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Fuel Cost Calculator

With distance 300 mi, vehicle mileage 28 mpg, price per gallon 3.45 usd, fuel cost comes to $36.96 — fuel for the trip. It is reached in 4 steps, the last of which is gallons * price, and each one is printed on the page with its numbers filled in. The formula is the one published by US Department of Energy, not an approximation fitted to it.

What a trip costs in fuel, from its distance, the mileage the vehicle really gets and the pump price — with the cost per mile to compare on.

By Alex Seote, Built and maintains Rule Calculator · Formula and sources checked · How we check

Distance 300 mi, Vehicle mileage 28 mpg, Price per gallon 3.45

$36.96

Fuel for the trip for the example below. Editing a field recomputes the calculator below; this figure holds the answer the page was loaded with.

It is written into the HTML rather than drawn by a script, so a search engine reading this page without running JavaScript still finds an answer.

Fuel for the trip
$36.96
Fuel used
distance / mpg10.714 gal
Fuel for the trip
gallons * price36.964
Cost per mile
cost / distance0.123
Cost per 100 miles
per_mile * 10012.321

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Worked example

Three hundred miles at 28 mpg burns 10.71 gallons, so $36.96 at $3.45 a gallon — 12.3 cents a mile. The same trip in a vehicle getting 18 mpg costs $57.50, and that $20 gap is the whole argument for checking mileage rather than assuming it.

How to work it out yourself

  1. 1.Enter the distance you will actually drive, not the straight-line distance between the two places.
  2. 2.Use the mileage the vehicle really returns. Dividing the miles on a tank by the gallons it took to fill is more accurate than the sticker, and the gap between them is often 10-15%.
  3. 3.The cost per mile is the number worth keeping: it lets you compare a trip against a flight, a rental, or a different vehicle without redoing the arithmetic.

The formula

  1. Fuel useddistance / mpg
  2. Fuel for the tripgallons * price
  3. Cost per milecost / distance
  4. Cost per 100 milesper_mile * 100

Source: US Department of Energy — fueleconomy.gov, Where the Energy Goes: Gasoline Vehicles

Questions people actually ask

Why is my real mileage worse than the EPA figure?
The EPA figures come from a standard test cycle, and the things that hurt mileage most are not in it: cold starts, short trips, roof boxes, low tyre pressure, and speeds above about 55 mph, where aerodynamic drag rises with the square of speed. A 10-15% shortfall against the sticker is ordinary.
Does driving faster cost more?
Sharply, above about 50 mph. Air resistance rises with the square of speed, so the fuel to push through it rises steeply: the same trip at 75 mph rather than 65 typically costs 10-15% more and saves a few minutes an hour.
Should I use the round trip distance?
If that is what you are driving, yes — enter it directly. The cost per mile is the same either way, which is why it is the figure to compare on; the trip total is not comparable between a one-way and a return.

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