Gas Trip Cost Calculator
Planning a road trip? Enter your trip distance, your vehicle's fuel efficiency, and the current gas price to instantly see how much you'll spend on fuel. You can also split the cost among multiple passengers. The calculator supports both US units (miles/MPG/gallons) and metric units (km/L per 100km/liters) so it works wherever you're driving.
When to use this calculator
- Estimating fuel budget before a long road trip
- Comparing the fuel cost of two different vehicles for the same route
- Splitting gas costs fairly among carpoolers or travel companions
- Checking whether renting a more fuel-efficient car saves money on a trip
- Calculating fuel costs for a cross-country drive in the US
- Planning a road trip budget in countries using metric units
How it works
2 min readWhat is gas trip cost?
Gas trip cost is the total fuel expense for a road journey calculated by multiplying distance traveled by fuel consumption rate and current gas prices. A 500-mile trip in a 28 MPG vehicle at $3.45 per gallon costs approximately $61.61. Dividing this among passengers provides per-person fuel expenses for fair cost sharing.
How It Works
The calculator uses a straightforward formula to determine how much fuel your trip will consume and what it will cost.
Formula (Imperial)
Gallons needed = Trip distance (miles) ÷ MPG
Total fuel cost = Gallons needed × Gas price per gallon
Cost per person = Total fuel cost ÷ Number of passengersFormula (Metric)
Liters needed = Trip distance (km) × (L/100km ÷ 100)
Total fuel cost = Liters needed × Gas price per liter
Cost per person = Total fuel cost ÷ Number of passengersWorked Example (Imperial)
You're driving 500 miles in a car that gets 28 MPG, and gas costs $3.45 per gallon, with 4 passengers:
| Step | Calculation | Result |
|---|---|---|
| Gallons needed | 500 ÷ 28 | 17.86 gal |
| Total cost | 17.86 × $3.45 | $61.61 |
| Per person | $61.61 ÷ 4 | $15.40 |
Worked Example (Metric)
You're driving 800 km in a car rated at 9 L/100km, and gas costs $1.55 per liter, with 2 passengers:
| Step | Calculation | Result |
|---|---|---|
| Liters needed | 800 × (9 ÷ 100) | 72 L |
| Total cost | 72 × $1.55 | $111.60 |
| Per person | $111.60 ÷ 2 | $55.80 |
US Reference Values (2026)
Limitations
Frequently asked questions
What is the average gas price in the US in 2026?
As of early 2026, the US national average for regular unleaded gasoline is approximately $3.45 per gallon, according to the US Energy Information Administration (EIA). Prices vary significantly by state — California often exceeds $4.50/gal while Gulf Coast states tend to be lower.
What MPG should I enter if I don't know my car's fuel economy?
Check the EPA fuel economy label on your vehicle or search the EPA's fueleconomy.gov database. The average 2025 model year car gets about 28 MPG combined. Compact cars: ~34 MPG. SUVs/trucks: ~20–22 MPG. Hybrids: ~45–55 MPG. Use the combined city/highway figure for most trips.
How do I convert L/100km to MPG?
Use the formula: MPG = 235.21 ÷ (L/100km). For example, 9 L/100km = 235.21 ÷ 9 ≈ 26.1 MPG. Conversely, MPG to L/100km: L/100km = 235.21 ÷ MPG.
Does this calculator account for city vs. highway driving?
No — it uses a single efficiency figure you enter. For the most accurate result, estimate what mix of city and highway driving your trip involves. If it's mostly highway, use your vehicle's highway MPG rating. If mixed, use the combined rating from fueleconomy.gov.
How does the cost split work?
The total fuel cost is divided equally among the number of passengers you enter. Enter 1 (the default) if you're not splitting. Enter 2 for two people splitting, and so on. The calculator assumes each person pays an equal share.
Why does my actual fuel cost differ from the estimate?
Real-world MPG varies based on speed (fuel economy drops sharply above 65 mph), air conditioning use, cargo weight, hills and elevation, tire pressure, and driving style. Aggressive acceleration and braking can reduce efficiency by 15–30% versus steady highway cruising.
Can I use this for a round trip?
Yes — simply double your one-way distance and enter the total. For example, a 300-mile one-way trip becomes 600 miles for the full round trip. This assumes similar conditions on both legs.
What gas price should I use for metric calculations?
Enter the price per liter in your local currency. In Canada, expect roughly CAD $1.60–$1.90/L in 2026 depending on province. In the UK, roughly GBP £1.55–£1.70/L. In Germany, roughly EUR €1.75–€1.95/L. Check a current local source for the most accurate price.
Does the calculator include the cost of oil, tolls, or wear and tear?
No — it calculates fuel cost only. The IRS standard mileage rate (67 cents/mile for 2024, updated yearly) is a broader measure that includes depreciation, maintenance, and fuel. For a full trip cost estimate, add tolls and consider the IRS rate instead.