Gas Calculator

Enter your vehicle’s gas mileage, cost of fuel, and distance driven to calculate your gas cost per month or for a trip. Plus, get an estimate of the amount of fuel you’ll consume.

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Monthly Fuel CostTrip Fuel Cost

Fuel Efficiency

mpgmpg (UK)L/100kmkm/L

Fuel Cost

$per gallonper liter

Daily Driving Distance

mileskilometers

Fuel Efficiency

mpgmpg (UK)L/100kmkm/L

Fuel Cost

$per gallonper liter

Trip Distance

mileskilometers

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Results: Estimated Monthly Fuel Cost

Results: Estimated Monthly Fuel Cost

$120.13

Estimated Fuel Used:

38.75 gallons 146.7 liters

Fuel Used gallons liters

Results: Estimated Trip Fuel Cost

$

Estimated Fuel Used:

- gallons - liters

Fuel Used gallons liters

Learn how we calculate this below

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By

Joe Sexton

Joe is the creator of Inch Calculator and has over 20 years of experience in engineering and construction. He holds several degrees and certifications.

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Reviewed by

Stephen Fogel

Stephen specializes in all aspects of the automotive world and has been an automotive enthusiast since childhood. He follows the global automotive industry closely, with an eye on the latest vehicle technologies.

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Sexton, J. (n.d.). Gas Calculator. Inch Calculator. Retrieved April 27, 2026, from https://www.inchcalculator.com/fuel-cost-calculator/

How to Calculate the Cost of Gas

With surging gas prices, understanding how much you spend on fuel can help you budget more effectively. Calculating your monthly gas cost is straightforward once you know your driving habits, fuel efficiency, and current gas prices.

By following a few simple steps, you can estimate how much you’ll spend on gas.

Step One: Determine How Many Miles You Drive Each Month

Start by estimating how many miles you drive in a typical month. You can find this by looking at your daily commute and regular errands.

For example, if you drive 30 miles per day and drive about 22 days per month, your monthly mileage looks like this:

30 × 22 = 660 miles per month

If your driving varies, you can check your odometer at the beginning and end of the month or review trip data from your vehicle or a navigation app to get a more accurate average.

Step Two: Find Your Vehicle’s Miles Per Gallon (MPG)

Next, determine your vehicle’s fuel efficiency, usually listed as miles per gallon (MPG). You can find this in your owner’s manual, on the manufacturer’s website, by checking fuel economy estimates online,^[1] or by using a gas mileage calculator.

For example, if your car gets 25 MPG, it means you can drive 25 miles on one gallon of gas.

Step Three: Calculate Gallons of Gas Used Per Month

Divide your monthly miles by your vehicle’s MPG to find out how many gallons of gas you use.

660 miles ÷ 25 MPG = 26.4 gallons per month

This tells you how much fuel your vehicle consumes each month based on your driving distance.

Step Four: Multiply by the Price of Gas

Finally, multiply the number of gallons you use by the average price of gas in your area. The cost of gas varies by region and is affected by volatility in the energy markets. While gas prices were $3.10 per gallon in 2025,^[2] which are generally lower than historical averages, they have been surging in 2026 due to the Iran conflict.

26.4 gallons × $3.20 per gallon = $84.48 per month

This is your estimated monthly gas cost.

Gas Cost Formula

This calculation can be broken down into a simple gas cost formula:

monthly gas cost = (miles driven per month ÷ MPG) × price per gallon

So, your monthly gas cost is equal to the average miles driven per month divided by your vehicle’s fuel efficiency in miles per gallon, multiplied by the price of gas per gallon.

You might be interested in our fuel savings calculator.

How to Calculate Trip Fuel Costs

To estimate the amount of fuel used for a trip and to find the cost of that fuel, follow these simple steps.

Step One: Determine Trip Distance

Start by estimating the driving distance for the trip. Try Google Maps to find your trip distance.

Step Two: Determine Your Vehicle Fuel Economy

Then, find the estimated fuel efficiency of your vehicle following the same steps as above.

Step Three: Determine the Price of Gas

Next, check the price per gallon of the gasoline that you are using, which will be needed to calculate the cost of the trip. Note that you’ll want to check the price of gas where you’ll be traveling, since it can vary by region and state.

Step Four: Use the Trip Gas Cost Formula

Finally, enter those values into these formulas to calculate the amount of fuel used and to determine the cost of that fuel:

fuel used = distance ÷ fuel efficiency
fuel cost = fuel used × cost per gallon

Be sure that your fuel economy units are the same as the units of fuel being purchased (MPG and gallons of fuel). For metric fuel consumption, try our liters per 100 km to km per liter conversion calculator to find the fuel economy value to use in these formulas.