How to Estimate Trip Fuel Cost - Step by Step
The fuel cost calculator needs three numbers - distance, fuel efficiency and fuel price - and shows the fuel a trip needs and what it costs, live as you type. Nothing is installed and nothing you enter leaves the browser. Here is each step with a worked example.
Step 1 - open the tool and pick your units
Go to the fuel cost calculator. The units dropdown offers US (miles, MPG, price per gallon) and metric (km, L/100km, price per liter). If you switch later, the values you already typed are converted in place - the result stays equivalent.
Step 2 - enter the distance
Type the one-way distance from your route planner. For there-and-back, tick the round-trip checkbox instead of doubling by hand - the tool doubles the distance for you and says so in the result line.
Step 3 - enter your vehicle's efficiency
Use the figure from your car's trip display or the owner's manual: MPG in US units, or liters per 100 km in metric. A mid-size gasoline car is typically around 30 MPG (about 7.8 L/100km); if in doubt, enter a slightly worse figure so the estimate errs on the safe side.
Step 4 - enter the fuel price and travelers
Type the pump price you actually pay, in your own currency - the tool never fetches prices, so the output is a plain number without a currency symbol. If several people split the cost, set the travelers field and a per-person line appears.
Step 5 - read the result
Three outputs update on every keystroke: fuel needed (gallons or liters), total fuel cost, and cost per mile or km. The worked examples:
| Input | US example | Metric example |
|---|---|---|
| Distance | 300 miles | 480 km |
| Efficiency | 30 MPG | 7.8 L/100km |
| Fuel price | 3.50 per gallon | 1.65 per liter |
| Fuel needed | 10.0 gallons | 37.4 liters |
| Total cost | 35.00 | 61.78 |
When the estimate is done, the use-cases guide shows where this math pays off, and the comparison weighs it against trip computers and price apps.
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