How to Calculate Fuel Cost
Fuel expenses represent one of the largest ongoing operational costs of vehicle ownership. Calculating your cost per mile and trip costs enables accurate tax deductions, road trip cost sharing, and smart commuter budgeting.
Divide distance by MPG to find gallons needed, then multiply by the local gas price.
How to Calculate Fuel Cost Per Mile
Calculating cost per mile tells you exactly how much every mile of driving costs in gasoline alone.
Formula: Cost Per Mile = Price Per Gallon ÷ Vehicle MPG.
Example: With gasoline at $3.50 per gallon and a car that achieves 28 MPG: $3.50 ÷ 28 = $0.125 per mile (12.5 cents).
If you drive 12,000 miles per year, your annual fuel budget is: 12,000 × $0.125 = $1,500.00.
How to Calculate Fuel Cost Per Kilometer
For metric calculations with fuel priced in liters:
Formula: Cost Per Kilometer = (L/100km ÷ 100) × Price Per Liter.
Example: If your car consumes 7.5 L/100km and petrol costs $1.60 per liter: (7.5 ÷ 100) × 1.60 = 0.075 × $1.60 = $0.12 per kilometer.
Calculating Round-Trip and Multi-Stop Trips
When budgeting for road trips, always factor in local destination driving (city driving while exploring your destination) which typically adds 10% to 20% more mileage than direct highway navigation distances.
Additionally, fuel prices vary drastically between states and highway rest stops. Planning fuel stops in low-tax jurisdictions can save $0.40 to $0.80 per gallon.
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Use our free, client-side calculator to compute instant MPG, L/100km, fuel expenses, and conversion metrics.
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