CalculateY
Quick Answer
Driving 300 miles on 10 gallons of gas gives 30 MPG. At $3.50 per gallon, that trip costs $35 total, or about $0.12 per mile.
Common Examples
| Input | Result |
|---|---|
| 300 miles, 10 gallons | 30.00 MPG, 3.33 gal/100mi |
| 250 miles, 12.5 gallons | 20.00 MPG, 5.00 gal/100mi |
| 400 miles, 8 gallons | 50.00 MPG, 2.00 gal/100mi |
| 150 miles, 6 gallons, $3.50/gal | 25.00 MPG, $0.14/mile, $21.00 total |
How It Works
The formula
MPG = Distance / Gallons Used
Where:
- Distance = total miles driven between fill-ups (or for a full tank)
- Gallons Used = fuel consumed over that distance
To calculate cost per mile when you know the gas price:
Cost per Mile = (Gallons Used x Price per Gallon) / Distance
Gallons per 100 Miles = (Gallons Used / Distance) x 100
Gallons per 100 miles is the inverse of MPG and is used by the EPA alongside MPG on new vehicle window stickers. It gives a more linear sense of fuel savings: going from 10 to 20 MPG saves 5 gallons per 100 miles, while going from 20 to 30 MPG saves only 1.67 gallons per 100 miles. This is why improving a low-MPG vehicle’s efficiency has a bigger absolute impact on fuel use.
How to measure your MPG
Fill the tank completely, reset your trip odometer (or note the mileage), then drive normally until you need fuel again. Fill the tank completely a second time and note how many gallons it took. Divide the trip miles by the gallons to get your real-world MPG. Repeat over 2-3 tanks for a more reliable average, since driving conditions (highway vs. city, weather, load) affect fuel economy significantly.
EPA ratings vs. real-world MPG
EPA fuel economy estimates use standardized test cycles on a dynamometer. Real-world driving typically yields 10-20% lower MPG than the EPA combined rating because of factors like aggressive acceleration, highway speeds above 60 mph, cold weather, air conditioning, and carrying extra weight. The EPA city rating is usually the more realistic benchmark for mixed driving.
Worked example
For a 300-mile trip using 10 gallons at $3.50 per gallon: MPG = 300 / 10 = 30. Gallons per 100 miles = (10 / 300) x 100 = 3.33. Total cost = 10 x $3.50 = $35. Cost per mile = $35 / 300 = $0.117, or about 12 cents per mile.