How this calculator works
Distance ÷ economy = fuel used; × price = cost. Works in miles per gallon or km per litre as long as all three inputs use the same units.
- Fuel used = distance ÷ fuel economy (miles ÷ MPG, or km ÷ km per litre).
- Cost = fuel used × price per gallon (or litre).
- Per year = monthly × 12. Per week = monthly × 12 ÷ 52.
Worked example
With these inputs: miles (or km) driven per month 900; fuel economy 28; price per gallon $3.6.
The result is fuel per month $115.71, with per year $1,388.57 and per week $26.70.
Getting an accurate miles-per-month figure
Check your odometer on the same date two months in a row, or multiply a round-trip commute by working days (about 21–22 a month) and add a weekly allowance for errands. Use your car's real-world MPG from the dashboard display or from fill-up records, not the sticker figure.
Budget fuel like a bill
Fuel is a variable cost, but it's predictable enough to budget. Add the monthly figure as a recurring bill so it's set aside with everything else, and check it when gas prices move.
Frequently asked questions
How do I calculate my monthly gas cost?
Divide monthly miles by your MPG to get gallons, then multiply by the price per gallon. 900 miles at 28 MPG and $3.60 a gallon is about $116 a month.
How do I calculate the cost of a road trip?
Enter the trip's total distance as the miles figure. The "fuel per month" result is then the trip's fuel cost.
Does this work for electric cars?
Use the Electricity Cost Calculator instead, with the charger's power and charging hours.