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Fuel Cost Calculator

Calculate gas cost for any trip or annual driving

Results are estimates for informational purposes only — not professional financial, medical, or legal advice. See how we build and verify our calculators.

Frequently Asked Questions

How do I calculate fuel cost for a road trip?

Fuel cost = (miles / MPG) × gas price per gallon. A 500-mile trip in a 30 MPG car at $3.50/gallon: (500/30) × 3.50 = 16.67 gallons × $3.50 = $58.33. Always add 10-15% for detours, idling, and AC use which can reduce real-world MPG by 5-25%.

What is the average MPG for cars in the USA?

The average new car in 2024 gets about 26-28 MPG combined. Compact sedans: 35-45 MPG. SUVs/trucks: 18-25 MPG. Hybrid cars: 40-60 MPG. Plug-in hybrids: 50-100 MPGe. Electric vehicles: 100-140 MPGe. Older vehicles from 2000-2010 average 20-25 MPG.

How much does driving cost per mile?

Total cost per mile includes: fuel (~$0.10-0.20/mile at avg MPG and gas prices), plus depreciation, insurance, maintenance, tires, and registration (typically $0.20-0.40/mile additional). The IRS standard mileage rate for 2024 is $0.67/mile for business use, reflecting total average driving costs.

How much can I save with a more fuel-efficient car?

Savings per year = annual miles × gas price × (1/old MPG - 1/new MPG). Trading from 20 MPG to 35 MPG, driving 15,000 miles/year at $3.50/gas: 15,000 × 3.50 × (1/20 - 1/35) = 15,000 × 3.50 × 0.0214 = $1,125/year savings.

Does driving speed affect fuel economy?

Yes significantly. Most cars peak efficiency at 45-55 mph. Above 55 mph, aerodynamic drag increases rapidly: fuel economy drops about 7-14% for every 5 mph over 50 mph. At 70 mph, most cars use 15-25% more fuel than at 55 mph. Highway speed limits of 65-70 mph significantly impact real-world fuel costs.

Annual Fuel Cost by MPG

MPG15,000 mi/yr @ $3.50
15 MPG$3,500
20 MPG$2,625
25 MPG$2,100
30 MPG$1,750
35 MPG$1,500
45 MPG$1,167
55 MPG$954

Factors Affecting Real MPG

Highway vs city driving (highway is more efficient)
AC use: reduces MPG by 5-25% in hot climates
Speed: drops significantly above 55 mph
Cold weather: reduces MPG by 15-24% in winter
Tire pressure: under-inflated reduces MPG by 0.5%/psi
Cargo weight: 100 lbs extra = 1% MPG reduction