Fuel Efficiency Calculator

Measure real fuel efficiency vs. rated MPG

miles
gal
mpg
$/gal

How to Use the Fuel Efficiency Calculator

Fill up your tank completely, drive as usual, then fill up again. Enter the miles you drove and the gallons used in the second fill-up to get your true MPG. Compare it to the EPA rating to see how your driving habits affect efficiency.

Real-world fuel efficiency depends on AC use, city vs. highway driving, cargo weight, tire pressure, and driving style. Tracking it regularly helps you spot trends and identify maintenance issues early.

Frequently Asked Questions

How do I get the most accurate reading?

Always fill to the same pump shutoff point at the same station if possible. Partial fills introduce measurement error. Multiple consecutive fill-ups give a more reliable average.

My MPG suddenly dropped — what should I check?

Check tire pressure, air filter, spark plugs, and brakes for drag. A drop of more than 10% from your baseline usually signals a maintenance issue worth investigating.

What is cost per 100 miles?

It shows how much fuel costs you to drive 100 miles. Calculated as: (Gas Price ÷ MPG) × 100. Lower MPG means higher cost per mile, making it a useful comparison metric.