Gas money calculator
Split the fuel cost of a trip between riders and the driver, with tolls added and each share rounded up to the cent.
Nothing you enter leaves this page.
Each person pays
$each
- Total to split
- $
Rounded up to the next cent, so the group covers the total.
How this is calculated
The fuel cost is either the total you type, or miles (doubled for a round trip) divided by mpg, times the gas price. Tolls are added to make the total to split. The total is rounded to the cent, divided by the number of people paying, and each share is rounded up to the next cent so the group never comes up short.
each share = (fuel + tolls) ÷ people paying, rounded up to the cent
The method, the constants and the limits are written out in how fuel cost is calculated.
How to split gas fairly
The simplest fair split counts the driver as one of the people paying, because the car is making the trip for everyone in it. Many groups do that and leave the car’s wear out of it. If the riders are covering the whole cost, untick the driver’s share and the total is split among the riders alone.
For a regular carpool you can work out the gas for one day and split that, or add up a week and split the week. Either way the share each person owes works the same, so pick whichever your group will actually settle. Remember tolls and parking: tolls can be added above, and parking you can add to the total yourself by using the total-cost mode.
Worked example: three people share a 200-mile drive
Example numbers: 200 miles at 30 mpg, gas at $3.50 a gallon, two riders and a driver who pays a share.
- Fuel: 200 ÷ 30 × $3.50 = $23.33.
- People paying: 2 riders + 1 driver = 3.
- $23.33 ÷ 3 = $7.777…, rounded up to $7.78 each.
Three payments of $7.78 come to $23.34, one cent more than the total. That cent is the rounding, and it is why the shares are rounded up rather than down.
About the rounding
Cash and payment apps work in whole cents. If the total does not divide evenly, someone has to pay a fraction of a cent. Rounding every share up by less than one cent keeps the arithmetic simple and makes sure the driver is not out of pocket. The difference is at most a cent per person.
To work out the fuel for a multi-stop route first, use the trip gas calculator, then enter its total here. For the plain trip cost with no split, use the fuel cost calculator, and for commuting by the month see the monthly fuel cost calculator.
Common questions
Should the driver pay a share?
That is for your group to decide. Counting the driver as one of the payers is a common starting point. Untick the box if the riders are covering the whole cost.
Why is each share rounded up?
So the shares always add up to at least the total. The extra is under one cent per person.
Can I split a total I already know?
Yes. Choose the total gas cost option, enter the amount, and the tolls and number of people work the same way.
Does it include wear on the car?
No. It splits fuel and any tolls you enter. Wear, insurance and parking are not included unless you add them to the total.