Fuel Cost Calculator
Work out exactly what a trip will cost in fuel. Enter your distance, your vehicle's fuel efficiency, and the price of fuel — and get the total gas/petrol cost, fuel needed, cost per mile or km, and the cost split between passengers. Works in miles or km, gallons or litres, any currency.
Enter your trip distance, fuel efficiency, and fuel price. Choose your units (miles/km, gallons/litres, MPG or L/100km), toggle a round trip, and optionally split the cost between passengers.
* Estimates assume steady fuel efficiency; real-world mileage varies with traffic, terrain, load, weather, driving style, and vehicle condition. Fuel prices change frequently and differ by region. Use the result as a planning estimate and check current local fuel prices before your trip.
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What Is a Fuel Cost Calculator?
A fuel cost calculator is a free online tool that estimates how much fuel a trip will use and what it will cost. You enter three things — the distance, your vehicle's fuel efficiency (MPG or L/100km), and the price of fuel — and it instantly returns the total cost, the amount of fuel needed, the cost per mile or kilometre, and (if you're sharing the ride) the cost per passenger.
Our fuel cost calculator is built to work anywhere. It accepts miles or kilometres, US gallons, imperial (UK) gallons, or litres, and efficiency measured as MPG, km per litre, or L/100km — so whether you drive in Texas, the UK, India, or Australia, the numbers come out right. You can also toggle a round trip and compare two vehicles side by side.
How to Use This Fuel Cost Calculator
- Pick your units — miles or kilometres, and your currency symbol.
- Enter the trip distance — one way, then toggle "round trip" if you're coming back.
- Enter your fuel efficiency — and choose how it's measured (MPG US/UK, km/L, or L/100km).
- Enter the fuel price — per gallon or per litre, whichever your station shows.
- Optional: split between passengers — and compare a second vehicle.
How to Calculate Fuel Cost (The Formula)
The underlying math is straightforward once everything is in matching units:
Total cost = Fuel needed × Price per unit
Cost per mile/km = Total cost ÷ Distance
Example (US units): a 300-mile trip in a car that does 30 MPG, with gas at $3.85/gallon. Fuel needed = 300 ÷ 30 = 10 gallons. Total cost = 10 × $3.85 = $38.50. Cost per mile = $38.50 ÷ 300 ≈ $0.128/mile.
Example (metric): a 300 km trip at 7 L/100km, fuel at $1.60/litre. Fuel needed = 300 ÷ 100 × 7 = 21 litres. Total cost = 21 × $1.60 = $33.60.
MPG vs L/100km vs km/L: Understanding Fuel Efficiency
Different countries measure efficiency differently, which trips up a lot of travelers:
- MPG (miles per gallon): used in the US and UK. Higher is better. Note US and UK gallons differ — a UK gallon is about 1.2 US gallons, so UK MPG figures look higher for the same car.
- L/100km (litres per 100 km): used across Europe, and common in Australia and Canada. Lower is better — it's fuel used, not distance covered.
- km/L (kilometres per litre): common in India, Japan, and parts of Asia. Higher is better.
Our calculator converts between all of these internally, so you can enter whatever your dashboard or manual shows.
How to Split Fuel Cost Between Passengers
Sharing a road trip? Splitting fuel fairly is simple: divide the total fuel cost by the number of people travelling. For a $60 fuel bill shared between 4 people, that's $15 each. Our calculator does this automatically when you set the "split between" field. For splitting other shared trip costs like meals, our Tip Calculator handles bills and gratuity between any number of people.
Tips to Lower Your Fuel Costs
- Keep tyres properly inflated — under-inflated tyres can cut efficiency by several percent.
- Slow down on highways — fuel use rises sharply above about 80 km/h (50 mph).
- Remove excess weight and roof racks — both increase consumption.
- Drive smoothly — hard acceleration and braking waste fuel; anticipate traffic.
- Combine trips — a warm engine is more efficient than several cold starts.
- Compare fuel prices — prices vary widely between stations; a few cents per litre adds up on a full tank.