Road Trip Fuel Cost Calculator
Plan the fuel cost of any drive — total gallons or litres, total cost, cost split per passenger, and CO₂ emissions. Supports US (mpg), UK (mpg + £), and metric (L/100km + €) all in one place.
Trip & vehicle setup
Distance
≈ 8.4 L/100km
Use the local pump price. Highway and city averages vary by 10–20% across the same country.
- One-way distance
- 350 mi
- Total distance
- 700 mi
- $ per mi
- $0.13
Trip breakdown
Split the cost
Share this number when settling fuel money at the end of the trip.
Save fuel on the road
- Steady cruise: Driving 70 mph (110 km/h) instead of 80 mph (130 km/h) can save 10–15% fuel.
- Tyre pressure: Underinflated tyres burn up to 3% more fuel.
- Roof boxes: A loaded roof box can add 15–25% to consumption — pack inside the cabin where possible.
- Aircon vs windows: At highway speed, aircon usually wins; in city traffic, open windows save more.
Good to know
This calculator estimates pump fuel and CO₂ only. It doesn't include tolls, parking, food, accommodation, or the electricity needed for hybrid / EV charging stops. For pure EV trips, fuel economy in mpg / L doesn't apply.
About the Road Trip Fuel Cost Calculator
The Road Trip Fuel Cost Calculator works out how much petrol or gas a planned drive will cost — and how much each passenger owes when you split the bill. It supports US (miles + mpg + dollars), UK (miles + UK mpg + pounds per imperial gallon), and metric (kilometres + L/100km + euros per litre) without forcing you to convert anything by hand.
Six vehicle presets cover the most common cases (compact, sedan, SUV, truck, hybrid, minivan), and you can always type a custom number if your car sits between them. Tick the round-trip box to double the distance, set how many people are in the car, and the calculator returns total fuel, total cost, cost per person, and an estimate of CO₂ emissions for the journey.
How to Use the Road Trip Fuel Cost Calculator
- Pick your unit system. US (mi · mpg · $), UK (mi · mpg · £/imp gal), or Metric (km · L/100km · €).
- Enter the distance. Use a maps app for the route and type the one-way figure.
- Tick round trip if you're driving back. The calculator doubles the distance automatically.
- Pick a vehicle preset. Or type your car's real-world fuel economy from the dashboard average.
- Set the fuel price. Use the local pump price — the calculator shows a price-per-litre helper for UK gallons.
- Enter the number of passengers. Each row in the split-cost panel shows what one person owes.
- Read the results. Total fuel, total cost, per-person split, and CO₂ all update instantly.
Common Use Cases
Weekend getaway
350 mi round trip, 30 mpg sedan, $3.60/gal — about $42 in fuel, $21 each for two people.
Cross-country road trip
2,800 mi round trip, 24 mpg SUV, $3.80/gal — about $443. Split four ways = roughly $111 each.
UK Lake District weekend
500 mi round trip, 45 mpg diesel, £7.50/imp gallon — around £83 total.
European driving holiday
1,800 km round trip, 6.8 L/100km hybrid, €1.85/L — about €227 across the trip.
Daily commute estimate
Enter a daily one-way distance, untick round trip, then multiply per-person cost by working days to compare against carpooling or transit.
Carpool reimbursement
Use the split-cost cards to give each passenger an exact figure to send back — easier than chasing receipts later.
Frequently Asked Questions
How does the calculator handle US vs UK gallons?
They're different units. A US gallon is 3.785 litres; a UK imperial gallon is 4.546 litres — about 20% bigger. The UK preset assumes mpg refers to UK gallons and price is per imperial gallon. Switching units re-uses the same vehicle preset value where it makes sense.
What's the difference between mpg and L/100km?
They measure the same thing inversely: mpg is "how far can I go on one gallon" — higher is better. L/100km is "how much fuel do I burn over 100 km" — lower is better. Conversion: L/100km = 235.2 ÷ mpg(US). The page shows the equivalent figure as you type.
How is CO₂ estimated?
Burning 1 US gallon of gasoline releases about 8.89 kg of CO₂, and 1 litre about 2.31 kg. Diesel is slightly higher (≈ 2.68 kg/L). The figure is a tailpipe estimate only — it doesn't include refining, transport, or the carbon embedded in the vehicle itself.
Why does my car's real consumption differ from the preset?
Presets are rough US EPA combined averages. Real-world consumption depends on traffic, terrain, weather, payload, and driving style. Use the dashboard's lifetime average for the most accurate cost.
Can I use this for an EV road trip?
Not directly — EVs are priced in $/kWh, not $/gallon. This tool is for combustion or hybrid vehicles using gasoline, petrol, or diesel.
Where do I find a route distance?
Open a maps app (Google Maps, Apple Maps, Waze), search the route, and copy the distance shown. For round trips, doubling automatically beats typing twice.
Does the cost include tolls and parking?
No — this is fuel only. For a full trip budget, add tolls, parking, accommodation, and meals separately, or pair this with the Travel Budget Planner.