Fuel Cost Calculator
Calculate the fuel cost of a trip from the distance, your fuel economy and the price of fuel.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
Estimate fuel for the entered distance using US miles, US miles per gallon (mpg), and fuel price in US dollars per US gallon. The route and fuel economy are your inputs; traffic, terrain, weather and driving style are not modeled.
Worked example
calculated with the default values below
Distance (one way) 300 mi · Fuel economy (US mpg) 30 mpg · Fuel price (USD per US gal) 3.5 USD/US gal · Round trip One way Fuel cost 35.00 USD · Total distance 300 mi · Fuel needed 10.00 gal · Fuel needed 37.85 L · Cost per mile 0.117 USD/mi
General background references
Disclaimer
These calculators give estimates for general information only. Real fuel consumption, performance and range vary with driving style, load, terrain, temperature and vehicle condition. Do not rely on these results for towing limits, payload or braking decisions — use the rating plate of your vehicle.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
D = d x k; gal = D / mpg; L = gal x 3.785411784; C = gal x p; perMile = C / D
- d
- one-way distance (miles)
- k
- trip factor: 1 or 2
- D
- total distance
- mpg
- fuel economy (US mpg)
- p
- fuel price per gallon
- C
- total fuel cost
k = 2 for a round trip. Gallons are US gallons (1 US gal = 3.785411784 L); fuel use and cost are 0 when mpg = 0.
Frequently asked questions
Which units does this fuel estimate use?
Distance is in US miles, fuel economy is US miles per US gallon (mpg), fuel price is USD per US gallon, and the cost-per-mile result is USD per mile. The liters output converts the US-gallon estimate; it does not change the price calculation.
How does the round-trip option affect cost?
It doubles the entered one-way distance before calculating gallons and cost. For example, 300 miles at 30 mpg and $3.50 per US gallon uses 10 gallons and costs $35 one way, or 20 gallons and $70 round trip, before real-world variation.