Fuel Cost Calculator

Calculate the fuel cost of any trip given distance, fuel efficiency (MPG), and fuel price per litre. Useful for budgeting long journeys, comparing transport options, or tracking cost per mile.

300-mile round trip at 40 MPG with 1.50/litre petrol: needs 34 litres at 51 total - 17p/mile. Compare to rail at 45-80 or EV charging at 12-20 for the same trip. Numbers reframe transport decisions.

The tool uses gallons (4.546 litres) - the standard for MPG figures. gallons are 3.785 litres - adjust accordingly if using MPG.

Quick example

With distance of 300 and mpg of 40 (plus fuel price per litre of 1.5), the result is 51.14. Change any figure and watch the output shift — it's often more useful to see the pattern than to memorise the formula.

Which inputs matter most

You enter Distance (Miles), MPG Gallons), and Fuel Price per Litre.

What's happening under the hood

Litres needed = (distance × 4.546) / MPG. Cost = litres × price per litre. Uses gallon conversion (1 gallon = 4.546 litres). The formula is listed in full below. If the number looks off, you can retrace the calculation by hand — that's the point of showing the working.

What the bill doesn't show

Standing charges, discounts, and usage tiers all blur the effective rate. The calculation here backs out the total so you're comparing apples to apples across providers, regardless of how each one packages the price.

What this doesn't capture

Usage varies month-to-month; tariffs change; discounts come and go. The figure here is a clean baseline — your actual annual bill will fluctuate around it. Use the calculation to benchmark providers, not as a prediction of a specific bill.

Worked example

Suppose you plan a 450-mile journey in a vehicle that returns 35 MPG, and local fuel costs 1.65 per litre.

1. Distance: 450 miles
2. Fuel needed: (450 × 4.546) ÷ 35 = 58.6 litres
3. Total cost: 58.6 × 1.65 = 96.69
4. Cost per mile: 96.69 ÷ 450 = 0.215 per mile

This breakdown shows both the absolute trip cost and the per-mile rate, making it easier to compare with alternative journeys or transport modes.

When this calculation matters

The calculator is most useful when planning longer trips where fuel represents a meaningful budget item. Common scenarios include:

• Comparing the fuel cost of different routes or vehicle choices
• Budgeting for regular commutes or business mileage
• Understanding how fuel price changes affect journey economics
• Evaluating cost per mile to track vehicle operating efficiency
• Planning multi-leg trips and allocating fuel budgets

What this shows and what it doesn't

Included

The calculator produces three outputs: total fuel cost for the specified distance, litres of fuel consumed, and cost per mile driven. It applies standard volume conversions and uses the fuel efficiency and price figures you provide.

Not included

The calculation does not account for variations in real-world MPG (which fluctuates with driving style, traffic, terrain, and weather), fuel price fluctuations during a journey, or any other operating costs such as maintenance, tolls, or parking. It models fuel expense in isolation and assumes consistent efficiency across the entire distance.

For illustration only

This calculator estimates fuel costs based on the inputs you supply. It is designed for educational comparison and trip budgeting. Actual costs will vary depending on driving conditions, vehicle maintenance, and prevailing fuel prices at the time of travel.