How to use Fuel Cost / Trip Cost Calculator
The fuel cost calculator estimates the petrol or diesel cost of any trip or your annual driving spend. Enter your route distance, vehicle fuel economy and local fuel price to get the trip cost instantly, then compare two vehicles side by side to see the annual savings from a more efficient model.
- Enter the trip distance (miles or km).
- Enter your vehicle's fuel economy (MPG or L/100km).
- Enter the current fuel price per gallon or per litre.
- Optionally compare a second vehicle.
- Review trip cost, annual cost and potential savings.
Your data never leaves your device — 100% private processing.
How fuel cost is calculated
Fuel cost = (Distance ÷ MPG) × Price per gallon. For metric: cost = (Distance × L/100km / 100) × Price per litre. Annual cost assumes you drive the same distance year-round at the same rate. The comparison shows annual savings — over 5 years, even modest MPG improvements compound into significant totals.
| MPG | Gallons/year | Annual fuel cost |
|---|---|---|
| 20 mpg | 750 | $2,625 |
| 25 mpg | 600 | $2,100 |
| 30 mpg | 500 | $1,750 |
| 35 mpg | 429 | $1,500 |
| 45 mpg (hybrid) | 333 | $1,167 |
Factors that affect real-world fuel economy
EPA ratings are achieved on standardised drive cycles; real-world MPG typically falls 10–20% below the label. Aggressive acceleration and braking, high speeds (drag increases with speed squared), cold weather, under-inflated tyres, heavy loads and roof boxes all reduce fuel economy. Highway driving is usually more efficient than city driving for non-hybrid vehicles.
Worked examples
1,200 miles/month at 28 MPG
Inputs: (1,200 ÷ 28) × $3.50
Result: ≈ $150/month fuel cost
1,200-mile road trip at 30 MPG
Inputs: (1,200 ÷ 30) × $3.50
Result: ≈ $140 in fuel
Trade 22-MPG truck for 34-MPG sedan
Inputs: 15,000 mi/yr at $3.50: 682 vs 441 gallons
Result: ≈ $2,386 vs $1,544 — save ~$842/yr
Glossary
- MPG
- Miles per gallon — the distance a vehicle travels on one gallon of fuel.
- L/100km
- Litres per 100 kilometres — the metric fuel economy standard; lower is better.
- EPA rating
- US Environmental Protection Agency's standardised fuel economy estimate.
- Drag coefficient
- A measure of aerodynamic resistance; affects fuel consumption significantly at highway speeds.
Related reading
Frequently Asked Questions
Why use Fuel Cost / Trip Cost Calculator?
- Calculates exact trip fuel spend from your vehicle's real-world MPG and the current pump price
- Compares annual fuel costs between two vehicles to quantify the dollar savings from switching models
- Supports both US gallons and metric litres for domestic trips and international road travel
- Projects multi-year fuel spend so the cost premium of a more efficient vehicle can be directly weighed
Common use cases
- Estimate petrol cost for a 1,200-mile road trip before finalising your travel budget
- Calculate how much you would save annually by trading a 22-MPG truck for a 34-MPG sedan
- Compare fuel spend for a hybrid versus a conventional SUV over the same 15,000 annual miles
- Work out per-kilometre fuel cost for an overseas rental car using local litre pricing
- Determine whether a longer motorway route actually costs more in fuel than a shorter congested road
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