Gas Cost Calculator
Find out what a drive will cost in gas. Enter the distance, your car's fuel economy and the price of gas to see the total cost, the gallons you need and the cost per mile. It works in miles or kilometres and in MPG, L/100km or km/L, and results update as you type.
Gas cost = (miles ÷ MPG) × price per gallon. Miles ÷ MPG is the gallons you need. The calculator below opens on 300 miles at 30 MPG, which is 10 gallons, and 10 gallons at $3.50 a gallon costs $35.00, about $0.117 a mile.
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How much is a fill-up?
The price of an amount of gas, at the gas price you entered above.
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How to use the gas cost calculator
Type in three numbers and the cost appears as you type. There is no button to press, and nothing you enter is sent anywhere.
Trip distance. How far you are driving, in miles or kilometres. For a drive there and back, enter the one-way distance and tick Round trip, which doubles it.
Fuel economy. How far your car goes on a set amount of fuel. In the US that is miles per gallon (MPG). A new car shows its EPA rating on the window sticker, and you can look up a car's rating on fueleconomy.gov. Your own average from past fill-ups is usually closer to real life. If you think in litres per 100 km or km per litre, pick that unit and the calculator converts it for you.
Gas price. What you pay, per gallon or per litre. Prices change week to week and town to town, so the box starts with an example: type your local price. The U.S. Energy Information Administration publishes national and regional average gas prices every week.
Split between people. Carpooling? Tick Split the cost and enter how many people are chipping in to see each person's share.
Price of a fill-up. Type a number of gallons in the fill-up box to see what that much gas costs at your price.
Everything runs in your browser. The numbers you type are never uploaded.
Gas cost examples, worked out
The prices here are round example figures, not today's prices.
- One-way drive. 300 miles at 25 MPG uses 300 ÷ 25 = 12 gallons. At $3.50 a gallon that is 12 × $3.50 = $42.00, or $0.14 a mile.
- Round trip, split 2 ways. 120 miles each way is 240 miles. At 32 MPG that is 240 ÷ 32 = 7.5 gallons, and at $3.20 a gallon the trip costs $24.00, or $12.00 each.
- Metric. 500 km in a car that uses 8 L/100km burns 500 ÷ 100 × 8 = 40 litres. At $1.80 a litre that is $72.00, about $0.144 per km. (8 L/100km is about 29.4 US MPG.)
Gas cost per 100 miles
This table shows what 100 miles of driving costs. Find your car's MPG down the left and a gas price per gallon across the top; the prices are examples from $3.00 to $5.00. For another distance, scale it: 300 miles costs three times the figure shown.
| MPG | $3.00 | $3.50 | $4.00 | $4.50 | $5.00 |
|---|---|---|---|---|---|
| 15 MPG | $20.00 | $23.33 | $26.67 | $30.00 | $33.33 |
| 20 MPG | $15.00 | $17.50 | $20.00 | $22.50 | $25.00 |
| 25 MPG | $12.00 | $14.00 | $16.00 | $18.00 | $20.00 |
| 30 MPG | $10.00 | $11.67 | $13.33 | $15.00 | $16.67 |
| 35 MPG | $8.57 | $10.00 | $11.43 | $12.86 | $14.29 |
| 40 MPG | $7.50 | $8.75 | $10.00 | $11.25 | $12.50 |
| 50 MPG | $6.00 | $7.00 | $8.00 | $9.00 | $10.00 |
Common gas cost questions
How do I calculate the gas cost of a trip? Divide the miles by your car's MPG to get the gallons you need, then multiply the gallons by the price per gallon. For example, 300 miles at 25 MPG is 12 gallons, and at $3.50 a gallon that is $42.00. For a round trip, double the miles first.
How much is 25 gallons of gas? Multiply 25 by the price per gallon. At $3.00 a gallon, 25 gallons costs $75.00. At $3.50 it costs $87.50, and at $4.00 it costs $100.00. The fill-up box on this page works it out for any amount at your price.
How much does it cost to drive 100 miles? Divide 100 by your MPG to get the gallons, then multiply by the gas price. At 25 MPG and $3.50 a gallon, 100 miles takes 4 gallons and costs $14.00. The table on this page shows other combinations.
How do I convert L/100km to MPG? Divide 235.21 by the L/100km figure to get US miles per gallon. For example, 10 L/100km is about 23.5 MPG. You can also type L/100km or km/L straight into this calculator, or use the fuel economy calculator to convert between every unit.
What MPG should I use for my car? Your own average from past fill-ups is the most realistic figure. Otherwise use the EPA rating from the window sticker or fueleconomy.gov: the highway figure for a long highway drive, the combined figure for mixed driving. Higher speeds, hard acceleration, cold weather, short trips and heavy loads all lower real MPG.
This is a fuel-only estimate. It does not include tolls, parking or wear and tear. An all-electric car runs on electricity rather than gallons, so these figures do not apply to one.