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Road Trip Fuel Cost

TravelRoad Trips and Distance
Trip
Units

Miles in US mode, kilometres in metric mode.

Car and fuel

Miles per US gallon in US mode, litres per 100 km in metric mode.

Price per US gallon, or per litre in metric mode.

Fuel cost for the trip —
Fuel needed
—
Fuel unit
—
Cost per person
—
Cost per mile or km
—
Distance driven
—

A road trip's fuel cost is the distance divided by your car's fuel economy, times the pump price. A 300-mile drive in a 25 mpg car burns 12 gallons, so at $3.50 a gallon the fuel costs $42.00. Tick round trip to double the distance, and set the number of people to see each share.

About this tool

Planning a long drive usually starts with one question: how much will the gas cost? This calculator answers it for a one-way or return drive, in miles and mpg or in kilometres and litres per 100 km. It also divides the bill between passengers, which is handy when friends chip in, and reports the cost per mile or kilometre so you can compare driving against a train or bus fare. Enter the price you expect to pay at the pump; the currency symbol is only a label, so euro or pound prices work the same way. The result assumes a steady average economy. Mountain passes, a loaded roof box, heavy air-conditioning use or long stretches above 70 mph can push real consumption 10 to 20 percent higher than the rated figure.

How to use it

  1. Pick the units

    Choose US for miles, mpg and gallons, or Metric for kilometres, L/100 km and litres.

  2. Enter the one-way distance

    Type the route length from your map app, and tick Round trip if you are driving back the same way.

  3. Add the car and the fuel price

    Enter the fuel economy and the price per gallon or litre you expect along the route.

  4. Split the bill

    Use the − and + buttons to set how many people share the fuel cost; the per-person figure updates.

Examples

300 miles at 25 mpg, $3.50/gal

Units
US (mi, mpg, gal)
One-way distance
300
Round trip (drive back too)
No
People sharing the cost
1
Fuel economy
25
Fuel price per unit
3.5

Result Fuel cost for the trip: $42.00
Fuel needed: 12
Fuel unit: US gallons
Cost per person: $42.00
Cost per mile or km: $0.140
Distance driven: 300

  1. Total distance = 300 mi × 1 = 300 mi
  2. Fuel = 300 ÷ 25 mpg = 12 gal
  3. Cost = 12 gal × 3.5 = 42

Twelve gallons cover the drive one way, so the fuel bill is $42.00 for a single driver.

500 km each way, 6.5 L/100 km, two people

Units
Metric (km, L/100 km)
One-way distance
500
Round trip (drive back too)
Yes
People sharing the cost
2
Fuel economy
6.5
Fuel price per unit
1.8

Result Fuel cost for the trip: $117.00
Fuel needed: 65
Fuel unit: litres
Cost per person: $58.50
Cost per mile or km: $0.117
Distance driven: 1,000

  1. Total distance = 500 km × 2 = 1000 km
  2. Fuel = 1000 × 6.5 ÷ 100 = 65 L
  3. Cost = 65 L × 1.8 = 117
  4. Per person = 117 ÷ 2 = 58.5

1,000 km at 6.5 L/100 km burns 65 litres; at 1.80 per litre that is 117.00, or 58.50 each.

450 miles each way, 4 friends

Units
US (mi, mpg, gal)
One-way distance
450
Round trip (drive back too)
Yes
People sharing the cost
4
Fuel economy
30
Fuel price per unit
3.2

Result Fuel cost for the trip: $96.00
Fuel needed: 30
Fuel unit: US gallons
Cost per person: $24.00
Cost per mile or km: $0.107
Distance driven: 900

  1. Total distance = 450 mi × 2 = 900 mi
  2. Fuel = 900 ÷ 30 mpg = 30 gal
  3. Cost = 30 gal × 3.2 = 96
  4. Per person = 96 ÷ 4 = 24

900 miles at 30 mpg uses 30 gallons, $96.00 in total and $24.00 per person at $3.20 a gallon.

How it is calculated

Cost = D ÷ E × P (US); Cost = D × E ÷ 100 × P (metric)

D
Distance driven, one-way or doubled for a round trip
E
Fuel economy: miles per US gallon, or litres per 100 km
P
Fuel price per gallon or per litre

The fuel used is the distance over the economy in mpg, or the distance times the L/100 km figure divided by 100. Multiplying the fuel by the price gives the bill. The per-person share divides that bill by the number of people, and the cost per mile or km divides it by the distance driven. No tolls, parking or wear costs are included.

When not to use it

  • For electric cars, which are priced per kWh rather than per gallon or litre.
  • For a full trip budget that has to include tolls, parking or lodging.

Common mistakes

  • Entering the round-trip distance and also ticking Round trip, which doubles it twice.
  • Using the city mpg figure for a mostly highway drive, which overstates the cost.
  • Mixing UK gallons with US mpg; a UK gallon is about 20 percent larger.

Frequently asked questions

Which fuel economy figure fits a road trip?

For mostly interstate or motorway driving, the highway rating is closer to reality than the combined one. If you track your own fill-ups, your measured average beats any sticker figure, because it already reflects your speed, load and climate.

How do I convert L/100 km to mpg?

Divide 235.2 by the L/100 km figure to get US mpg. A car using 6.5 L/100 km returns about 36 US mpg. You do not need to convert here, though: switch the units to Metric and enter L/100 km directly.

Does a full car use more fuel?

Yes, but less than many people expect. An extra 100 lb of passengers or luggage typically cuts economy by around 1 percent in a mid-size car. A roof cargo box adds drag and can cost far more at highway speed, sometimes 10 percent or worse.

How much does speed change the fuel bill?

Above about 50 mph, aerodynamic drag rises quickly. US Department of Energy guidance puts each 5 mph over 50 at roughly the cost of an extra 30 cents per gallon or more. Cruising at 65 instead of 75 on a 300-mile leg can trim several dollars.

Can I use this with euros or pounds?

Yes. The dollar sign is only a label on the price field. Enter the price per litre in euros or pounds with the Metric units selected, and read the result in that same currency.

Why is the per-mile cost useful?

It lets you compare driving with other options. If the trip costs $0.14 per mile in fuel and a bus ticket for the same 300 miles is $60, driving alone is cheaper on fuel, before tolls, parking and wear are counted.

Cite this tool

Using this tool in an assignment, article or report? Copy a citation, or a link for your website.

APA

Tools Directory Editorial Team. (2026, October 14). Road Trip Fuel Cost. Tools Directory. Retrieved October 26, 2026, from https://tools.milunir.com/travel/road-trips-and-distance/road-trip-fuel-cost/

MLA

Tools Directory Editorial Team. “Road Trip Fuel Cost.” Tools Directory, 14 Oct. 2026, https://tools.milunir.com/travel/road-trips-and-distance/road-trip-fuel-cost/. Accessed 26 Oct. 2026.

Chicago

Tools Directory Editorial Team. “Road Trip Fuel Cost.” Tools Directory. Last modified October 14, 2026. Accessed October 26, 2026. https://tools.milunir.com/travel/road-trips-and-distance/road-trip-fuel-cost/.

Link<a href="https://tools.milunir.com/travel/road-trips-and-distance/road-trip-fuel-cost/">Road Trip Fuel Cost – Tools Directory</a>