How to calculate gas money for a trip
To estimate gas money, divide the total trip distance in miles by your car’s miles per US gallon, then multiply by the price per US gallon. Add any tolls and parking. Divide the resulting total between the people who agreed to pay.
GasSplit estimates fuel consumed on your trip. It assumes the driver paid all included costs; it does not track multiple payers or reimburse an entire tank automatically.
Calculate your gas split →1. Count the distance you will actually drive
Enter the whole route with Include return trip unchecked if your distance already includes the return drive. For the same route out and back, enter the one-way distance and check Include return trip: 150 miles becomes 300 miles. If the return route is different, add both distances yourself and leave the checkbox unchecked.
After a trip, Odometer subtracts the start reading from the end reading. That difference already includes all recorded driving, so the round-trip multiplier does not apply in odometer mode. The calculator shows the total distance used.
2. Estimate fuel use and cost
Have your distance, average fuel economy and price per gallon or liter ready. Use your measured average fuel economy when available. Find my car can supply an EPA combined estimate for a supported US-market vehicle, which you can edit.
Which fuel economy should I enter?
Use your car’s measured average for similar driving when available. To measure it yourself, record the distance driven between two full tanks and the fuel added to refill to the same level. For MPG, divide miles driven by US or Imperial gallons added, matching your chosen unit. For L/100km, divide liters added by kilometers driven, then multiply by 100. One arbitrary fuel receipt does not tell you how much fuel a trip consumed.
| Fuel economy | Estimated fuel cost |
|---|---|
| MPG (US) | Miles ÷ MPG × price per US gallon |
| MPG (UK) | Miles ÷ MPG (UK) × 4.54609 × price per liter |
| L/100km | Kilometers × L/100km ÷ 100 × price per liter |
| km/L | Kilometers ÷ km/L × price per liter |
The calculator supports mixed distance and fuel units by converting them internally. One mile equals 1.609344 kilometers; one US gallon equals 3.785411784 liters. One Imperial gallon equals 4.54609 liters. Choose MPG (US) or MPG (UK) to match your vehicle; they are not interchangeable. The US, UK and Metric presets set units and currency together, and individual fields remain adjustable. Changing currency does not convert money: enter prices in the selected currency.
3. Work out the total and each person’s share
A US road trip: 300 miles, four people
- 150 miles each way means 300 miles in total.
- At 30 MPG, estimated fuel use is 300 ÷ 30 = 10 US gallons.
- At USD 3.50 per gallon, fuel costs USD 35.00.
- With four people including the driver sharing equally, each share is USD 8.75.
- The three passengers pay the driver USD 26.25 altogether; the driver’s own share is USD 8.75.
If you also enter USD 9.00 in tolls and USD 4.00 in parking, the trip total becomes USD 48.00. Each of four people pays USD 12.00 and the driver collects USD 36.00. Enter extras for the whole trip once; Include return trip doubles distance, not tolls or parking.
A metric example: 200 km, four people
At 8 L/100km, a 200 km trip uses an estimated 16 liters. At EUR 1.75 per liter, fuel costs EUR 28.00. Each of four people pays EUR 7.00 and the driver collects EUR 21.00. Entering 12.5 km/L gives the same result.
Who counts as a person, and does the driver pay?
People in the car always includes the driver. Everyone pays divides the included costs among everyone. Passengers only excludes the driver from fuel and all included extras. Agree on the rule first; see how to split gas money with friends fairly.
Why can two people owe slightly different amounts?
Some totals do not divide evenly into the currency’s smallest unit. USD 10.00 split three ways is USD 3.34, USD 3.33 and USD 3.33. GasSplit allocates the extra cent to a passenger first and keeps the driver last. The shares add up to the total. Fuel is rounded half up before entered tolls and parking are added; JPY uses no decimal places and KWD uses three.
Common input mistakes to avoid
- Doubling an already complete route: leave Include return trip unchecked for a distance that includes the drive home.
- Confusing fuel economy units: 30 MPG is not 30 L/100km. Check the unit beside your input. Zero fuel economy is invalid.
- Using a tank receipt as trip consumption: a fill-up may cover fuel left for future journeys. Estimate the fuel consumed on this trip, or agree separately on actual trip-only expenses.
- Counting only passengers: enter everyone in the car, then choose who pays.
- Checking number separators: 3.60 and 3,60 both mean three point six. Ambiguous entries such as 1,234 require clarification: use 1234 for a whole number or 1.234 for a decimal. Explicit mixed formats such as 1,234.50 or 1.234,50 are accepted.
How accurate is the estimate?
Arithmetic can be exact while fuel use remains an estimate. Traffic, speed, weather, terrain, load and driving style can change consumption. The EPA explains why your mileage can differ from its estimates. Maintenance, insurance, depreciation and electricity are outside this calculator.
Where do vehicle data and reference prices come from?
Vehicle records and optional US reference fuel prices come from FuelEconomy.gov’s public services. The vehicle directory covers supported US-market gasoline and diesel models, including conventional hybrids; electric, plug-in and multi-fuel models are not automatically prefilled. An unavailable vehicle can still be calculated using a suitable manual fuel-economy value.
Reference prices are available for USD estimates. They are not local station quotes. The feed usually updates weekly, but does not supply a price publication date, so the bill identifies the retrieval time separately. Use the price you paid when possible.
Copy a clear bill to your group
Copy bill provides text, and Save image creates a local PNG preview for download. Neither creates a public bill page. The separate Share GasSplit action recommends the tool without sharing your trip. Trips stay in page memory; see privacy notes for saved preferences, lookups and analytics.
Calculate your gas split →