Fuel Cost Calculator for Trips and Commutes
This fuel cost calculator turns a distance, your car's fuel efficiency and the price of fuel into the total fuel cost and the amount of fuel you need. It works in US miles per gallon (MPG), in liters per 100 km or in kilometers per liter, and it can scale one trip up to a round trip, a work week, a month or a year of commuting. There is no button to press: the result updates as you type. Every figure is calculated on your device and nothing is uploaded.
How to calculate fuel cost for a trip
- Choose your Unit system: US (MPG), L/100 km or km/L. It starts from your region, so US visitors begin with MPG.
- Enter the Distance, one way, in miles or kilometers.
- Enter your Fuel efficiency in the unit you chose. The fuel computer in your car or your last fill-up gives a realistic figure.
- Enter the Fuel price per US gallon or per liter, in the currency of the total shown.
- Read Total fuel cost and Fuel needed at the top.
Each of the three number fields must be greater than 0. Until all three are, the result shows a dash, and a field with an unusable value says "Enter a number greater than 0." Each unit system keeps its own efficiency value, so you can switch between MPG, L/100 km and km/L without retyping.
The fuel cost formula for MPG, L/100 km and km/L
Fuel needed is the distance divided by your efficiency, or for L/100 km the distance divided by 100 and multiplied by the efficiency. The cost is that fuel multiplied by the price.
| Unit system | Fuel used | Cost |
|---|---|---|
| US (MPG) | miles ÷ MPG = gallons | gallons × price per gallon |
| L/100 km | km ÷ 100 × L/100 km = liters | liters × price per liter |
| km/L | km ÷ km/L = liters | liters × price per liter |
Two worked examples, both for one way:
Fuel needed = 30 ÷ 25 = 1.2 gal
Total fuel cost = 1.2 × 3.50 = 4.20
Fuel needed = 50 ÷ 100 × 7.8 = 3.9 L
Total fuel cost = 3.9 × 1.85 = 7.215, shown as 7.22
Fuel cost for a commute: week, month and year
Always enter the distance one way. The Frequency dropdown does the multiplying, and the line under it, "Your distance is counted N times.", shows the multiplier it used. The fuel needed and the total both scale with it.
| Frequency | Distance counted | 30 mi, 25 MPG, 3.50/gal |
|---|---|---|
| One way | 1 time | 4.20 |
| Round trip | 2 times | 8.40 |
| Work week (round trips) | 10 times (5 days there and back) | 42.00 |
| Work month (round trips) | 43.3 times (10 × 4.33 weeks) | 181.86 |
| Work year (round trips) | 520 times (10 × 52 weeks) | 2,184.00 |
The work options assume five commuting days a week, all year. If you work from home some days or take holidays, use Work week (round trips) and scale the weekly figure by the weeks you really drive.
Fuel cost per mile and per 100 km
To get a cost per mile, enter 1 as the Distance with One way selected. At 25 MPG and 3.50 per gallon that is 0.14 a mile. In L/100 km, enter a Distance of 100 and the total is the cost of 100 km. The same trick works in km/L with a Distance of 1 for the cost per kilometer.
Using UK MPG or other gallon sizes
US (MPG) counts US gallons, and the price must be per US gallon. A UK imperial gallon is about 20% larger, so an MPG figure from a UK car or a UK road test is not the same number. Enter that car as L/100 km or km/L instead, or multiply the UK MPG by about 0.83 to get US MPG.
What the calculator leaves out
- No live fuel prices. You type the price, so use what you actually pay at the pump.
- No vehicle database. The efficiency is yours; real mileage varies with speed, load, weather and traffic.
- Fuel only. Tolls, parking, insurance, servicing and wear are not included.
- Your region's currency. The total is shown in the currency of your region, so enter the fuel price in that currency.
The result is an estimate from the numbers you enter. For a long drive, round the fuel needed up before you set off.
Other tools for trips and costs
To split the cost of a shared drive between passengers, use the Fair Bill Splitter. For converting miles, kilometers, gallons and liters on their own, there is the Measurement Converter, and the Gasoline Equivalent Calculator compares other fuels with gasoline.
Fuel cost calculator questions
How do I calculate fuel cost for a trip?
Divide the distance by your miles per gallon to get the gallons used, then multiply by the price per gallon. A 30 mile trip at 25 MPG uses 1.2 gallons, and at 3.50 per gallon that costs 4.20. The calculator does this as you type: enter Distance, Fuel efficiency and Fuel price, and the Total fuel cost appears.
How do I calculate fuel cost with L/100 km?
Divide the distance in kilometers by 100, multiply by the liters used per 100 km, then multiply by the price per liter. A 50 km trip at 7.8 L/100 km uses 3.9 liters, and at 1.85 per liter that costs 7.22. Choose L/100 km under Unit system and the fields switch to kilometers, liters and price per liter.
How much does it cost to drive to work?
Enter the one-way distance to work, then choose Work week (round trips), Work month (round trips) or Work year (round trips) under Frequency. For a 30 mile commute at 25 MPG and 3.50 per gallon, fuel costs 42.00 a week and 2,184.00 a year. Only fuel is counted, not tolls, parking or wear.
How much gas do I need for a trip?
Read Fuel needed under the total. It shows the gallons (US) or liters for the whole Frequency you picked, to one decimal place. A 30 mile one-way trip at 25 MPG needs 1.2 gal, a round trip needs 2.4 gal. Add a margin if the route has hills, heavy traffic or a full load.
Can I use UK MPG in this calculator?
Not directly. US (MPG) counts US gallons, and a UK imperial gallon is about 20% larger, so a UK MPG figure looks better than the same car's US MPG. Enter your consumption as L/100 km or km/L instead, or multiply the UK figure by about 0.83 to get US MPG.
How is the work month and work year fuel cost worked out?
Work week counts your distance 10 times, 5 days there and back. Work month multiplies that by 4.33 weeks, so 43.3 times. Work year multiplies it by 52 weeks, so 520 times. The line under Frequency shows how many times your distance is counted, which makes holidays easy to adjust for.
Does the calculator include tolls, parking or live gas prices?
No. It counts fuel only, from the price you type. It does not look up current gas prices, a car model or the route, and it does not add tolls, parking or wear and tear. Add those separately if you want the full cost of the drive.
Are my distance and price saved or sent anywhere?
No. Every figure is calculated on your device and nothing is uploaded. The calculator only remembers the efficiency value for each unit system while you use it, so switching between MPG, L/100 km and km/L does not wipe the other fields.
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