Sharing a ride is one of the cheapest ways to travel, but it only stays friendly if everyone agrees on what a fair split looks like. The driver would have bought the gas anyway, passengers are using the seat, and the car wears out a little with every mile. This gas split calculator works out the cost of the trip from distance, mpg and gas price, adds optional wear and tear and tolls, and divides it among the people in the car — with or without the driver paying a share.
How to use the gas split calculator
- Enter the trip distance (one way or round trip, as you will be paying for it).
- Enter the car's mpg and the gas price.
- Enter how many people are in the car, including the driver, and whether the driver pays a share.
- Add wear and tear per mile and tolls if your group wants to include them.
- Read the total and the amount each paying person owes.
For a full trip budget with food and parking see the trip cost calculator; to find your car's mpg, the gas mileage calculator; for work travel, the mileage reimbursement calculator.
Gas split formula
Total = fuel cost + wear and tear per mile × distance + tolls
Cost per person = total ÷ number of paying people
- Paying people = everyone in the car, or everyone but the driver
- Wear and tear is optional; leave it at 0 to share only fuel and tolls
Worked example: four people, 300 miles
- Fuel: 300 ÷ 25 × $3.50 = $42.
- Wear and tear at $0.10 a mile: 300 × 0.10 = $30.
- Total: $72.
- Shared by four people: $18 each, or $0.06 per person per mile.
How the group size changes the share
A 300-mile trip in a 25-mpg car at $3.50 a gallon, fuel only. Each value is calculated with the formula above.
| People sharing | Fuel cost | Cost per person | Per person per mile |
|---|---|---|---|
| 1 | $42.00 | $42.00 | $0.140 |
| 2 | $42.00 | $21.00 | $0.070 |
| 3 | $42.00 | $14.00 | $0.047 |
| 4 | $42.00 | $10.50 | $0.035 |
| 5 | $42.00 | $8.40 | $0.028 |
Making the split fair
The simplest rule is to share the fuel and tolls equally. That is fair when everyone gets the same benefit, and it is easy to calculate. A per-mile allowance for wear and tear makes it fairer to the car's owner, who is also paying for tires, services and depreciation. The IRS standard business mileage rate, for example, is 76 cents per mile for the second half of 2026 because it includes all of a car's operating costs; a small fraction of it is a common compromise for a carpool.
The driver question depends on the arrangement. A regular carpool, where people take turns driving, usually splits costs equally including the driver. If one person drives for others as a favour, passengers often cover the whole cost. Choose the option that matches what your group agreed. For ride-based earnings, rather than sharing, see the rideshare earnings calculator.
For partial rides, split each leg by the people in the car during that leg. Settle up before you leave, agree on the numbers in advance, and keep the tolls and parking in the total so nobody is left to pay them alone.
Sources
Fuel cost = distance ÷ fuel economy × price is the standard calculation used by the US EPA and Department of Energy (fueleconomy.gov). The IRS standard business mileage rate (76 cents per mile for 1 July–31 December 2026) is from IRS.gov, collected 2026-10-09 in this site's data folder. Table values were computed from the formulas shown.
Frequently asked questions
How do I split gas money fairly?
Work out the total fuel cost for the trip (distance ÷ mpg × price), add tolls, and divide by the number of people. Many groups also include a per-mile allowance for wear and tear.
Should the driver pay?
It is common for the driver to pay an equal share, since the car is going anyway. If the driver is doing the others a favour, choose the option where passengers cover the whole cost and split it among themselves.
What is wear and tear?
It is the cost of tires, servicing and depreciation that a trip adds to the car. The IRS standard business mileage rate (76 cents a mile from July 2026) covers all costs of operating a car and is much higher than fuel alone; many carpools use a smaller figure, such as 10 cents a mile.
What about a passenger who joins for part of the trip?
Run the calculator separately for each leg with the people actually in the car for it, then add each person’s legs together.
Does it work in kilometres?
Yes. Switch the distance unit to km; the fuel economy input is in miles per gallon, so convert from L/100 km with the fuel economy converter first.