How do I calculate gas cost for a trip?

Miles ÷ mpg × price per gallon. 300 miles at 30 mpg is 10 gallons; at {{$3.50}} a gallon, {{$35}}.

How much gas will I use driving 500 miles?

500 ÷ your mpg. At 25 mpg it is 20 gallons; at 40 mpg, 12.5.

Should I count the drive back?

If you are coming back, yes — choose 'round trip' and the distance is doubled.

How do I split gas money with passengers?

Divide the trip's fuel cost by the number of people sharing it. Set 'people sharing the cost' and the page shows each share.

How do I convert L/100 km to mpg?

Divide 235.215 by the L/100 km figure for US mpg: 7 L/100 km is 33.6 mpg. The same number works the other way, so 30 mpg is 7.84 L/100 km. For UK (imperial) gallons, use 282.48 instead.

Does driving faster use more fuel?

Yes. fueleconomy.gov says gas mileage usually drops quickly above 50 mph, and each 5 mph over 50 lowers it by about 7%. On a long trip, dropping from 75 to 65 mph can save more fuel than a cheaper station would.

How do I find my car's real fuel economy?

Fill the tank, reset the trip meter, drive normally, then fill up again: the miles driven divided by the gallons it took to refill is your mpg. Over two or three tanks the figure settles, and it is the one to use here.

Gas Cost Calculator for a Trip (Fuel Cost, Round Trip, Split)

Fuel and cost for a road trip, one way or round trip, split between passengers, in miles or km.

Inputs

Trip distance(km)

0.1 km50,000 km

Fuel efficiency(km/L)

0.1 km/L50 km/L

Fuel price(/L)

0 /L500 /L

Trip

People sharing the cost

120

Units

Include CalculateEveryday mark

Round-trip fuel cost

42.93

Working: 700 km ÷ 15 km/L = 46.67 L × 0.92 a litre = 42.93
Each person's share: 21.47 (2 people)
Fuel needed: 46.67 L
Cost per km: 0.06
Distance: 350 km
Efficiency: 15 km/L

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What each Gas Cost for a Trip input means

Trip distance: One-way distance in kilometres or miles, from a map app. Choose 'round trip' below rather than doubling it yourself.
Fuel efficiency: Your car's fuel economy in km/L, or mpg in US units. The figure from your own fill-ups beats the window sticker; highway driving usually gets more than the combined rating, and towns less.
Fuel price: What you pay per litre, or per gallon in US units. Use the price where you will fill up; prices along a motorway are often higher than in town.
Trip: One way or there and back. A round trip doubles the distance and the fuel.
People sharing the cost: How many people are sharing the fuel cost, driver included. Set to 1 for the whole cost.
Units: Metric (km, km/L, price per litre) or US (miles, mpg, price per gallon). Switching converts the numbers already entered.

Gas Cost for a Trip formula

fuel = distance ÷ economy (mpg or km/L) · cost = fuel × price · each = cost ÷ people

\text{cost} = \frac{d}{e} \times p

Divide the distance by the car's fuel economy to get the fuel the trip burns — miles ÷ mpg gives gallons, kilometres ÷ km/L gives litres — and multiply by the price you pay at the pump. A round trip doubles the distance; sharing the car divides the cost. The page shows the working, the cost per mile or kilometre, and each passenger's share. Use the economy your car actually gets on the road you will drive: highway figures beat city ones, and a loaded car, roof box or headwind uses more.

Gas Cost for a Trip worked example

A 350 km drive there and back is 700 km; at 15 km/L that is 46.67 litres, and at $0.92 a litre $42.93, or $21.47 each for two. In US terms, 220 miles each way at 35 mpg and $3.50 a gallon is 440 ÷ 35 = 12.57 gallons, $44, or $14.67 each for three.

More Gas Cost for a Trip examples

A 220-mile drive each way at 35 mpg, gas at $3.50 a gallon, three people sharing: 440 ÷ 35 = 12.57 gallons, and 12.57 × 3.50 = 44.00 for the round trip — $14.67 each.

500 miles one way in an SUV that gets 25 mpg: 500 ÷ 25 = 20 gallons, and at $3.15 a gallon that is 20 × 3.15 = 63.00, about $0.13 a mile.

Where the Gas Cost for a Trip calculator can give the wrong answer

The price is what you type. Fuel prices change by the week and by the station, so budget with a little extra.
Real economy is usually below the label, especially in traffic, at high speed, with air conditioning or a heavy load.
Tolls, parking and wear on the car are not fuel and are not included.
For an electric car, use the cost per kWh and kWh per mile instead; this page is for fuel.

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Gas Cost for a Trip reference table

Fuel used over 100 miles at different fuel economies, and its cost at 3.50 a gallon
Fuel economy (mpg, US)	Gallons per 100 miles	Litres per 100 km	Cost per 100 miles at 3.50 a gallon
15	6.67	15.68	23.33
20	5.00	11.76	17.50
25	4.00	9.41	14.00
30	3.33	7.84	11.67
35	2.86	6.72	10.00
40	2.50	5.88	8.75
50	2.00	4.70	7.00

Source: Arithmetic: 100 ÷ mpg; L/100 km = 235.215 ÷ mpg, from 1 US gallon = 3.785411784 L and 1 mile = 1.609344 km (NIST)

Gas Cost for a Trip FAQ

: Miles ÷ mpg × price per gallon. 300 miles at 30 mpg is 10 gallons; at {{$3.50}} a gallon, {{$35}}.
: 500 ÷ your mpg. At 25 mpg it is 20 gallons; at 40 mpg, 12.5.
: If you are coming back, yes — choose 'round trip' and the distance is doubled.
: Divide the trip's fuel cost by the number of people sharing it. Set 'people sharing the cost' and the page shows each share.
: Divide 235.215 by the L/100 km figure for US mpg: 7 L/100 km is 33.6 mpg. The same number works the other way, so 30 mpg is 7.84 L/100 km. For UK (imperial) gallons, use 282.48 instead.
: Yes. fueleconomy.gov says gas mileage usually drops quickly above 50 mph, and each 5 mph over 50 lowers it by about 7%. On a long trip, dropping from 75 to 65 mph can save more fuel than a cheaper station would.
: Fill the tank, reset the trip meter, drive normally, then fill up again: the miles driven divided by the gallons it took to refill is your mpg. Over two or three tanks the figure settles, and it is the one to use here.