Gas Cost for Trip Calculator
Estimate fuel cost for any trip. Pure arithmetic.
What this tool does
Multiplies your trip distance by your vehicle's fuel consumption rate by the current fuel price. The result is an estimate of how much gas the trip will cost. Supports both US units (miles, MPG, USD per gallon) and metric (kilometers, L per 100 km, currency per litre). Calculation is purely arithmetic and runs in your browser. The tool does not suggest routes, recommend gas stations, or estimate real-world conditions like traffic, weather, or driving style.
How to use it
Pick units. Enter the one-way distance. Toggle Round trip if you want the cost both ways. Enter your vehicle's fuel consumption (the number on the window sticker, or your dashboard's average if you have one). Enter the current fuel price. Press Calculate. Example: a 100-mile one-way trip in a 28 MPG car at $3.50 a gallon costs about $12.50 each way.
Common use cases
- Comparing the gas cost of two routes you are choosing between based on distance.
- Estimating the fuel portion of a road-trip budget.
- Splitting fuel costs evenly among carpool passengers.
- Deciding whether driving versus flying is cheaper for a specific trip.
- Quick mental arithmetic check before a long drive.
Common pitfalls
- Real-world MPG is variable. Window-sticker numbers assume EPA test conditions. Highway driving usually meets or beats them; stop-and-go city driving and steep terrain typically fall short. Use your dashboard's actual average for a more realistic estimate.
- Fuel grade matters. If your vehicle requires premium and you used a regular price, the cost is higher than the estimate. Check your owner's manual.
- This is fuel only. Total trip cost includes wear on the vehicle, tolls, parking, and food. Federal mileage reimbursement rates exist precisely because real cost-per-mile is well above the fuel cost alone.
Frequently asked questions
- Why does my actual mileage differ from the EPA window-sticker number?
- EPA test conditions (controlled lab dynamometer with specific drive cycles) do not match real-world driving. Highway driving with steady speeds, no AC, and gentle acceleration usually meets or beats the sticker. Stop-and-go city traffic, mountainous terrain, cold weather, AC use, roof racks, and aggressive driving all reduce real-world MPG. Use your dashboard lifetime average (most modern cars track this) for a realistic input.
- Should I use my dashboard MPG or the gas-pump reset number?
- Both have biases. Dashboard MPG can drift over time and has been documented to read 1-3 MPG too high on some makes. The reset-the-trip-and-divide-tank-by-miles method is more accurate but requires consistent fill-up technique (always fill to the same auto-shutoff point). For a single estimate, either is fine; for cross-comparing vehicles, prefer the manual method over multiple tanks.
- How do I convert MPG to L/100km or vice versa?
- They are reciprocals with a unit conversion. MPG to L/100km: divide 235.21 by your MPG. So 28 MPG is about 8.4 L/100km. L/100km to MPG: divide 235.21 by your L/100km. So 7 L/100km is about 33.6 MPG. The unit toggle in the tool handles the conversion automatically; the formula is a useful mental check.
- Does this account for tolls, parking, and wear?
- No. This is fuel cost only. Total trip cost includes wear-and-tear on the vehicle (tires, oil, brakes, depreciation), tolls, parking, food, lodging. The IRS standard mileage rate (around $0.67 a mile in 2024) attempts to capture all of these and is much higher than fuel alone (typically $0.10-0.15 a mile). Use the IRS rate for reimbursement; use this tool for budgeting just the gas line item.
- What about EVs and hybrids?
- EVs use kWh per 100 miles instead of MPG. Multiply by your electricity cost per kWh; the arithmetic is identical, just substitute units. Hybrids work fine because their MPG is a single combined figure that already includes the electric portion. PHEVs (plug-in hybrids) are tricky: short trips run mostly on electricity, long trips mostly on gas; the EPA combined number is misleading for either extreme.
- How do I estimate gas cost for a long road trip with multiple stops?
- Add up the legs (Atlanta to Asheville, Asheville to Knoxville, etc.) and run the total. If fuel prices vary significantly across regions, do separate calculations for each leg with the regional price. AAA Fuel Cost Calculator and GasBuddy price maps both give regional pricing input for US trips.
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