Fuel Cost CalculatorEstimate Gas Cost for Any Trip
Use this free fuel cost calculator to estimate your total gas cost for any trip. Enter your distance, fuel efficiency, and current fuel price -- supports MPG, L/100km, and km/L -- and get an instant result with a full step-by-step breakdown.
Getting started
How to use this fuel cost calculator
1
Choose your unit system
Select Imperial (MPG), Metric L/100km, or Metric km/L.
2
Enter trip distance
Enter the one-way distance. Enable 'Round trip' if you are driving both ways.
3
Enter fuel details
Enter your vehicle fuel efficiency and the current fuel price.
4
Read results
Your total trip fuel cost, fuel used, and cost per mile appear instantly.
The calculation
Step-by-step: how your fuel cost was calculated
1
Calculate fuel used
Fuel Used = Distance / MPG
= 300 / 28
2
Calculate total trip cost
Trip Cost = Fuel Used x Price per gallon
= 10.71 x $3.50
Cost per mile = $37.50 / 300 miles = $0.1250 per mile
Formulas
Fuel cost formula
Imperial (MPG)
Fuel Used (gal) = Distance (miles) / MPG
Trip Cost = Fuel Used x Price per gallon
Metric -- L/100km
Fuel Used (L) = Distance (km) x L/100km / 100
Trip Cost = Fuel Used x Price per liter
Metric -- km/L
Fuel Used (L) = Distance (km) / km/L
Trip Cost = Fuel Used x Price per liter
Interpreting
Interpreting your fuel cost result
Total trip cost in context
A short city commute of 20-30 miles at 30 MPG and $3.50/gal costs roughly $2.30-$3.50 in fuel. A regional trip of 300 miles at the same efficiency costs around $35. A 1,000-mile highway road trip at 32 MPG and $3.50/gal costs approximately $109.
Cost per mile as an efficiency metric
The cost-per-mile figure is often the most useful number for comparison. It tells you what every additional mile of driving costs in fuel, independent of trip length. At $3.50/gal and 28 MPG, every mile costs $0.125.
Round trip vs one-way
When planning a return journey on the same route, the round-trip calculation is simply twice the one-way cost. Enable the Round trip toggle to ensure your budget accounts for the full journey.
Estimate vs actual cost
Real-world fuel consumption varies by speed, load, terrain, temperature, and driving style. Your actual cost may differ from the estimate by 5-15% in normal conditions.
Reference Table
Typical fuel economy by vehicle type
Tips & Common Mistakes
Quick tips to reduce your fuel cost
Drive at 55-65 mph.
Fuel consumption rises sharply above 65 mph due to aerodynamic drag. Slowing from 75 to 65 mph can improve fuel economy 10-15%.
Keep tires inflated.
Under-inflated tires increase rolling resistance. Check pressure monthly -- every 1 PSI underinflation reduces MPG by ~0.2%.
Use cruise control.
Steady speed on highways eliminates the fuel-wasting acceleration/deceleration cycle of manual speed management.
Common fuel cost estimation mistakes
Using the highway MPG rating for city driving
EPA ratings list highway and city MPG separately. A vehicle rated 35 MPG highway might only achieve 25 MPG in city driving. Using the highway figure for a primarily urban trip will underestimate your fuel cost significantly.
Forgetting to adjust for heavy loads
Towing a trailer, hauling cargo, or driving with a full passenger load significantly reduces fuel efficiency.
Using yesterday's price for tomorrow's trip
Fuel prices fluctuate daily and vary significantly by station, neighborhood, and highway exit. For budgeting purposes, add a 10-15% buffer to account for price variation along your route.
FAQ
Frequently asked questions
Q
How is fuel cost calculated?
The formula depends on your unit system. For Imperial (MPG): Fuel Used = Distance / MPG, then Trip Cost = Fuel Used x Price per gallon. For Metric L/100km: Fuel Used = (Distance x L/100km) / 100, then Trip Cost = Fuel Used x Price per liter. For km/L: Fuel Used = Distance / km/L, then Trip Cost = Fuel Used x Price per liter. This calculator handles all three automatically and shows the full step-by-step working with your actual values.
Q
What is the difference between MPG and L/100km?
MPG (miles per gallon) measures how many miles you travel per gallon -- a higher number means better fuel efficiency. L/100km measures how many liters you need per 100 km -- a lower number means better efficiency. They are inversely related: L/100km = 235.21 / MPG. A car at 30 MPG uses approximately 7.8 L/100km. Choose whichever unit matches your vehicle's dashboard or specifications.
Q
What is km/L and how do I use it?
Kilometers per liter (km/L) is the metric equivalent of MPG -- how far your vehicle travels on one liter of fuel. It is widely used in Asia and Latin America. Higher numbers mean better efficiency. To convert: L/100km = 100 / km/L, and MPG = 2.352 x km/L. Enter your km/L value in the Metric km/L tab of this calculator.
Q
Can I calculate round-trip fuel costs?
Yes. Toggle the Round trip option and the calculator automatically doubles your distance before computing -- so the total fuel cost, fuel used, and cost per mile all reflect both legs of the journey. Enter the one-way distance only; the calculator handles the doubling.
Q
What is the average fuel efficiency for a car?
The average new passenger car in the US achieves about 28 MPG combined (approximately 8.4 L/100km). Compact cars typically reach 30-40 MPG, midsize sedans 25-35 MPG, full-size trucks 16-22 MPG, and hybrids 40-55 MPG. Check your vehicle's EPA label or owner manual for the exact fuel economy rating -- real-world efficiency often differs from the rated figure by 10-15%.
Q
How can I reduce my fuel cost per trip?
The most effective methods are: drive at steady speeds (55-65 mph uses far less fuel than 75+ mph), keep tires properly inflated (under-inflation raises fuel cost by up to 3%), use cruise control on highways to avoid fuel-wasting speed fluctuation, reduce unnecessary cargo weight (every 100 lbs cuts efficiency by ~1%), and plan routes to avoid traffic. Regular maintenance -- air filter, spark plugs, clean oil -- also contributes to consistent fuel economy.
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