Gas Money Calculator
A 420-mile trip at 28 MPG and $3.45 a gallon burns $51.75 of gas, and $10.25 of tolls brings it to $62.00: $15.50 each for four people. The gas money calculator splits your own trip with or without the driver, and for riders picked up partway.
Gas money per person
- Each person pays $62.00 split 4 ways, driver included.
- $15.50
- Total to split $51.75 of fuel plus $10.25 of tolls and parking.
- $62.00
- Fuel used 420 miles at 28 MPG and $3.45 a gallon.
- 15 US gallons
- Cost per mile for the car $0.04 a mile for each of the 4 people.
- $0.15
- The driver's share 25% of the cost.
- $15.50
- If the driver rode free
- $20.67 each
| Person | In the car | Share | Pays |
|---|---|---|---|
| Driver | 420 miles | 25% | $15.50 |
| Rider 1 | 420 miles | 25% | $15.50 |
| Rider 2 | 420 miles | 25% | $15.50 |
| Rider 3 | 420 miles | 25% | $15.50 |
| Total | 100% | $62.00 |
How the Fuel Cost Calculator works
To calculate gas money, work out the fuel the trip burns, price it, add the costs everyone shares, and divide.
With the driver or without. There are two common ways to share a car, and neither is a rule, so agree on one before you leave. In the first the driver is one of the people splitting the cost, and each of the four pays $15.50. In the second the driver supplies the car and the driving and the riders pay for the fuel between them: three riders split $62.00, which is $20.67 each. That does not divide to the cent, so one rider pays $20.66 to make the total exact.
Riders picked up partway. A car burns about the same fuel with one person in it as with four, so the fair split is by stretch of road: each stretch costs what it costs, and whoever is aboard for it shares it. Say one rider joins for the last 120 of the 420 miles. Those 120 miles are 120/420 of the $62.00, or $17.71, shared four ways: $4.43 each. The first 300 miles cost $44.29, shared by the three who were aboard: $14.76 each. The rider who joined late pays $4.43, and everyone else pays $14.76 + $4.43 = $19.19. With the driver riding free, the late rider pays $5.90 and the two other riders $28.05 each.
Another way people split it is by passenger miles: everyone pays the same rate per mile ridden. Here that is 1,380 passenger miles, and the late rider's 120 come to $5.39. That is more than the $4.43 by stretch, because a flat rate per passenger mile has the late rider covering part of the stretch when the car carried fewer people. The calculator uses the stretch method.
Round trips and units. For a round trip the distance is both ways. A rider who is dropped off where they were picked up has a ride that sits inside everyone else's, which is all the stretch method needs. The economy can be in MPG or liters per 100 km; the price is per gallon or per liter to match.
What gas money leaves out. Fuel and tolls are the costs that come with this one trip. The car also wears: the IRS business standard mileage rate, 76 cents a mile from July to December 2026, is meant to cover the full cost of running a car, and 420 miles at that rate is $319.20. Some drivers ask for more than the gas for that reason. The split here covers fuel, tolls and parking only.
Fuel Cost Calculator FAQ
How do you calculate gas money?
Divide the distance by the car's MPG to get the gallons, multiply by the price, add tolls and parking, and divide by the number of people paying. 420 miles at 28 MPG and $3.45 a gallon is $51.75; with $10.25 of tolls it is $62.00, or $15.50 each for four people.
Should the driver pay for gas too?
That is for the group to agree. If the driver pays a share, four people split $62.00 at $15.50 each. If the riders cover it as thanks for the car and the driving, three riders pay $20.67 each.
How do you split gas when someone is picked up partway?
Split each stretch of road among whoever was in the car for it. On a 420-mile, $62.00 trip, a rider who joins for the last 120 miles pays a quarter of those miles' cost, $4.43, and the other three pay $19.19 each.
How much gas money should I give for a short ride?
Your share of the fuel for the distance you rode. A 30-mile ride at 28 MPG and $3.45 a gallon burns about 1.07 gallons, $3.70 of gas. Split with the driver, that is $1.85 each.