km (about 34 MPG US) is generally good for a passenger car, which this tool rates Excellent under 5 and Good under 7. Hybrids can reach under 5 L/100km equivalent, while larger SUVs and trucks often use 10–15 L/100km and land in the Below Average to Poor range.
What is the difference between MPG US and MPG UK?
The US gallon (3.785 liters) is smaller than the UK imperial gallon (4.546 liters), so the same vehicle shows a higher MPG UK number than MPG US. For example, 30 MPG US is roughly 36 MPG UK. The calculator displays both so you can compare figures quoted in either standard.
How do I estimate the fuel cost of a trip?
Open the Trip Cost tab and enter your trip distance, your vehicle's consumption rate (L/100km or MPG), and the current fuel price. The tool returns the total fuel cost, the fuel needed, and the cost per kilometer or mile plus per 100 km or 100 mi.
Why does my fuel economy vary between trips?
Real-world consumption shifts with driving style (hard acceleration and braking burn more), speed, terrain, traffic, vehicle load, tire pressure, and weather such as cold starts or air conditioning. That is why a single full-to-full measurement is more reliable than one short trip.
Is this calculator accurate?
It uses standard conversion factors and returns mathematically exact results from your inputs. For the most representative real-world figure, fill the tank completely before and after a test drive and use the odometer reading for distance, since the result is only as accurate as the numbers you enter.
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