Gas Mileage Calculator
Calculate your actual MPG from odometer readings or miles driven and gallons used. Track multiple fill-ups, convert units, and compare against your EPA rating.
3
UNIT MODES
MPG
L/100KM/KM/L
Log
FILL-UP LOG
EPA
RATING COMPARE
Gas Mileage Calculator
Calculate your real-world MPG
27.0
Your MPG
8.7
L/100km
km/L: 11.46
UK MPG: 32.4
Cost per mile: $0.130
25% below EPA rating
FUEL EFFICIENCY CONVERTER
Convert MPG ↔ L/100km ↔ km/L
Enter any value — the other two convert instantly.
Also see: UK MPG conversion and cost/mile at $3.50/gal in the calculator above.
MPG REFERENCE
What Is Good Gas Mileage?
EPA combined MPG benchmarks by vehicle class. Higher is better for gas vehicles.
| Vehicle Class | Typical MPG | L/100km | Rating | Fuel Cost/Mile* |
|---|---|---|---|---|
| Hybrid sedan (2024) | 40-58 MPG | 4.1-5.9 | Excellent | 6-9¢/mile |
| Compact car | 30-38 MPG | 6.2-7.8 | Very Good | 9-12¢/mile |
| Mid-size sedan | 26-32 MPG | 7.4-9.0 | Good | 11-13¢/mile |
| Small SUV / crossover | 26-34 MPG | 6.9-9.0 | Good | 10-13¢/mile |
| Mid-size SUV | 20-26 MPG | 9.0-11.8 | Average | 13-18¢/mile |
| Full-size pickup truck | 16-22 MPG | 10.7-14.7 | Low | 16-22¢/mile |
| Performance / sports car | 13-25 MPG | 9.4-15.7 | Low-Average | 14-27¢/mile |
| Electric (MPGe) | 100-138 MPGe | — | Best | 3-5¢/mile* |
*Based on $3.50/gallon (EV figure is per-mile electricity-equivalent cost)
FUEL ECONOMY TIPS
How to Improve Your Gas Mileage
Slow Down on Highways
Aerodynamic drag increases with the square of speed. Each 5 mph over 60 mph costs roughly 7-14% more fuel.
Smooth Acceleration
Aggressive acceleration and hard braking wastes 15-30% more fuel in city driving than smooth, anticipatory driving.
Maintain Tire Pressure
Under-inflated tires increase rolling resistance. Every 1 PSI under can cost up to 0.3% of your MPG.
Regular Maintenance
A dirty air filter reduces airflow to the engine. Worn spark plugs cause incomplete, inefficient combustion.
Reduce Weight & Drag
Remove roof racks and cargo carriers when not in use. Every 100 extra lbs costs roughly 1-2% of your MPG.
Manage A/C and Cold Starts
A/C use reduces MPG by 5-25% depending on conditions. Cold starts burn more fuel until the engine warms up.
💡 A Sudden MPG Drop Is a Warning Sign
If your calculated MPG drops more than 10-15% from your usual baseline, it can indicate a maintenance issue — a dirty air filter, low tire pressure, a clogged fuel injector, or a failing O2 sensor. Tracking your MPG over time with a simple fill-up log turns your gas pump into a free diagnostic tool.
🛣️ City vs Highway MPG
Conventional gas cars get 25-35% better MPG on the highway than in city driving, which involves frequent stops, idling, and acceleration from rest. The EPA's combined rating (roughly 55% city / 45% highway) tries to reflect typical use — mostly-highway commuters often beat it, while city commuters usually fall short. Hybrids reverse this pattern: regenerative braking makes them relatively better in stop-and-go traffic.
🌍 US MPG vs UK MPG vs L/100km
The US uses US gallons (3.785L) while the UK uses Imperial gallons (4.546L) — a UK MPG rating reads about 20% higher than the same car's US MPG for identical fuel use. Always check which standard a figure uses before comparing. Europe and most of the world uses L/100km instead, where lower is better: a 30 US MPG car is about 7.84 L/100km, a 50 MPG hybrid about 4.71 L/100km. Use the converter above to switch between any of these units.
How to Calculate Gas Mileage — Step by Step
Calculating your actual gas mileage takes nothing more than a pen, a odometer reading, and your gas pump receipt. Doing this consistently reveals your real-world MPG and can flag mechanical problems early.
Method 1: From Odometer Readings
Step 1: Fill tank to full, note odometer reading (X)
Step 2: Drive as you normally would
Step 3: Fill tank again, note new odometer (B), gallons added to refill (G)
MPG = (B − X) ÷ G
Example: 48,230 → 48,540 miles, 11.5 gallons: (48,540 − 48,230) ÷ 11.5 = 27.0 MPG
Tip: repeat 3-4 times for a reliable average — pump nozzle shutoff and tank angle vary each fill.Fuel Efficiency Unit Conversions
L/100km = 235.214 ÷ MPG(US)
MPG(UK) = MPG(US) × 1.20095
Quick reference: 20 MPG = 11.76 L/100km · 30 MPG = 7.84 L/100km · 40 MPG = 5.88 L/100km · 50 MPG = 4.71 L/100kmCost Per Mile Formula
Cost per mile = Price ($/gallon) ÷ MPG
Examples at $3.50/gallon: 20 MPG = $0.175/mile · 25 MPG = $0.14/mile · 30 MPG = $0.117/mile
Annual cost: 12,500 mi/yr at 25 MPG = 500 gal/yr × $3.50 = $1,750/year— FAQ