Summary: Calculate Fuel Cost Free and Privately
A fuel cost calculator turns three numbers into a trip budget: the distance, your vehicle's fuel economy and the price of fuel. This free fuel cost calculator takes fuel economy as US MPG, UK MPG, L/100km or km/L, distance in miles or kilometres, and a price per US gallon or per litre. It returns the total cost, the fuel needed, and the cost per mile and per km.
The calculator runs in your browser; nothing is uploaded (you can check the Network tab in DevTools). Vehicles and trips you choose to save stay in your browser's local storage on this device.
The core formula is fuel needed = distance ÷ fuel economy, then cost = fuel needed × price. At 30 MPG, a 100-mile drive burns 3.33 US gallons, or $11.67 at $3.50 a gallon. Every combination is converted through litres, so mixing units gives the same answer as using one unit throughout. For other conversions, try the unit converter or the length converter.
Table of Use: Fuel Cost Examples
Results use the calculator's own formulas. Prices are illustrative, not current market prices.
| Scenario | Inputs | Fuel needed | Total cost |
|---|---|---|---|
| Short drive | 100 miles, 30 MPG (US), $3.50 per US gallon | 3.33 US gal | $11.67 |
| US road trip, round trip | 300 miles each way, 30 MPG (US), $3.50 per US gallon | 20.00 US gal | $70.00 |
| European journey | 500 km, 7 L/100km, €1.80 per litre | 35.00 L | €63.00 |
| UK drive | 120 miles, 45 MPG (UK), £1.50 per litre | 12.12 L | £18.18 |
| India highway | 450 km, 15 km/L, ₹100 per litre | 30.00 L | ₹3,000.00 |
Features
- Four fuel economy units. MPG (US), MPG (UK), L/100km and km/L, converted through litres (1 US gallon = 3.785411784 L, 1 UK gallon = 4.54609 L, 1 mile = 1.609344 km).
- Round trip. A checkbox doubles the one-way distance.
- Seven currency symbols. USD, EUR, GBP, INR, CAD, AUD and JPY. The symbol is a label only and nothing is converted, so enter the price in that currency. For exchange rates, use the currency converter.
- Full result panel. Total fuel cost, fuel needed (US gallons or litres, matching your price unit), total distance, and cost per mile and per km, plus a Copy Result button.
- Save Vehicle. Store a name with its fuel economy and unit, then click it to reload.
- Multiple Trip Planning. Add Current Trip saves a distance under a name, and All Trips Total adds every saved trip at the efficiency and price now entered.
- Compare Vehicle Efficiency. Show Comparison lists four editable fuel economy values for the same trip and price, with a Savings vs Current column.
- Input checks. Distance must be 0 to 1,000,000,000, fuel economy above 0 and price 0 or more.
A 300-mile one-way trip at $3.50 per US gallon costs:
| Fuel economy | Fuel needed | Cost | Cost per mile |
|---|---|---|---|
| 20 MPG | 15.00 US gal | $52.50 | $0.175 |
| 30 MPG | 10.00 US gal | $35.00 | $0.117 |
| 40 MPG | 7.50 US gal | $26.25 | $0.088 |
| 50 MPG | 6.00 US gal | $21.00 | $0.070 |
The result ignores tolls, parking, traffic and hills and uses one fuel economy figure for the whole distance, so treat it as a budget estimate.
How to Use the Fuel Cost Calculator
- Type the one-way trip length in Distance (one way) and choose Miles or Km. Tick Round trip if you are driving back.
- Enter Fuel Efficiency and pick MPG (US), MPG (UK), L/100km or km/L from the menu beside it.
- Under Fuel Price, choose a currency, type the pump price and pick / US gallon or / Liter.
- Read the Trip Cost panel and press Copy Result to keep the numbers.
- To reuse a car, type a name under Save Vehicle and press Save. To combine journeys, name the trip, press Add Current Trip, change the distance and add the next one.
- Open Show Comparison and edit the efficiency values to price the same trip in a different car.
For the journey time, use the speed calculator. For multi-day trips, the date difference calculator counts the days.
Who Can Use It
- Commuters who want a running fuel figure. Save the commute as a trip and read the cost per mile or per km.
- Road trippers and carpoolers who need a budget. Take the total to the split bill calculator so each passenger pays a share.
- Car shoppers comparing a thirsty vehicle with an efficient one, who can then weigh the purchase price in the loan calculator.
- Drivers abroad who meet MPG at home and L/100km on the road. The percentage calculator shows what a price rise adds, and the discount calculator handles a cents-off voucher.
No mileage-reimbursement rate or tax rule is applied, so use your employer's or tax authority's rate for business claims.
FAQs
How do I calculate the fuel cost of a trip?
Divide the distance by your fuel economy to get the fuel needed, then multiply by the price per unit. A car doing 30 MPG over 300 miles needs 10 US gallons, which is $35 at $3.50 a gallon, or $70 for the round trip. With L/100km, fuel needed is distance in km multiplied by L/100km, divided by 100.
What is the difference between US MPG and UK MPG?
A US gallon is 3.785 litres and a UK (imperial) gallon is 4.546 litres, so the same car shows a higher MPG figure in the UK. 30 US MPG is about 36 UK MPG. Choose the MPG type that matches where your figure came from. The calculator converts through litres, so UK MPG with a price per litre works correctly.
How do I convert MPG to L/100km?
Divide 235.215 by US MPG, or 282.481 by UK MPG, to get litres per 100 km. For example, 30 US MPG is about 7.84 L/100km. Lower L/100km means better efficiency, the opposite of MPG. To get km/L from L/100km, divide 100 by the L/100km figure. You can type either unit into the calculator.
Can I enter the fuel price in euros, pounds or rupees?
Yes. The currency menu offers USD, EUR, GBP, INR, CAD, AUD and JPY. It only sets the symbol shown in the results and does not convert anything, so type the pump price in that same currency. The price can be per US gallon or per litre. There is no per-UK-gallon option, so use the litre price for UK trips.
Are my saved vehicles and trips uploaded anywhere?
No. The calculator runs in your browser and nothing is uploaded; you can check the Network tab in DevTools. Saved vehicles and trips are stored in your browser's local storage on this device only, so they are not shared across devices. Clearing your browser data, or using private browsing, removes them.
How do I find my car's real fuel economy?
Fill the tank, reset the trip meter, drive as normal, then fill up again. Divide the distance by the fuel added for MPG or km/L, or divide the fuel by the distance and multiply by 100 for L/100km. A measured average usually beats the official rating, because speed, traffic and load change real consumption.
More free tools are on the calculators hub.