How this gas cost calculator for road trips works
Fuel = (miles ÷ MPG) × price; gallons and liters scale with your units (this tool uses US gallons and MPG — metric drivers: L/100km × 2.3521 = MPG, liters = gallons × 3.7854). Tolls and cost-splitting are added at the end. Price check: AAA's Daily Fuel Gauge publishes state averages every morning if you want today's number instead of an assumption.
Frequently asked questions
What is a good MPG for cost estimates?
EPA combined averages for 2026: compact sedan ~32 MPG, midsize SUV ~24 MPG, full-size truck 17–20 MPG, EV (enter as equivalent). Real highway driving drops 10–15% versus the window sticker due to AC, speed and cargo — round down.
How do I get accurate toll costs?
Use your state's turnpike toll calculator or the E-ZWay app; tolls have climbed with every interstate funding bill and can now rival fuel on long Eastern routes — this tool adds them to the fuel line for the true total.
Is this accurate for electric cars?
Not directly — EV cost per mile uses kWh rates (home ~$0.16, public fast-charge ~$0.48). Equivalent trick: divide your car's MPGe by 4 to approximate an 'effective MPG', then use 3.5× the gasoline price figure; or better: (miles ÷ efficiency) × $/kWh works directly.