Gas Mileage Calculator

Calculate your vehicle's gas mileage (MPG), estimate road trip fuel costs, and determine full-tank driving range. Compare vehicle efficiency.

Mileage & Fuel Inputs

miles
gal
$
Calculated Fuel Economy
30.0 MPG(12.8 km/L)

Driving Cost: $0.117 / mile (11.7¢/mi)

Good Fuel Economy

Cost Per Mile

$0.117

11.7¢ per mile

Total Fill-Up Cost

$35.00

15 gal tank

Metric Economy

7.8 L/100km

12.8 km / Liter

Annual 12k Miles

$1400

yearly fuel bill

Commute & Distance Expense Projection (@ 30.0 MPG & $3.50/gal)

Commute ScopeDistanceGallons UsedFuel Cost
Daily Commute (20 mi)20 miles0.67 gal$2.33
Weekly Driving (150 mi)150 miles5.00 gal$17.50
Monthly Fuel (1,000 mi)1,000 miles33.3 gal$116.67
Annual Driving (12,000 mi)12,000 miles400 gal$1400.00
Fuel Economy Optimization Tip

Driving at 65 mph instead of 75 mph on highway trips can improve your fuel economy by up to 15%. On a 500-mile road trip, this saves approximately $8.75 in gasoline while reducing engine strain.

Gas Mileage & Fuel Cost Formulas
Miles Per Gallon (MPG)
MPG =
Miles DrivenGallons Used
Trip Fuel Cost
Cost =
DistanceMPG
× Price/Gal
Cost Per Mile
$/Mile =
Price Per GallonVehicle MPG
Step-by-Step Calculation Breakdown
Example: 300 Miles on 10 Gallons of Gas at $3.50 / Gallon
1. Calculate MPG: 300 miles ÷ 10.0 gallons = 30.0 MPG
2. Calculate Cost Per Mile: $3.50 ÷ 30.0 MPG = $0.1167 / mile
3. Calculate Total Fuel Expense: 10.0 gal × $3.50 = $35.00
4. Metric Equivalent: 30.0 MPG × 0.4251 = 12.75 km/L (7.84 L/100km)
Fuel Economy & Cost:30.0 MPG (11.7¢ / Mile)

How to Maximize Fuel Efficiency

  • Maintain Proper Tire Inflation: Under-inflated tires increase rolling resistance, reducing fuel economy by up to 3%.
  • Avoid Rapid Acceleration & Hard Braking: Aggressive highway driving lowers gas mileage by 15% to 30%.
  • Minimize Extended Idling: Idling consumes up to a half-gallon of fuel per hour with zero miles traveled.

Frequently Asked Questions

How do I calculate my car's gas mileage (MPG)?
To calculate your car's MPG: Fill your tank completely and note the odometer reading (or reset your trip meter). Drive normally until you need to refuel. Fill the tank completely again and note the gallons pumped and the new odometer reading. Divide miles driven by gallons used. For example: 300 miles ÷ 10 gallons = 30 MPG. Our calculator does this automatically.
What is a good MPG for a car?
A good MPG depends on the vehicle type. Modern compact cars achieve 30-40 MPG on the highway, midsize sedans get 25-35 MPG, and SUVs and trucks typically get 15-25 MPG. The EPA reports that the average fuel economy of new 2024 vehicles is approximately 26 MPG combined. Hybrids can achieve 45-60 MPG, and plug-in hybrids can exceed 100 MPGe in electric mode.
How much does it cost to drive per mile?
The cost per mile depends on your vehicle's fuel efficiency and local gas prices. At $3.50 per gallon, a car getting 30 MPG costs about 11.7 cents per mile. An SUV getting 18 MPG costs about 19.4 cents per mile. The IRS mileage reimbursement rate for 2025 is 70 cents per mile (including depreciation, maintenance, and insurance, not just fuel).
Can I improve my gas mileage?
Yes. Proper tire inflation (checked monthly) improves MPG by up to 3%. Removing excess weight (100 lbs reduces MPG by ~1%). Smooth acceleration and braking can improve city MPG by 10-40%. Using cruise control on highways maintains steady speed. Avoiding excessive idling saves fuel. Keeping up with regular maintenance (air filters, spark plugs, oil changes) ensures optimal efficiency.

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