What this calculator does
After a road trip, one person enters the fuel, the tolls and the parking, and the calculator works out each person's share and the transfers that settle it. Fuel is split by who was in the car on each leg, so a friend who joined for the last day pays for the last day. Tolls and parking are split evenly between the people each one was for. Every number shows the working.
You enter the people, a currency and whether distances are in miles or kilometers; the fuel, either as receipts or as an estimate; and, if anyone joined or left partway, the legs of the trip with their distance and who rode. Tolls and parking are optional.
Fuel: receipts or an estimate
- A fuel receipt. The amount you paid at the pump, who paid it, and the leg it was for. With no leg picked, it is split between the legs by distance.
- An estimate from distance. The distance, the car's fuel efficiency and the price per gallon or liter, and who paid. With mpg: distance ÷ mpg × price per gallon. With L/100km: distance × L/100km ÷ 100 × price per liter. With km/L: distance ÷ km/L × price per liter. The result is rounded to the cent once, at the end.
Use one way per leg. A leg with a receipt and an estimate would count the same fuel twice, so the calculator asks you to keep one.
Driver relief
Each leg can have a driver. The group picks one setting for the whole trip, and it applies to fuel only:
- Even. Everyone in the car on a leg pays the same part of that leg's fuel.
- Driver pays half a share. The driver counts 1 and each rider 2, so the driver pays half of what each rider pays. This is half a share, not half the fuel.
- Driver skips fuel. The riders share the leg's fuel and the driver pays none. On a leg where the driver was alone, there is nobody else to pay, so that leg is split evenly (the driver pays it) and the result says so.
Under the transfers, the result shows each driver's share under all three settings side by side, so the group can see what the choice is worth.
An example
Reading the result
The table gives each person's fuel share, toll and parking share, what they paid and their balance: + gets money back, − sends money. Below it is the line comparing the three driver settings, then the transfers. "Share to the group chat" makes a link where each friend taps their name and sees every leg they rode, how its fuel was divided and their part of each toll.
Cases a road trip has
- The car started with a full tank. The receipts then miss the fuel that was already in it. Either fill up to full at the end and enter that receipt too, or leave the receipts out and enter an estimate from the distance driven.
- A receipt with no leg. It is split by leg distance, so every leg needs its distance. If you only know where the car was filled, pick that leg instead; the receipt then belongs to that leg alone.
- Someone drove part of the way. Each leg has its own driver, so two people who took turns each get the relief on the legs they drove.
- The car owner did not ride. Add them, then leave them out of every leg: they pay no fuel. If the group agrees to give them an amount for the car, enter it under tolls and parking as paid by the owner and shared by the riders.
Common questions
How do you calculate gas for a road trip?
Divide the distance by the car's miles per gallon, then multiply by the price per gallon. 300 miles at 25 mpg is 12 gallons; at $3.459 a gallon that is $41.508, which rounds to $41.51. With liters per 100 km, multiply the distance by the figure, divide by 100, then multiply by the price per liter: 500 km at 7 L/100km and 1.80 a liter is 35 liters, or 63.00.
How do you split gas money with friends?
Add up the fuel, then divide it between the people who were in the car. If everyone rode the whole way, that is an even split. If someone joined or left partway, split the trip into legs and divide each leg's fuel between the people on it, so nobody pays for miles they were not there for.
Should the driver pay for gas?
It is up to the group. The calculator has three settings: even, where the driver pays like everyone else; half a share, where the driver pays half of what each rider pays; and skips fuel, where the riders share the fuel and the driver pays none. Tolls and parking stay even in all three. The guide on splitting gas on a road trip goes through both sides.
What if we have the fuel receipts and also know the distance?
Use one or the other for each leg, not both, or the fuel is counted twice. Receipts are what was really paid; the estimate is for legs where nobody kept a receipt, or for a car that started with a full tank. The calculator stops and asks you to keep one when a leg has both.
How do you split a fuel receipt between legs?
A receipt with no leg picked is split between the legs by distance. A $160.00 receipt on a trip of a 300-mile leg and a 100-mile leg puts $120.00 on the first and $40.00 on the second, and each leg's part is then split between the people on it. If a leg has no distance, pick a leg for the receipt instead.
What it does not do
- It does not look up fuel prices or a car's mpg. You enter them from the receipt or the car's documents.
- It works in one currency and does not convert. For a trip paid in several currencies, use the trip settle-up.
- It splits fuel, tolls and parking. Rooms, meals and tickets go into the trip settle-up.
Every result is a reference estimate for the group to agree on; the disclaimer says what that covers. The methodology page lists the rules, including who carries a leftover cent. Whether the driver should pay less, and what a friend who rode one leg owes, is the subject of the guide on splitting gas on a road trip.