What fuel economy units does this calculator support?

The calculator supports mpg (US), mpg (UK), L/100km and km/L. It automatically converts between them so you can use the unit that matches your car's specification or your country.

How accurate is the fuel cost estimate?

The estimate is as accurate as the inputs you provide. Real-world fuel economy varies with speed, traffic, temperature, load and driving style. For better accuracy, use your actual average fuel consumption from recent fill-ups and the current fuel price in your area.

Fuel Cost Calculator

Q: How do I calculate fuel cost for a trip?

To calculate fuel cost for a trip, divide the trip distance by your vehicle's fuel efficiency to get the fuel used, then multiply by the fuel price. For example, if you drive 300 miles at 30 mpg and fuel costs $3.80 per gallon, fuel used = 300 ÷ 30 = 10 gallons and trip cost = 10 × 3.80 = $38.

Q: Can I estimate my monthly or yearly fuel cost?

Yes. Enter your average distance driven per day, week or month and your fuel economy and fuel price. The calculator will estimate your fuel cost per day, week, month and year based on your driving pattern.

Q: How do I get my real fuel economy?

Fill your tank completely and reset your trip odometer. Drive as usual, then refill the tank and note the distance driven and the amount of fuel added. Your real fuel economy is distance ÷ fuel used (e.g., miles ÷ gallons or km ÷ liters). Enter that value into the calculator.

Estimate how much you’ll spend on fuel for a single trip or your regular driving – with support for mpg, L/100km, km/L, US/UK gallons, and multiple currencies.

Fuel price

Use your local fuel price. Currency symbol is for display only.

Fuel economy

Use your real-world average if possible, not just the brochure value.

Show advanced options

Trip fuel cost

Trip distance

Number of people sharing cost

Use this to split the fuel bill between passengers.

Quick presets

How this fuel cost calculator works

This tool estimates how much you’ll spend on fuel for a specific trip or for your regular driving pattern. It works with both distance-per-fuel (mpg, km/L) and fuel-per-distance (L/100km) units and converts everything internally.

Core formulas

1. Convert fuel economy to liters per 100 km

From mpg (US): $ \text{L/100km} = \dfrac{235.214583}{\text{mpg (US)}} $
From mpg (UK): $ \text{L/100km} = \dfrac{282.480936}{\text{mpg (UK)}} $
From km/L: $ \text{L/100km} = \dfrac{100}{\text{km/L}} $

2. Fuel used for a trip

If distance is in km and economy in L/100km: $ \text{Fuel used (L)} = \dfrac{\text{distance (km)} \times \text{L/100km}}{100} $

If distance is in miles and economy in mpg (US): $ \text{Fuel used (gal)} = \dfrac{\text{distance (miles)}}{\text{mpg (US)}} $

3. Fuel cost

$ \text{Cost} = \text{Fuel used} \times \text{Fuel price per unit} $

Step-by-step: calculate trip fuel cost

Enter your local fuel price and choose whether it’s per liter, US gallon or UK gallon.
Enter your car’s fuel economy in mpg, L/100km or km/L.
In the Trip cost tab, enter the trip distance and unit (miles or km).
Optionally set how many people will share the cost.
Click Calculate trip cost to see:
- Total fuel cost for the trip
- Estimated fuel used
- Cost per person
- Cost per mile or per km

Estimate your monthly and yearly fuel budget

Switch to the Monthly / yearly cost tab to estimate your ongoing fuel expenses:

Enter how far you drive on average (e.g. 40 miles per day, 300 km per week).
Select whether that distance is per day, week or month.
Use the same fuel price and fuel economy as above.
Click Calculate fuel budget to get daily, weekly, monthly and yearly fuel costs.

Tips for more accurate estimates

Use real fuel economy: Calculate it from your last few fill-ups instead of relying on official ratings.
Update fuel price regularly: Prices can change quickly; use your latest receipt or local station price.
Consider conditions: Heavy traffic, cold weather, towing and high speeds all increase fuel consumption.
Average over time: For commuting, use an average distance per week or month rather than a single day.

FAQ

How do I get my real fuel economy?

Fill your tank completely and reset the trip odometer. Drive normally until your next fill-up, then:

Note the distance driven (miles or km).
Note how much fuel you added (gallons or liters).
Fuel economy = distance ÷ fuel used (e.g. 420 miles ÷ 14 gallons = 30 mpg).

What’s the difference between US mpg and UK mpg?

A UK (Imperial) gallon is larger than a US gallon (4.546 L vs 3.785 L), so the same car will show a higher mpg number in UK units. Make sure you choose the correct mpg type for your country.

Can I use this for electric cars?

Yes, approximately. Treat “fuel price” as the price per kWh and “fuel economy” as distance per kWh (or kWh per 100 km). The math is the same, but you’ll need to convert your EV’s consumption into compatible units first.