MPG Calculator
Calculate your actual fuel efficiency from your last fill-up. Enter the miles driven and gallons used to find your MPG, cost per mile, and projected annual fuel costs. Compare your vehicle to common benchmarks.
Miles per gallon (MPG) is the standard U.S. measure of vehicle fuel efficiency: how many miles a vehicle travels per gallon of gasoline. Higher is better. A typical compact sedan returns 30–40 MPG in mixed driving; full-size SUVs and pickups return 17–25; hybrids 45–55; and EVs are measured in MPGe (a gasoline equivalent) usually around 100+.
This calculator computes your actual real-world MPG from a single tank's data — miles driven divided by gallons to refill. It also calculates cost per mile and projects annual fuel cost based on a typical 13,500-mile-per-year driving pattern. Real MPG differs from EPA sticker ratings; tracking your own number over a few tanks gives a much more accurate picture of what the vehicle actually costs to operate.
Use this any time you switch vehicles, suspect a maintenance issue (sudden MPG drops can indicate problems with O2 sensors, air filters, or tires), or want to budget fuel costs for a long trip.
Inputs
Results
Your MPG
29.2 mpg
Cost per Mile
$0.12
Annual Fuel Cost
$1,440
Based on 12,000 mi/yr
Monthly Fuel Cost
$120
Annual Fuel Cost Comparison
MPG Comparison (12,000 mi/yr)
| Vehicle Type | MPG | Annual Fuel Cost |
|---|---|---|
| Your Vehicle | 29.167 | $1,440.00 |
| Compact Car (35 mpg) | 35 | $1,200.00 |
| Sedan (30 mpg) | 30 | $1,400.00 |
| SUV (25 mpg) | 25 | $1,680.00 |
| Truck (20 mpg) | 20 | $2,100.00 |
Formula
How to use this calculator
- Fill your tank completely and reset the trip odometer.
- Drive normally for at least 200 miles (longer is more accurate — single short tanks can swing 5–10% from your true average).
- Fill up again at the same pump style (top off to the first auto-shutoff).
- Note miles driven (from trip odometer) and gallons added (from the pump receipt).
- Enter both into the calculator. The result is your tank-averaged MPG.
- Repeat for 3+ tanks and average for the most reliable real-world MPG.
- Enter current gas price for cost-per-mile and annual-cost projections.
Worked examples
Compact sedan
350 miles, 12 gallons, gas at $3.50/gal. MPG: 29.2 Cost/mile: $0.12 Annual cost (13,500 mi): ≈ $1,617 This is roughly the EPA average for a non-hybrid car. Improvements: smoother acceleration, proper tire pressure, removing roof racks/cargo when not needed.
EV cost-per-mile comparison
An EV at 4 miles per kWh, electricity at $0.15/kWh: Cost per mile: $0.15 / 4 = $0.038/mile The same 13,500 mi/yr costs about $506 — roughly $1,100 less than the 29 MPG gas car.
When to use this calculator
Use this every few tanks to track real MPG over time, after vehicle maintenance to confirm efficiency restored, when shopping cars (compare your driving pattern's real cost), and when planning long trips.
A few practical notes: - Cold-weather MPG drops 10–25% (winter gasoline blends + idle warm-up + heater) - City driving is typically 30–40% worse than highway for non-hybrids; hybrids close the gap - EPA combined ratings assume 55% city / 45% highway driving; adjust expectations for your pattern - Sudden MPG drop of 15%+ usually indicates a problem (O2 sensor, dirty air filter, low tire pressure, brake drag)
Common mistakes to avoid
- Calculating MPG from a single short tank. Trip variability dominates; use 3+ tanks averaged.
- Filling up differently each time (varying auto-shutoff sensitivity). Use the same pump style.
- Confusing trip odometer with main odometer reading. The trip resets per fill-up; the main accumulates.
- Comparing to EPA sticker without context. Real-world MPG is often 10–20% lower for the average driver.
- Ignoring tire pressure. Under-inflated tires can cost 2–4 MPG.
- Not accounting for ethanol content. E85 has ~28% less energy than gasoline; MPG drops correspondingly.
Frequently Asked Questions
Sources & further reading
- Fuel economy guide — U.S. Department of Energy & EPA
- EPA fuel economy testing methodology — U.S. Environmental Protection Agency