Trip gas calculator
Add up to six legs, enter your mpg and the gas price, and see the cost of each leg, the total and how many tanks the trip needs.
The estimate updates as you type. Nothing you enter leaves this page.
Estimated gas cost for the trip
$/ trip
- Gallons used
- gal
- Cost per person
- $
- Tanks of fuel
- tanks
Estimate from the numbers you entered.
How this is calculated
The legs are added together, doubled if you tick return trip, and divided by your mpg to give gallons. Gallons times the price per gallon is the total. Each leg’s cost uses the same mpg and price, so the legs show where the money goes. Cost per person is the total divided by the travellers, and tanks is gallons divided by the tank size.
gallons = (leg 1 + leg 2 + … ) × (2 if return) ÷ mpg
The method, the constants and the limits are written out in how fuel cost is calculated.
Measuring each leg
Type the miles for each leg of the drive. Any map app will give you a figure: set the start and end of one leg, read the distance, then do the next leg. Splitting the trip this way makes the cost of a detour or an extra stop visible, because that leg gets its own line in the table. This calculator does not look up routes. It uses the distances you type.
If you drive the same route back, tick the return trip box instead of entering the legs twice.
Worked example: three legs, there and back
Example numbers: legs of 120, 80 and 50 miles, 28 mpg, gas at $3.50 a gallon, a 14-gallon tank and two people, driving the whole route back.
- Legs: 120 + 80 + 50 = 250 miles. Return trip: 250 × 2 = 500 miles.
- Gallons: 500 ÷ 28 = 17.86.
- Cost: 17.86 × $3.50 = $62.50. Per person: $31.25.
- Tanks: 17.86 ÷ 14 = 1.3, so about 2 tanks if you count a part-tank as one.
| Leg | Miles driven | Fuel cost |
|---|---|---|
| Leg 1 | 240 | $30.00 |
| Leg 2 | 160 | $20.00 |
| Leg 3 | 100 | $12.50 |
What is not included
Tolls, parking, food and lodging are not fuel, so they are not in the result. Neither are detours you have not entered, idling in traffic, or the extra fuel a loaded car or a roof box uses. Leg costs are rounded to the cent one at a time, so they can differ from the total by a cent. For a quick check of how much fuel a trip takes, read how much gas you will use on your trip.
To split the bill, use the gas money calculator, which can add tolls. If you want to turn miles and a fill-up into an mpg figure first, start with the fuel consumption calculator. The single-leg version is on the fuel cost calculator home page.
Common questions
How many legs can I enter?
Up to six. Leg 1 is required and the others are optional, so leave a box blank if you do not need it.
How is the number of tanks worked out?
It is the gallons used divided by the tank size you enter. The sentence under the result rounds up to whole tanks, counting a part-tank as one. Nothing is shown if you leave the tank size blank.
Does it include a return journey?
Only if you tick the return trip box. It then drives every leg a second time.
Can I change the gas price?
Yes. The price field starts with an example value, not a live price. Replace it with the price you expect to pay.