Last updated October 13, 2026 · Report an error
Your vehicle's real-world fuel economy can differ noticeably from its window-sticker rating, depending on driving conditions and habits.
This calculator finds your actual miles per gallon (MPG) from a real distance and fuel amount, and estimates your cost per mile.
How it works
Enter the distance traveled and gallons of fuel used (typically measured between two fill-ups). The calculator divides distance by gallons used to find MPG, and — if you provide a fuel price — also calculates your cost per mile.
- Enter distance traveled (miles).
- Enter fuel used (gallons).
- Enter price per gallon ($, optional).
- Click Calculate to see your results.
Examples
300 miles on 10 gallons
Traveling 300 miles on 10 gallons of gas gives a fuel economy of exactly 30 MPG, costing about $0.117/mile at $3.50/gallon.
Who should use it
- Checking your vehicle's real-world fuel economy against its EPA rating.
- Tracking fuel economy changes over time (e.g., after maintenance or a driving habit change).
Industry applications
- Automotive maintenance and fleet management
- Personal budgeting and vehicle ownership costs
Advantages
- Uses your actual real-world driving data rather than an EPA estimate.
- Optionally shows cost per mile alongside fuel economy.
Limitations
- Accuracy depends on how precisely you measure distance and fuel used between fill-ups.
Common mistakes to avoid
- Measuring gallons used from a partial fill-up rather than a full tank-to-tank measurement, which introduces error.
- Forgetting to reset the trip odometer before starting the measurement period.
Best practices
- Repeat the tank-to-tank measurement across a few fill-ups and average the results for a more reliable real-world MPG figure.
Tips
- Once you know your real-world MPG here, plug it into the Fuel Cost Calculator to estimate the cost of any future trip.
Frequently asked questions
Yes, with no signup and no limit on how many trips you check.
This calculator finds your actual MPG from a real distance and fuel amount; the Fuel Cost Calculator goes the other direction — using an already-known MPG figure to estimate the cost of a planned trip.
Fill your tank completely, reset your trip odometer, drive normally, then fill up completely again — the gallons needed to refill and the distance on the trip odometer give you an accurate real-world measurement.
EPA window-sticker ratings are measured under standardized test conditions — real-world driving (city traffic, highway speed, weather, cargo load) commonly produces different actual fuel economy.